From the Archives of the AFIP 1
Imaging of Musculoskeletal Neurogenic Tumors: Radiologic-Pathologic Correlation
Mark D. Murphey, MD ,
W. Sean Smith, MD, 2,
Stacy E. Smith, MD ,
Mark J. Kransdorf, MD and
H. Thomas Temple, M, 3
1 From the Department of Radiologic Pathology, Armed Forces Institute of Pathology, 6825 16th Street NW, Bldg 54, Room M-133A, Washington, DC 20306 (M.D.M., W.S.S., S.E.S.); Departments of Radiology and Nuclear Medicine (M.D.M., W.S.S.) and Surgery (H.T.T.), Uniformed Services University of the Health Sciences, Bethesda, Md; Department of Radiology, University of Maryland School of Medicine, Baltimore (M.D.M., S.E.S.); Department of Surgery, Orthopedic Service, Walter Reed Army Medical Center, Washington, DC (H.T.T.); Department of Radiology, St Mary's Hospital, Richmond, Va (M.J.K.). Received April 8, 1999; revision requested April 26 and received May 28; accepted June 1. Presented as a scientific exhibit at the 1995 RSNA scientific assembly. Address reprint requests to M.D.M.
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Figure 1. Normal nerve structure. Photomicrograph (original magnification, approximately x20; Bielschowsky silver stain) of an axial section of normal sural nerve. Nerve is surrounded by epineurium (straight arrows). Bundles of nerve fibers (*) are surrounded by perineurium (curved arrows), creating a fascicular appearance. Adipose tissue (black arrowheads) and blood vessels (white arrowheads) are seen about the nerve.
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Figure 2. Normal nerve appearance at MR imaging. Axial T1-weighted (repetition time msec/echo time msec = 500/20) MR image of the upper thigh shows the normal sciatic nerve (arrows) with small circular low-signal-intensity areas (arrowheads) surrounded by a background of mildly higher-signal-intensity areas representing the fascicular structure of the normal nerve.
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Figure 3a. Traumatic neuromas that developed after a below-the-knee amputation in a 33-year-old man. (a) Coronal T1-weighted (500/16) MR image shows two masses. The proximal neuroma (terminal type) has an entering tubular tibial nerve (arrowhead) ending in a bulbous expansion (*). Spindle neuroma resulting from chronic irritation of a small superficial nerve (not visible as a distinct structure) at the prosthesis attachment is seen as a nonspecific mass (arrows). (b) On an axial T2-weighted (4,300/126) image, the proximal lesion has high signal intensity with a fascicular pattern (arrow).
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Figure 3b. Traumatic neuromas that developed after a below-the-knee amputation in a 33-year-old man. (a) Coronal T1-weighted (500/16) MR image shows two masses. The proximal neuroma (terminal type) has an entering tubular tibial nerve (arrowhead) ending in a bulbous expansion (*). Spindle neuroma resