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Imaging of Musculoskeletal Liposarcoma with Radiologic-Pathologic Correlation¹

¹ From the Departments of Radiologic Pathology (M.D.M., L.K.A.) and Soft Tissue Pathology (J.F.S.), Armed Forces Institute of Pathology, 6825 16th St NW, Bldg 54, Rm M-133A, Washington, DC 20306; Department of Radiology, University of Maryland School of Medicine, Baltimore (M.D.M.); and Department of Radiology, Walter Reed Army Medical Center, Washington, DC (M.D.M.). Received April 29, 2005; revision requested May 26 and received June 20; accepted June 21. All authors have no financial relationships to disclose.

View larger version (69K): [in a new window]   Figure 1a.  Well-differentiated liposarcoma in a 68-year-old man who presented with a slowly enlarging, painless thigh mass. (a) Anteroposterior radiograph shows a mildly heterogeneous mass with radiolucent fat (*). (b) CT scan reveals a heterogeneous, posterior compartment, intramuscular mass composed predominantly of fat (*), with thick septa (arrows) and a nodular focus (arrowhead) of soft-tissue attenuation. (c) Axial T1-weighted (repetition time msec/echo time msec = 400/14) MR image shows the predominant signal intensity of fat (*) with thick septa (arrows) and a nodular nonlipomatous focus of intermediate signal intensity (arrowhead). (d, e) Axial (d) and coronal (e) contrast material–enhanced, fat-suppressed, T1-weighted MR images (683/14) demonstrate enhancement of the septa (arrows) and focal nonlipomatous nodular region (arrowhead) with suppression of the predominant adipose component (*). (f) Axial T2-weighted (5000/96) MR image shows high signal intensity in the septa (arrows) and nodular nonlipomatous focus (arrowhead), with other areas being isointense relative to subcutaneous fat. (g) Photograph of the axially sectioned gross specimen reveals the predominant yellow to tan adipose mass (*) with thick septa (arrows) and a nodular hemorrhagic component (arrowhead) that correspond to imaging findings. The nodular focus requires biopsy to exclude a region of dedifferentiation, which was not seen histologically in this case.

 

View larger version (60K): [in a new window]   Figure 1b.  Well-differentiated liposarcoma in a 68-year-old man who presented with a slowly enlarging, painless thigh mass. (a) Anteroposterior radiograph shows a mildly heterogeneous mass with radiolucent fat (*). (b) CT scan reveals a heterogeneous, posterior compartment, intramuscular mass composed predominantly of fat (*), with thick septa (arrows) and a nodular focus (arrowhead) of soft-tissue attenuation. (c) Axial T1-weighted (repetition time msec/echo time msec = 400/14) MR image shows the predominant signal intensity of fat (*) with thick septa (arrows) and a nodular nonlipomatous focus of intermediate signal intensity (arrowhead). (d, e) Axial (d) and coronal (e) contrast material–enhanced, fat-suppressed, T1-weighted MR images (683/14) demonstrate enhancement of the septa (arrows) and focal nonlipomatous nodular region (arrowhead) with suppression of the predominant adipose component (*). (f) Axial T2-weighted (5000/96) MR image shows high signal intensity in the septa (arrows) and nodular nonlipomatous focus (arrowhead), with other areas being isointense relative to subcutaneous fat. (g) Photograph of the axially sectioned gross specimen reveals the predominant yellow to tan adipose mass (*) with thick septa (arrows) and a nodular hemorrhagic component (arrowhead) that correspond to imaging findings. The nodular focus requires biopsy to exclude a region of dedifferentiation, which was not seen histologically in this case.

 

View larger version (87K): [in a new window]   Figure 1c.  Well-differentiated liposarcoma in a 68-year-old man who presented with a slowly enlarging, painless thigh mass. (a) Anteroposterior radiograph shows a mildly heterogeneous mass with radiolucent fat (*). (b) CT scan reveals a heterogeneous, posterior compartment, intramuscular mass composed predominantly of fat (*), with thick septa (arrows) and a nodular focus (arrowhead) of soft-tissue attenuation. (c) Axial T1-weighted (repetition time msec/echo time msec = 400/14) MR image shows the predominant signal intensity of fat (*) with thick septa (arrows) and a nodular nonlipomatous focus of intermediate signal intensity (arrowhead). (d, e) Axial (d) and coronal (e) contrast material–enhanced, fat-suppressed, T1-weighted MR images (683/14) demonstrate enhancement of the septa (arrows) and focal nonlipomatous nodular region (arrowhead) with suppression of the predominant adipose component (*). (f) Axial T2-weighted (5000/96) MR image shows high signal intensity in the septa (arrows) and nodular nonlipomatous focus (arrowhead), with other areas being isointense relative to subcutaneous fat. (g) Photograph of the axially sectioned gross specimen reveals the predominant yellow to tan adipose mass (*) with thick septa (arrows) and a nodular hemorrhagic component (arrowhead) that correspond to imaging findings. The nodular focus requires biopsy to exclude a region of dedifferentiation, which was not seen histologically in this case.

 

View larger version (90K): [in a new window]   Figure 1d.  Well-differentiated liposarcoma in a 68-year-old man who presented with a slowly enlarging, painless thigh mass. (a) Anteroposterior radiograph shows a mildly heterogeneous mass with radiolucent fat (*). (b) CT scan reveals a heterogeneous, posterior compartment, intramuscular mass composed predominantly of fat (*), with thick septa (arrows) and a nodular focus (arrowhead) of soft-tissue attenuation. (c) Axial T1-weighted (repetition time msec/echo time msec = 400/14) MR image shows the predominant signal intensity of fat (*) with thick septa (arrows) and a nodular nonlipomatous focus of intermediate signal intensity (arrowhead). (d, e) Axial (d) and coronal (e) contrast material–enhanced, fat-suppressed, T1-weighted MR images (683/14) demonstrate enhancement of the septa (arrows) and focal nonlipomatous nodular region (arrowhead) with suppression of the predominant adipose component (*). (f) Axial T2-weighted (5000/96) MR image shows high signal intensity in the septa (arrows) and nodular nonlipomatous focus (arrowhead), with other areas being isointense relative to subcutaneous fat. (g) Photograph of the axially sectioned gross specimen reveals the predominant yellow to tan adipose mass (*) with thick septa (arrows) and a nodular hemorrhagic component (arrowhead) that correspond to imaging findings. The nodular focus requires biopsy to exclude a region of dedifferentiation, which was not seen histologically in this case.

 

View larger version (98K): [in a new window]   Figure 1e.  Well-differentiated liposarcoma in a 68-year-old man who presented with a slowly enlarging, painless thigh mass. (a) Anteroposterior radiograph shows a mildly heterogeneous mass with radiolucent fat (*). (b) CT scan reveals a heterogeneous, posterior compartment, intramuscular mass composed predominantly of fat (*), with thick septa (arrows) and a nodular focus (arrowhead) of soft-tissue attenuation. (c) Axial T1-weighted (repetition time msec/echo time msec = 400/14) MR image shows the predominant signal intensity of fat (*) with thick septa (arrows) and a nodular nonlipomatous focus of intermediate signal intensity (arrowhead). (d, e) Axial (d) and coronal (e) contrast material–enhanced, fat-suppressed, T1-weighted MR images (683/14) demonstrate enhancement of the septa (arrows) and focal nonlipomatous nodular region (arrowhead) with suppression of the predominant adipose component (*). (f) Axial T2-weighted (5000/96) MR image shows high signal intensity in the septa (arrows) and nodular nonlipomatous focus (arrowhead), with other areas being isointense relative to subcutaneous fat. (g) Photograph of the axially sectioned gross specimen reveals the predominant yellow to tan adipose mass (*) with thick septa (arrows) and a nodular hemorrhagic component (arrowhead) that correspond to imaging findings. The nodular focus requires biopsy to exclude a region of dedifferentiation, which was not seen histologically in this case.

 

View larger version (91K): [in a new window]   Figure 1f.  Well-differentiated liposarcoma in a 68-year-old man who presented with a slowly enlarging, painless thigh mass. (a) Anteroposterior radiograph shows a mildly heterogeneous mass with radiolucent fat (*). (b) CT scan reveals a heterogeneous, posterior compartment, intramuscular mass composed predominantly of fat (*), with thick septa (arrows) and a nodular focus (arrowhead) of soft-tissue attenuation. (c) Axial T1-weighted (repetition time msec/echo time msec = 400/14) MR image shows the predominant signal intensity of fat (*) with thick septa (arrows) and a nodular nonlipomatous focus of intermediate signal intensity (arrowhead). (d, e) Axial (d) and coronal (e) contrast material–enhanced, fat-suppressed, T1-weighted MR images (683/14) demonstrate enhancement of the septa (arrows) and focal nonlipomatous nodular region (arrowhead) with suppression of the predominant adipose component (*). (f) Axial T2-weighted (5000/96) MR image shows high signal intensity in the septa (arrows) and nodular nonlipomatous focus (arrowhead), with other areas being isointense relative to subcutaneous fat. (g) Photograph of the axially sectioned gross specimen reveals the predominant yellow to tan adipose mass (*) with thick septa (arrows) and a nodular hemorrhagic component (arrowhead) that correspond to imaging findings. The nodular focus requires biopsy to exclude a region of dedifferentiation, which was not seen histologically in this case.

 

View larger version (126K): [in a new window]   Figure 1g.  Well-differentiated liposarcoma in a 68-year-old man who presented with a slowly enlarging, painless thigh mass. (a) Anteroposterior radiograph shows a mildly heterogeneous mass with radiolucent fat (*). (b) CT scan reveals a heterogeneous, posterior compartment, intramuscular mass composed predominantly of fat (*), with thick septa (arrows) and a nodular focus (arrowhead) of soft-tissue attenuation. (c) Axial T1-weighted (repetition time msec/echo time msec = 400/14) MR image shows the predominant signal intensity of fat (*) with thick septa (arrows) and a nodular nonlipomatous focus of intermediate signal intensity (arrowhead). (d, e) Axial (d) and coronal (e) contrast material–enhanced, fat-suppressed, T1-weighted MR images (683/14) demonstrate enhancement of the septa (arrows) and focal nonlipomatous nodular region (arrowhead) with suppression of the predominant adipose component (*). (f) Axial T2-weighted (5000/96) MR image shows high signal intensity in the septa (arrows) and nodular nonlipomatous focus (arrowhead), with other areas being isointense relative to subcutaneous fat. (g) Photograph of the axially sectioned gross specimen reveals the predominant yellow to tan adipose mass (*) with thick septa (arrows) and a nodular hemorrhagic component (arrowhead) that correspond to imaging findings. The nodular focus requires biopsy to exclude a region of dedifferentiation, which was not seen histologically in this case.

 

View larger version (128K): [in a new window]   Figure 2a.  Well-differentiated intermuscular liposarcoma of the thigh in a 72-year-old woman with a history of a painless, slow-growing mass. Radiographs (not shown) were unremarkable. (a) CT scan shows an intermuscular mass between the superficial fascia (arrow) and vastus lateralis muscle (VL) that is predominantly composed of fat attenuation (*) with prominent thick and nodular septa (arrowheads). (b–d) Axial T1-weighted (500/13) (b), contrast-enhanced T1-weighted fat-suppressed (523/13) (c), and T2-weighted (2300/15) (d) MR images also reveal a lipomatous mass (*) with prominent septa (arrows) and enhancement. (e) Photograph of the excised specimen demonstrates the predominantly yellow lipomatous mass (*) with thick septa (arrows). (f) Photomicrograph (original magnification, x 175; hematoxylin-eosin stain) shows the adipose tissue (*) and thick septa (S).

 

View larger version (141K): [in a new window]   Figure 2b.  Well-differentiated intermuscular liposarcoma of the thigh in a 72-year-old woman with a history of a painless, slow-growing mass. Radiographs (not shown) were unremarkable. (a) CT scan shows an intermuscular mass between the superficial fascia (arrow) and vastus lateralis muscle (VL) that is predominantly composed of fat attenuation (*) with prominent thick and nodular septa (arrowheads). (b–d) Axial T1-weighted (500/13) (b), contrast-enhanced T1-weighted fat-suppressed (523/13) (c), and T2-weighted (2300/15) (d) MR images also reveal a lipomatous mass (*) with prominent septa (arrows) and enhancement. (e) Photograph of the excised specimen demonstrates the predominantly yellow lipomatous mass (*) with thick septa (arrows). (f) Photomicrograph (original magnification, x 175; hematoxylin-eosin stain) shows the adipose tissue (*) and thick septa (S).

 

View larger version (145K): [in a new window]   Figure 2c.  Well-differentiated intermuscular liposarcoma of the thigh in a 72-year-old woman with a history of a painless, slow-growing mass. Radiographs (not shown) were unremarkable. (a) CT scan shows an intermuscular mass between the superficial fascia (arrow) and vastus lateralis muscle (VL) that is predominantly composed of fat attenuation (*) with prominent thick and nodular septa (arrowheads). (b–d) Axial T1-weighted (500/13) (b), contrast-enhanced T1-weighted fat-suppressed (523/13) (c), and T2-weighted (2300/15) (d) MR images also reveal a lipomatous mass (*) with prominent septa (arrows) and enhancement. (e) Photograph of the excised specimen demonstrates the predominantly yellow lipomatous mass (*) with thick septa (arrows). (f) Photomicrograph (original magnification, x 175; hematoxylin-eosin stain) shows the adipose tissue (*) and thick septa (S).

 

View larger version (142K): [in a new window]   Figure 2d.  Well-differentiated intermuscular liposarcoma of the thigh in a 72-year-old woman with a history of a painless, slow-growing mass. Radiographs (not shown) were unremarkable. (a) CT scan shows an intermuscular mass between the superficial fascia (arrow) and vastus lateralis muscle (VL) that is predominantly composed of fat attenuation (*) with prominent thick and nodular septa (arrowheads). (b–d) Axial T1-weighted (500/13) (b), contrast-enhanced T1-weighted fat-suppressed (523/13) (c), and T2-weighted (2300/15) (d) MR images also reveal a lipomatous mass (*) with prominent septa (arrows) and enhancement. (e) Photograph of the excised specimen demonstrates the predominantly yellow lipomatous mass (*) with thick septa (arrows). (f) Photomicrograph (original magnification, x 175; hematoxylin-eosin stain) shows the adipose tissue (*) and thick septa (S).

 

View larger version (87K): [in a new window]   Figure 2e.  Well-differentiated intermuscular liposarcoma of the thigh in a 72-year-old woman with a history of a painless, slow-growing mass. Radiographs (not shown) were unremarkable. (a) CT scan shows an intermuscular mass between the superficial fascia (arrow) and vastus lateralis muscle (VL) that is predominantly composed of fat attenuation (*) with prominent thick and nodular septa (arrowheads). (b–d) Axial T1-weighted (500/13) (b), contrast-enhanced T1-weighted fat-suppressed (523/13) (c), and T2-weighted (2300/15) (d) MR images also reveal a lipomatous mass (*) with prominent septa (arrows) and enhancement. (e) Photograph of the excised specimen demonstrates the predominantly yellow lipomatous mass (*) with thick septa (arrows). (f) Photomicrograph (original magnification, x 175; hematoxylin-eosin stain) shows the adipose tissue (*) and thick septa (S).

 

View larger version (166K): [in a new window]   Figure 2f.  Well-differentiated intermuscular liposarcoma of the thigh in a 72-year-old woman with a history of a painless, slow-growing mass. Radiographs (not shown) were unremarkable. (a) CT scan shows an intermuscular mass between the superficial fascia (arrow) and vastus lateralis muscle (VL) that is predominantly composed of fat attenuation (*) with prominent thick and nodular septa (arrowheads). (b–d) Axial T1-weighted (500/13) (b), contrast-enhanced T1-weighted fat-suppressed (523/13) (c), and T2-weighted (2300/15) (d) MR images also reveal a lipomatous mass (*) with prominent septa (arrows) and enhancement. (e) Photograph of the excised specimen demonstrates the predominantly yellow lipomatous mass (*) with thick septa (arrows). (f) Photomicrograph (original magnification, x 175; hematoxylin-eosin stain) shows the adipose tissue (*) and thick septa (S).

 

View larger version (79K): [in a new window]   Figure 3a.  Well-differentiated liposarcoma of the thigh in a 65-year-old woman with a 3-year history of a slowly growing, painless mass. (a) Lateral radiograph of the thigh shows a large mass with prominent radiolucent fat (*). (b) CT scan reveals the low-attenuation fat (*) with numerous thick (>2 mm) septa (arrows) and encasement of the neurovascular bundle (arrowhead). (c, d) Axial (700/14) (c) and sagittal (650/14) (d) T1-weighted MR images demonstrate a high-signal-intensity adipose lesion that involves both intramuscular and intermuscular portions of the posterior thigh compartment (*) and that contains thick septa (solid arrows) and several areas of mild nodularity (arrowheads). The axial image also reveals encasement of the neurovascular bundle (open arrow). (e) Sagittal T2-weighted (2100/90) MR image shows that the tissue is isointense relative to subcutaneous fat (*); the thick septa reveal both high and low signal intensity (arrows). (f) Intraoperative photograph demonstrates the large lipomatous mass (L) and mobilization of the neurovascular bundle (N). (g) Photograph of the sectioned gross specimen shows the yellow lipomatous tissue (L) and multiple septa (arrows).

 

View larger version (161K): [in a new window]   Figure 3b.  Well-differentiated liposarcoma of the thigh in a 65-year-old woman with a 3-year history of a slowly growing, painless mass. (a) Lateral radiograph of the thigh shows a large mass with prominent radiolucent fat (*). (b) CT scan reveals the low-attenuation fat (*) with numerous thick (>2 mm) septa (arrows) and encasement of the neurovascular bundle (arrowhead). (c, d) Axial (700/14) (c) and sagittal (650/14) (d) T1-weighted MR images demonstrate a high-signal-intensity adipose lesion that involves both intramuscular and intermuscular portions of the posterior thigh compartment (*) and that contains thick septa (solid arrows) and several areas of mild nodularity (arrowheads). The axial image also reveals encasement of the neurovascular bundle (open arrow). (e) Sagittal T2-weighted (2100/90) MR image shows that the tissue is isointense relative to subcutaneous fat (*); the thick septa reveal both high and low signal intensity (arrows). (f) Intraoperative photograph demonstrates the large lipomatous mass (L) and mobilization of the neurovascular bundle (N). (g) Photograph of the sectioned gross specimen shows the yellow lipomatous tissue (L) and multiple septa (arrows).

 

View larger version (165K): [in a new window]   Figure 3c.  Well-differentiated liposarcoma of the thigh in a 65-year-old woman with a 3-year history of a slowly growing, painless mass. (a) Lateral radiograph of the thigh shows a large mass with prominent radiolucent fat (*). (b) CT scan reveals the low-attenuation fat (*) with numerous thick (>2 mm) septa (arrows) and encasement of the neurovascular bundle (arrowhead). (c, d) Axial (700/14) (c) and sagittal (650/14) (d) T1-weighted MR images demonstrate a high-signal-intensity adipose lesion that involves both intramuscular and intermuscular portions of the posterior thigh compartment (*) and that contains thick septa (solid arrows) and several areas of mild nodularity (arrowheads). The axial image also reveals encasement of the neurovascular bundle (open arrow). (e) Sagittal T2-weighted (2100/90) MR image shows that the tissue is isointense relative to subcutaneous fat (*); the thick septa reveal both high and low signal intensity (arrows). (f) Intraoperative photograph demonstrates the large lipomatous mass (L) and mobilization of the neurovascular bundle (N). (g) Photograph of the sectioned gross specimen shows the yellow lipomatous tissue (L) and multiple septa (arrows).

 

View larger version (106K): [in a new window]   Figure 3d.  Well-differentiated liposarcoma of the thigh in a 65-year-old woman with a 3-year history of a slowly growing, painless mass. (a) Lateral radiograph of the thigh shows a large mass with prominent radiolucent fat (*). (b) CT scan reveals the low-attenuation fat (*) with numerous thick (>2 mm) septa (arrows) and encasement of the neurovascular bundle (arrowhead). (c, d) Axial (700/14) (c) and sagittal (650/14) (d) T1-weighted MR images demonstrate a high-signal-intensity adipose lesion that involves both intramuscular and intermuscular portions of the posterior thigh compartment (*) and that contains thick septa (solid arrows) and several areas of mild nodularity (arrowheads). The axial image also reveals encasement of the neurovascular bundle (open arrow). (e) Sagittal T2-weighted (2100/90) MR image shows that the tissue is isointense relative to subcutaneous fat (*); the thick septa reveal both high and low signal intensity (arrows). (f) Intraoperative photograph demonstrates the large lipomatous mass (L) and mobilization of the neurovascular bundle (N). (g) Photograph of the sectioned gross specimen shows the yellow lipomatous tissue (L) and multiple septa (arrows).

 

View larger version (99K): [in a new window]   Figure 3e.  Well-differentiated liposarcoma of the thigh in a 65-year-old woman with a 3-year history of a slowly growing, painless mass. (a) Lateral radiograph of the thigh shows a large mass with prominent radiolucent fat (*). (b) CT scan reveals the low-attenuation fat (*) with numerous thick (>2 mm) septa (arrows) and encasement of the neurovascular bundle (arrowhead). (c, d) Axial (700/14) (c) and sagittal (650/14) (d) T1-weighted MR images demonstrate a high-signal-intensity adipose lesion that involves both intramuscular and intermuscular portions of the posterior thigh compartment (*) and that contains thick septa (solid arrows) and several areas of mild nodularity (arrowheads). The axial image also reveals encasement of the neurovascular bundle (open arrow). (e) Sagittal T2-weighted (2100/90) MR image shows that the tissue is isointense relative to subcutaneous fat (*); the thick septa reveal both high and low signal intensity (arrows). (f) Intraoperative photograph demonstrates the large lipomatous mass (L) and mobilization of the neurovascular bundle (N). (g) Photograph of the sectioned gross specimen shows the yellow lipomatous tissue (L) and multiple septa (arrows).

 

View larger version (113K): [in a new window]   Figure 3f.  Well-differentiated liposarcoma of the thigh in a 65-year-old woman with a 3-year history of a slowly growing, painless mass. (a) Lateral radiograph of the thigh shows a large mass with prominent radiolucent fat (*). (b) CT scan reveals the low-attenuation fat (*) with numerous thick (>2 mm) septa (arrows) and encasement of the neurovascular bundle (arrowhead). (c, d) Axial (700/14) (c) and sagittal (650/14) (d) T1-weighted MR images demonstrate a high-signal-intensity adipose lesion that involves both intramuscular and intermuscular portions of the posterior thigh compartment (*) and that contains thick septa (solid arrows) and several areas of mild nodularity (arrowheads). The axial image also reveals encasement of the neurovascular bundle (open arrow). (e) Sagittal T2-weighted (2100/90) MR image shows that the tissue is isointense relative to subcutaneous fat (*); the thick septa reveal both high and low signal intensity (arrows). (f) Intraoperative photograph demonstrates the large lipomatous mass (L) and mobilization of the neurovascular bundle (N). (g) Photograph of the sectioned gross specimen shows the yellow lipomatous tissue (L) and multiple septa (arrows).

 

View larger version (100K): [in a new window]   Figure 3g.  Well-differentiated liposarcoma of the thigh in a 65-year-old woman with a 3-year history of a slowly growing, painless mass. (a) Lateral radiograph of the thigh shows a large mass with prominent radiolucent fat (*). (b) CT scan reveals the low-attenuation fat (*) with numerous thick (>2 mm) septa (arrows) and encasement of the neurovascular bundle (arrowhead). (c, d) Axial (700/14) (c) and sagittal (650/14) (d) T1-weighted MR images demonstrate a high-signal-intensity adipose lesion that involves both intramuscular and intermuscular portions of the posterior thigh compartment (*) and that contains thick septa (solid arrows) and several areas of mild nodularity (arrowheads). The axial image also reveals encasement of the neurovascular bundle (open arrow). (e) Sagittal T2-weighted (2100/90) MR image shows that the tissue is isointense relative to subcutaneous fat (*); the thick septa reveal both high and low signal intensity (arrows). (f) Intraoperative photograph demonstrates the large lipomatous mass (L) and mobilization of the neurovascular bundle (N). (g) Photograph of the sectioned gross specimen shows the yellow lipomatous tissue (L) and multiple septa (arrows).

 

View larger version (109K): [in a new window]   Figure 4a.  Subcutaneous atypical lipomatous tumor/well-differentiated liposarcoma in a 55-year-old man who presented with an enlarging, mildly painful mass. (a, b) Coronal T1-weighted (500/20) (a) and axial T2-weighted (2500/90) (b) MR images show a largely lipomatous subcutaneous mass (*) with prominent thick and nodular septa (arrows). (c) Photomicrograph (original magnification, x175; hematoxylin-eosin stain) reveals typical features of a lipoma-like atypical lipomatous tumor/well-differentiated liposarcoma with largely mature adipocytes (A), only mild atypia (arrows), and thick septa (S).

 

View larger version (156K): [in a new window]   Figure 4b.  Subcutaneous atypical lipomatous tumor/well-differentiated liposarcoma in a 55-year-old man who presented with an enlarging, mildly painful mass. (a, b) Coronal T1-weighted (500/20) (a) and axial T2-weighted (2500/90) (b) MR images show a largely lipomatous subcutaneous mass (*) with prominent thick and nodular septa (arrows). (c) Photomicrograph (original magnification, x175; hematoxylin-eosin stain) reveals typical features of a lipoma-like atypical lipomatous tumor/well-differentiated liposarcoma with largely mature adipocytes (A), only mild atypia (arrows), and thick septa (S).

 

View larger version (138K): [in a new window]   Figure 4c.  Subcutaneous atypical lipomatous tumor/well-differentiated liposarcoma in a 55-year-old man who presented with an enlarging, mildly painful mass. (a, b) Coronal T1-weighted (500/20) (a) and axial T2-weighted (2500/90) (b) MR images show a largely lipomatous subcutaneous mass (*) with prominent thick and nodular septa (arrows). (c) Photomicrograph (original magnification, x175; hematoxylin-eosin stain) reveals typical features of a lipoma-like atypical lipomatous tumor/well-differentiated liposarcoma with largely mature adipocytes (A), only mild atypia (arrows), and thick septa (S).

 

View larger version (127K): [in a new window]   Figure 5a.  Retroperitoneal well-differentiated liposarcoma in a 60-year-old man with a history of increasing abdominal girth. (a) CT scan shows a large retroperitoneal and abdominal mass composed of fat (F) with Hounsfield (HU) measurements of –80 to –120. There are multiple thick septa (arrowheads) and a posterior component (*) with mildly higher attenuation (320 to 335 HU). (b, c) Photographs of the gross specimen (b) and axially sectioned specimen (c) reveal that the large mass is predominantly composed of fat (*) with some heterogeneous intermixed myxoid areas (m) that correspond to the imaging findings.

 

View larger version (126K): [in a new window]   Figure 5b.  Retroperitoneal well-differentiated liposarcoma in a 60-year-old man with a history of increasing abdominal girth. (a) CT scan shows a large retroperitoneal and abdominal mass composed of fat (F) with Hounsfield (HU) measurements of –80 to –120. There are multiple thick septa (arrowheads) and a posterior component (*) with mildly higher attenuation (320 to 335 HU). (b, c) Photographs of the gross specimen (b) and axially sectioned specimen (c) reveal that the large mass is predominantly composed of fat (*) with some heterogeneous intermixed myxoid areas (m) that correspond to the imaging findings.

 

View larger version (102K): [in a new window]   Figure 5c.  Retroperitoneal well-differentiated liposarcoma in a 60-year-old man with a history of increasing abdominal girth. (a) CT scan shows a large retroperitoneal and abdominal mass composed of fat (F) with Hounsfield (HU) measurements of –80 to –120. There are multiple thick septa (arrowheads) and a posterior component (*) with mildly higher attenuation (320 to 335 HU). (b, c) Photographs of the gross specimen (b) and axially sectioned specimen (c) reveal that the large mass is predominantly composed of fat (*) with some heterogeneous intermixed myxoid areas (m) that correspond to the imaging findings.

 

View larger version (104K): [in a new window]   Figure 6a.  Dedifferentiated liposarcoma of the thigh in a 72-year-old man with a 10-year history of a slowly enlarging mass with recent rapid growth. (a) Anteroposterior radiograph of the thigh shows a large mass with calcified areas (C), radiolucent adipose regions (A), and a superior soft-tissue component (S) that correspond to the recent area of rapid growth. (b, c) Sagittal T1-weighted (500/16) (b) and T2-weighted (1600/120) (c) MR images reveal that the mass is composed largely of tissue isointense relative to subcutaneous fat (*) but also contains thick septa (arrows). There is also a large nodular, nonlipomatous component (O) with nonspecific characteristics of low signal intensity with T1-weighting and heterogeneous intermediate to high signal intensity with T2-weighting. (d) Photograph of the resected gross specimen shows a lipomatous mass (L) with a nodular hemorrhagic component (H). (e) Photomicrograph (original magnification, x200; hematoxylin-eosin stain) reveals well-differentiated liposarcoma (L) and a high-grade dedifferentiated spindle cell component (M) (malignant fibrous histiocytoma-like), findings that correspond to the imaging appearances. The calcified area (not shown) represented metaplastic ossification in the well-differentiated liposarcoma.

 

View larger version (163K): [in a new window]   Figure 6b.  Dedifferentiated liposarcoma of the thigh in a 72-year-old man with a 10-year history of a slowly enlarging mass with recent rapid growth. (a) Anteroposterior radiograph of the thigh shows a large mass with calcified areas (C), radiolucent adipose regions (A), and a superior soft-tissue component (S) that correspond to the recent area of rapid growth. (b, c) Sagittal T1-weighted (500/16) (b) and T2-weighted (1600/120) (c) MR images reveal that the mass is composed largely of tissue isointense relative to subcutaneous fat (*) but also contains thick septa (arrows). There is also a large nodular, nonlipomatous component (O) with nonspecific characteristics of low signal intensity with T1-weighting and heterogeneous intermediate to high signal intensity with T2-weighting. (d) Photograph of the resected gross specimen shows a lipomatous mass (L) with a nodular hemorrhagic component (H). (e) Photomicrograph (original magnification, x200; hematoxylin-eosin stain) reveals well-differentiated liposarcoma (L) and a high-grade dedifferentiated spindle cell component (M) (malignant fibrous histiocytoma-like), findings that correspond to the imaging appearances. The calcified area (not shown) represented metaplastic ossification in the well-differentiated liposarcoma.

 

View larger version (159K): [in a new window]   Figure 6c.  Dedifferentiated liposarcoma of the thigh in a 72-year-old man with a 10-year history of a slowly enlarging mass with recent rapid growth. (a) Anteroposterior radiograph of the thigh shows a large mass with calcified areas (C), radiolucent adipose regions (A), and a superior soft-tissue component (S) that correspond to the recent area of rapid growth. (b, c) Sagittal T1-weighted (500/16) (b) and T2-weighted (1600/120) (c) MR images reveal that the mass is composed largely of tissue isointense relative to subcutaneous fat (*) but also contains thick septa (arrows). There is also a large nodular, nonlipomatous component (O) with nonspecific characteristics of low signal intensity with T1-weighting and heterogeneous intermediate to high signal intensity with T2-weighting. (d) Photograph of the resected gross specimen shows a lipomatous mass (L) with a nodular hemorrhagic component (H). (e) Photomicrograph (original magnification, x200; hematoxylin-eosin stain) reveals well-differentiated liposarcoma (L) and a high-grade dedifferentiated spindle cell component (M) (malignant fibrous histiocytoma-like), findings that correspond to the imaging appearances. The calcified area (not shown) represented metaplastic ossification in the well-differentiated liposarcoma.

 

View larger version (109K): [in a new window]   Figure 6d.  Dedifferentiated liposarcoma of the thigh in a 72-year-old man with a 10-year history of a slowly enlarging mass with recent rapid growth. (a) Anteroposterior radiograph of the thigh shows a large mass with calcified areas (C), radiolucent adipose regions (A), and a superior soft-tissue component (S) that correspond to the recent area of rapid growth. (b, c) Sagittal T1-weighted (500/16) (b) and T2-weighted (1600/120) (c) MR images reveal that the mass is composed largely of tissue isointense relative to subcutaneous fat (*) but also contains thick septa (arrows). There is also a large nodular, nonlipomatous component (O) with nonspecific characteristics of low signal intensity with T1-weighting and heterogeneous intermediate to high signal intensity with T2-weighting. (d) Photograph of the resected gross specimen shows a lipomatous mass (L) with a nodular hemorrhagic component (H). (e) Photomicrograph (original magnification, x200; hematoxylin-eosin stain) reveals well-differentiated liposarcoma (L) and a high-grade dedifferentiated spindle cell component (M) (malignant fibrous histiocytoma-like), findings that correspond to the imaging appearances. The calcified area (not shown) represented metaplastic ossification in the well-differentiated liposarcoma.

 

View larger version (143K): [in a new window]   Figure 6e.  Dedifferentiated liposarcoma of the thigh in a 72-year-old man with a 10-year history of a slowly enlarging mass with recent rapid growth. (a) Anteroposterior radiograph of the thigh shows a large mass with calcified areas (C), radiolucent adipose regions (A), and a superior soft-tissue component (S) that correspond to the recent area of rapid growth. (b, c) Sagittal T1-weighted (500/16) (b) and T2-weighted (1600/120) (c) MR images reveal that the mass is composed largely of tissue isointense relative to subcutaneous fat (*) but also contains thick septa (arrows). There is also a large nodular, nonlipomatous component (O) with nonspecific characteristics of low signal intensity with T1-weighting and heterogeneous intermediate to high signal intensity with T2-weighting. (d) Photograph of the resected gross specimen shows a lipomatous mass (L) with a nodular hemorrhagic component (H). (e) Photomicrograph (original magnification, x200; hematoxylin-eosin stain) reveals well-differentiated liposarcoma (L) and a high-grade dedifferentiated spindle cell component (M) (malignant fibrous histiocytoma-like), findings that correspond to the imaging appearances. The calcified area (not shown) represented metaplastic ossification in the well-differentiated liposarcoma.

 

View larger version (116K): [in a new window]   Figure 7a.  Dedifferentiated liposarcoma of the retroperitoneum in a 67-year-old man who presented with an enlarging abdominal mass. (a) Abdominal radiograph from a barium enema study shows a large abdominal mass that displaces opacified bowel to the left. (b, c) CT images (b obtained at a higher level) reveal the large retroperitoneal and abdominal mass that has three components of differing attenuation, including a lipomatous region (L) with thick septa (arrows); a low-attenuation, high-water content component (W) also with thick septa (arrowheads); and a heterogeneous calcified area (C). (d) Photograph of the resected gross specimen demonstrates the large size of the mass (M). (e) Photograph of the sectioned gross specimen corresponds to the imaging features, with the yellow well-differentiated liposarcoma component (L) with thick septa (arrow), lobular chondrosarcomatous (dedifferentiated focus) region with calcification (C), and hemorrhagic region (H).

 

View larger version (158K): [in a new window]   Figure 7b.  Dedifferentiated liposarcoma of the retroperitoneum in a 67-year-old man who presented with an enlarging abdominal mass. (a) Abdominal radiograph from a barium enema study shows a large abdominal mass that displaces opacified bowel to the left. (b, c) CT images (b obtained at a higher level) reveal the large retroperitoneal and abdominal mass that has three components of differing attenuation, including a lipomatous region (L) with thick septa (arrows); a low-attenuation, high-water content component (W) also with thick septa (arrowheads); and a heterogeneous calcified area (C). (d) Photograph of the resected gross specimen demonstrates the large size of the mass (M). (e) Photograph of the sectioned gross specimen corresponds to the imaging features, with the yellow well-differentiated liposarcoma component (L) with thick septa (arrow), lobular chondrosarcomatous (dedifferentiated focus) region with calcification (C), and hemorrhagic region (H).

 

View larger version (141K): [in a new window]   Figure 7c.  Dedifferentiated liposarcoma of the retroperitoneum in a 67-year-old man who presented with an enlarging abdominal mass. (a) Abdominal radiograph from a barium enema study shows a large abdominal mass that displaces opacified bowel to the left. (b, c) CT images (b obtained at a higher level) reveal the large retroperitoneal and abdominal mass that has three components of differing attenuation, including a lipomatous region (L) with thick septa (arrows); a low-attenuation, high-water content component (W) also with thick septa (arrowheads); and a heterogeneous calcified area (C). (d) Photograph of the resected gross specimen demonstrates the large size of the mass (M). (e) Photograph of the sectioned gross specimen corresponds to the imaging features, with the yellow well-differentiated liposarcoma component (L) with thick septa (arrow), lobular chondrosarcomatous (dedifferentiated focus) region with calcification (C), and hemorrhagic region (H).

 

View larger version (108K): [in a new window]   Figure 7d.  Dedifferentiated liposarcoma of the retroperitoneum in a 67-year-old man who presented with an enlarging abdominal mass. (a) Abdominal radiograph from a barium enema study shows a large abdominal mass that displaces opacified bowel to the left. (b, c) CT images (b obtained at a higher level) reveal the large retroperitoneal and abdominal mass that has three components of differing attenuation, including a lipomatous region (L) with thick septa (arrows); a low-attenuation, high-water content component (W) also with thick septa (arrowheads); and a heterogeneous calcified area (C). (d) Photograph of the resected gross specimen demonstrates the large size of the mass (M). (e) Photograph of the sectioned gross specimen corresponds to the imaging features, with the yellow well-differentiated liposarcoma component (L) with thick septa (arrow), lobular chondrosarcomatous (dedifferentiated focus) region with calcification (C), and hemorrhagic region (H).

 

View larger version (112K): [in a new window]   Figure 7e.  Dedifferentiated liposarcoma of the retroperitoneum in a 67-year-old man who presented with an enlarging abdominal mass. (a) Abdominal radiograph from a barium enema study shows a large abdominal mass that displaces opacified bowel to the left. (b, c) CT images (b obtained at a higher level) reveal the large retroperitoneal and abdominal mass that has three components of differing attenuation, including a lipomatous region (L) with thick septa (arrows); a low-attenuation, high-water content component (W) also with thick septa (arrowheads); and a heterogeneous calcified area (C). (d) Photograph of the resected gross specimen demonstrates the large size of the mass (M). (e) Photograph of the sectioned gross specimen corresponds to the imaging features, with the yellow well-differentiated liposarcoma component (L) with thick septa (arrow), lobular chondrosarcomatous (dedifferentiated focus) region with calcification (C), and hemorrhagic region (H).

 

View larger version (87K): [in a new window]   Figure 8a.  Myxoid liposarcoma of the popliteal region in a 60-year-old woman with a painless, slowly growing (over 6 years) mass that had been clinically diagnosed as a popliteal cyst. (a) Lateral radiograph shows a large, nonspecific, soft-tissue mass without radiolucent fat (*). (b) Axial sonogram reveals a heterogeneous mass with both low-echogenicity areas (L), corresponding to myxoid tissue, and regions of higher echogenicity (H). It is not possible to definitively identify fat, although the lesion is not cystic, is not in the expected location of a popliteal cyst, and does not show a neck of fluid extending toward the joint. (c–e) Sagittal T1-weighted (500/20) MR images obtained before (c) and after (d) contrast enhancement and axial T2-weighted (2500/90) (e) MR image show a large heterogeneous intermuscular popliteal mass (arrowheads). The mass is deeper than expected for a Baker cyst, and no neck of fluid extending to the joint is seen. The predominant signal intensity is that of a high-water content mass (M) with low signal intensity with T1-weighting and high signal intensity with T2-weighting. However, focal areas in the septa (arrows in c) and several small (<10% of the tumor volume) nodular regions (F) are isointense relative to subcutaneous fat. After administration of contrast agent, thick and nodular peripheral and septal enhancement is seen, most prominent inferiorly (arrows in d). (f, g) Photograph of the axially sectioned gross specimen (f) and photomicrograph (original magnification, x200, hematoxylin-eosin stain) (g) show the high-water content myxoid regions (M) and adipose areas (arrows) corresponding to the imaging findings.

 

View larger version (133K): [in a new window]   Figure 8b.  Myxoid liposarcoma of the popliteal region in a 60-year-old woman with a painless, slowly growing (over 6 years) mass that had been clinically diagnosed as a popliteal cyst. (a) Lateral radiograph shows a large, nonspecific, soft-tissue mass without radiolucent fat (*). (b) Axial sonogram reveals a heterogeneous mass with both low-echogenicity areas (L), corresponding to myxoid tissue, and regions of higher echogenicity (H). It is not possible to definitively identify fat, although the lesion is not cystic, is not in the expected location of a popliteal cyst, and does not show a neck of fluid extending toward the joint. (c–e) Sagittal T1-weighted (500/20) MR images obtained before (c) and after (d) contrast enhancement and axial T2-weighted (2500/90) (e) MR image show a large heterogeneous intermuscular popliteal mass (arrowheads). The mass is deeper than expected for a Baker cyst, and no neck of fluid extending to the joint is seen. The predominant signal intensity is that of a high-water content mass (M) with low signal intensity with T1-weighting and high signal intensity with T2-weighting. However, focal areas in the septa (arrows in c) and several small (<10% of the tumor volume) nodular regions (F) are isointense relative to subcutaneous fat. After administration of contrast agent, thick and nodular peripheral and septal enhancement is seen, most prominent inferiorly (arrows in d). (f, g) Photograph of the axially sectioned gross specimen (f) and photomicrograph (original magnification, x200, hematoxylin-eosin stain) (g) show the high-water content myxoid regions (M) and adipose areas (arrows) corresponding to the imaging findings.

 

View larger version (90K): [in a new window]   Figure 8c.  Myxoid liposarcoma of the popliteal region in a 60-year-old woman with a painless, slowly growing (over 6 years) mass that had been clinically diagnosed as a popliteal cyst. (a) Lateral radiograph shows a large, nonspecific, soft-tissue mass without radiolucent fat (*). (b) Axial sonogram reveals a heterogeneous mass with both low-echogenicity areas (L), corresponding to myxoid tissue, and regions of higher echogenicity (H). It is not possible to definitively identify fat, although the lesion is not cystic, is not in the expected location of a popliteal cyst, and does not show a neck of fluid extending toward the joint. (c–e) Sagittal T1-weighted (500/20) MR images obtained before (c) and after (d) contrast enhancement and axial T2-weighted (2500/90) (e) MR image show a large heterogeneous intermuscular popliteal mass (arrowheads). The mass is deeper than expected for a Baker cyst, and no neck of fluid extending to the joint is seen. The predominant signal intensity is that of a high-water content mass (M) with low signal intensity with T1-weighting and high signal intensity with T2-weighting. However, focal areas in the septa (arrows in c) and several small (<10% of the tumor volume) nodular regions (F) are isointense relative to subcutaneous fat. After administration of contrast agent, thick and nodular peripheral and septal enhancement is seen, most prominent inferiorly (arrows in d). (f, g) Photograph of the axially sectioned gross specimen (f) and photomicrograph (original magnification, x200, hematoxylin-eosin stain) (g) show the high-water content myxoid regions (M) and adipose areas (arrows) corresponding to the imaging findings.

 

View larger version (87K): [in a new window]   Figure 8d.  Myxoid liposarcoma of the popliteal region in a 60-year-old woman with a painless, slowly growing (over 6 years) mass that had been clinically diagnosed as a popliteal cyst. (a) Lateral radiograph shows a large, nonspecific, soft-tissue mass without radiolucent fat (*). (b) Axial sonogram reveals a heterogeneous mass with both low-echogenicity areas (L), corresponding to myxoid tissue, and regions of higher echogenicity (H). It is not possible to definitively identify fat, although the lesion is not cystic, is not in the expected location of a popliteal cyst, and does not show a neck of fluid extending toward the joint. (c–e) Sagittal T1-weighted (500/20) MR images obtained before (c) and after (d) contrast enhancement and axial T2-weighted (2500/90) (e) MR image show a large heterogeneous intermuscular popliteal mass (arrowheads). The mass is deeper than expected for a Baker cyst, and no neck of fluid extending to the joint is seen. The predominant signal intensity is that of a high-water content mass (M) with low signal intensity with T1-weighting and high signal intensity with T2-weighting. However, focal areas in the septa (arrows in c) and several small (<10% of the tumor volume) nodular regions (F) are isointense relative to subcutaneous fat. After administration of contrast agent, thick and nodular peripheral and septal enhancement is seen, most prominent inferiorly (arrows in d). (f, g) Photograph of the axially sectioned gross specimen (f) and photomicrograph (original magnification, x200, hematoxylin-eosin stain) (g) show the high-water content myxoid regions (M) and adipose areas (arrows) corresponding to the imaging findings.

 

View larger version (96K): [in a new window]   Figure 8e.  Myxoid liposarcoma of the popliteal region in a 60-year-old woman with a painless, slowly growing (over 6 years) mass that had been clinically diagnosed as a popliteal cyst. (a) Lateral radiograph shows a large, nonspecific, soft-tissue mass without radiolucent fat (*). (b) Axial sonogram reveals a heterogeneous mass with both low-echogenicity areas (L), corresponding to myxoid tissue, and regions of higher echogenicity (H). It is not possible to definitively identify fat, although the lesion is not cystic, is not in the expected location of a popliteal cyst, and does not show a neck of fluid extending toward the joint. (c–e) Sagittal T1-weighted (500/20) MR images obtained before (c) and after (d) contrast enhancement and axial T2-weighted (2500/90) (e) MR image show a large heterogeneous intermuscular popliteal mass (arrowheads). The mass is deeper than expected for a Baker cyst, and no neck of fluid extending to the joint is seen. The predominant signal intensity is that of a high-water content mass (M) with low signal intensity with T1-weighting and high signal intensity with T2-weighting. However, focal areas in the septa (arrows in c) and several small (<10% of the tumor volume) nodular regions (F) are isointense relative to subcutaneous fat. After administration of contrast agent, thick and nodular peripheral and septal enhancement is seen, most prominent inferiorly (arrows in d). (f, g) Photograph of the axially sectioned gross specimen (f) and photomicrograph (original magnification, x200, hematoxylin-eosin stain) (g) show the high-water content myxoid regions (M) and adipose areas (arrows) corresponding to the imaging findings.

 

View larger version (117K): [in a new window]   Figure 8f.  Myxoid liposarcoma of the popliteal region in a 60-year-old woman with a painless, slowly growing (over 6 years) mass that had been clinically diagnosed as a popliteal cyst. (a) Lateral radiograph shows a large, nonspecific, soft-tissue mass without radiolucent fat (*). (b) Axial sonogram reveals a heterogeneous mass with both low-echogenicity areas (L), corresponding to myxoid tissue, and regions of higher echogenicity (H). It is not possible to definitively identify fat, although the lesion is not cystic, is not in the expected location of a popliteal cyst, and does not show a neck of fluid extending toward the joint. (c–e) Sagittal T1-weighted (500/20) MR images obtained before (c) and after (d) contrast enhancement and axial T2-weighted (2500/90) (e) MR image show a large heterogeneous intermuscular popliteal mass (arrowheads). The mass is deeper than expected for a Baker cyst, and no neck of fluid extending to the joint is seen. The predominant signal intensity is that of a high-water content mass (M) with low signal intensity with T1-weighting and high signal intensity with T2-weighting. However, focal areas in the septa (arrows in c) and several small (<10% of the tumor volume) nodular regions (F) are isointense relative to subcutaneous fat. After administration of contrast agent, thick and nodular peripheral and septal enhancement is seen, most prominent inferiorly (arrows in d). (f, g) Photograph of the axially sectioned gross specimen (f) and photomicrograph (original magnification, x200, hematoxylin-eosin stain) (g) show the high-water content myxoid regions (M) and adipose areas (arrows) corresponding to the imaging findings.

 

View larger version (133K): [in a new window]   Figure 8g.  Myxoid liposarcoma of the popliteal region in a 60-year-old woman with a painless, slowly growing (over 6 years) mass that had been clinically diagnosed as a popliteal cyst. (a) Lateral radiograph shows a large, nonspecific, soft-tissue mass without radiolucent fat (*). (b) Axial sonogram reveals a heterogeneous mass with both low-echogenicity areas (L), corresponding to myxoid tissue, and regions of higher echogenicity (H). It is not possible to definitively identify fat, although the lesion is not cystic, is not in the expected location of a popliteal cyst, and does not show a neck of fluid extending toward the joint. (c–e) Sagittal T1-weighted (500/20) MR images obtained before (c) and after (d) contrast enhancement and axial T2-weighted (2500/90) (e) MR image show a large heterogeneous intermuscular popliteal mass (arrowheads). The mass is deeper than expected for a Baker cyst, and no neck of fluid extending to the joint is seen. The predominant signal intensity is that of a high-water content mass (M) with low signal intensity with T1-weighting and high signal intensity with T2-weighting. However, focal areas in the septa (arrows in c) and several small (<10% of the tumor volume) nodular regions (F) are isointense relative to subcutaneous fat. After administration of contrast agent, thick and nodular peripheral and septal enhancement is seen, most prominent inferiorly (arrows in d). (f, g) Photograph of the axially sectioned gross specimen (f) and photomicrograph (original magnification, x200, hematoxylin-eosin stain) (g) show the high-water content myxoid regions (M) and adipose areas (arrows) corresponding to the imaging findings.

 

View larger version (140K): [in a new window]   Figure 9a.  Myxoid liposarcoma in the distal thigh in a 16-year-old boy with a slowly enlarging mass with subsequent development of pleural metastasis. (a) CT scan of the distal thigh shows an intermuscular mass with predominant attenuation lower than that of muscle (*) that displaces adjacent muscle (M). Several round foci of very low attenuation (arrows) similar to that of fat are also seen. (b, c) Axial T1-weighted (600/20) (b) and T2-weighted (2000/80) (c) MR images reveal an intermuscular posterior compartment mass (*) of predominantly high-water content (low signal intensity with T1-weighting and very high signal intensity with T2-weighting). Several nodular foci (arrows) of tissue similar or identical to subcutaneous fat are identified. (d) Photograph of the axially sectioned gross specimen demonstrates pathologic features identical to those seen at imaging: high-water content myxoid areas (m) and focal nodules containing fat (arrows). (e, f) Chest radiograph (e) and CT scan (f) obtained several years later reveal a pleural-based metastasis (P). The low attenuation seen on the CT scan reflects the high-water content myxoid tissue.

 

View larger version (130K): [in a new window]   Figure 9b.  Myxoid liposarcoma in the distal thigh in a 16-year-old boy with a slowly enlarging mass with subsequent development of pleural metastasis. (a) CT scan of the distal thigh shows an intermuscular mass with predominant attenuation lower than that of muscle (*) that displaces adjacent muscle (M). Several round foci of very low attenuation (arrows) similar to that of fat are also seen. (b, c) Axial T1-weighted (600/20) (b) and T2-weighted (2000/80) (c) MR images reveal an intermuscular posterior compartment mass (*) of predominantly high-water content (low signal intensity with T1-weighting and very high signal intensity with T2-weighting). Several nodular foci (arrows) of tissue similar or identical to subcutaneous fat are identified. (d) Photograph of the axially sectioned gross specimen demonstrates pathologic features identical to those seen at imaging: high-water content myxoid areas (m) and focal nodules containing fat (arrows). (e, f) Chest radiograph (e) and CT scan (f) obtained several years later reveal a pleural-based metastasis (P). The low attenuation seen on the CT scan reflects the high-water content myxoid tissue.

 

View larger version (157K): [in a new window]   Figure 9c.  Myxoid liposarcoma in the distal thigh in a 16-year-old boy with a slowly enlarging mass with subsequent development of pleural metastasis. (a) CT scan of the distal thigh shows an intermuscular mass with predominant attenuation lower than that of muscle (*) that displaces adjacent muscle (M). Several round foci of very low attenuation (arrows) similar to that of fat are also seen. (b, c) Axial T1-weighted (600/20) (b) and T2-weighted (2000/80) (c) MR images reveal an intermuscular posterior compartment mass (*) of predominantly high-water content (low signal intensity with T1-weighting and very high signal intensity with T2-weighting). Several nodular foci (arrows) of tissue similar or identical to subcutaneous fat are identified. (d) Photograph of the axially sectioned gross specimen demonstrates pathologic features identical to those seen at imaging: high-water content myxoid areas (m) and focal nodules containing fat (arrows). (e, f) Chest radiograph (e) and CT scan (f) obtained several years later reveal a pleural-based metastasis (P). The low attenuation seen on the CT scan reflects the high-water content myxoid tissue.

 

View larger version (121K): [in a new window]   Figure 9d.  Myxoid liposarcoma in the distal thigh in a 16-year-old boy with a slowly enlarging mass with subsequent development of pleural metastasis. (a) CT scan of the distal thigh shows an intermuscular mass with predominant attenuation lower than that of muscle (*) that displaces adjacent muscle (M). Several round foci of very low attenuation (arrows) similar to that of fat are also seen. (b, c) Axial T1-weighted (600/20) (b) and T2-weighted (2000/80) (c) MR images reveal an intermuscular posterior compartment mass (*) of predominantly high-water content (low signal intensity with T1-weighting and very high signal intensity with T2-weighting). Several nodular foci (arrows) of tissue similar or identical to subcutaneous fat are identified. (d) Photograph of the axially sectioned gross specimen demonstrates pathologic features identical to those seen at imaging: high-water content myxoid areas (m) and focal nodules containing fat (arrows). (e, f) Chest radiograph (e) and CT scan (f) obtained several years later reveal a pleural-based metastasis (P). The low attenuation seen on the CT scan reflects the high-water content myxoid tissue.

 

View larger version (131K): [in a new window]   Figure 9e.  Myxoid liposarcoma in the distal thigh in a 16-year-old boy with a slowly enlarging mass with subsequent development of pleural metastasis. (a) CT scan of the distal thigh shows an intermuscular mass with predominant attenuation lower than that of muscle (*) that displaces adjacent muscle (M). Several round foci of very low attenuation (arrows) similar to that of fat are also seen. (b, c) Axial T1-weighted (600/20) (b) and T2-weighted (2000/80) (c) MR images reveal an intermuscular posterior compartment mass (*) of predominantly high-water content (low signal intensity with T1-weighting and very high signal intensity with T2-weighting). Several nodular foci (arrows) of tissue similar or identical to subcutaneous fat are identified. (d) Photograph of the axially sectioned gross specimen demonstrates pathologic features identical to those seen at imaging: high-water content myxoid areas (m) and focal nodules containing fat (arrows). (e, f) Chest radiograph (e) and CT scan (f) obtained several years later reveal a pleural-based metastasis (P). The low attenuation seen on the CT scan reflects the high-water content myxoid tissue.

 

View larger version (113K): [in a new window]   Figure 9f.  Myxoid liposarcoma in the distal thigh in a 16-year-old boy with a slowly enlarging mass with subsequent development of pleural metastasis. (a) CT scan of the distal thigh shows an intermuscular mass with predominant attenuation lower than that of muscle (*) that displaces adjacent muscle (M). Several round foci of very low attenuation (arrows) similar to that of fat are also seen. (b, c) Axial T1-weighted (600/20) (b) and T2-weighted (2000/80) (c) MR images reveal an intermuscular posterior compartment mass (*) of predominantly high-water content (low signal intensity with T1-weighting and very high signal intensity with T2-weighting). Several nodular foci (arrows) of tissue similar or identical to subcutaneous fat are identified. (d) Photograph of the axially sectioned gross specimen demonstrates pathologic features identical to those seen at imaging: high-water content myxoid areas (m) and focal nodules containing fat (arrows). (e, f) Chest radiograph (e) and CT scan (f) obtained several years later reveal a pleural-based metastasis (P). The low attenuation seen on the CT scan reflects the high-water content myxoid tissue.

 

View larger version (157K): [in a new window]   Figure 10a.  Myxoid liposarcoma simulating a cyst in a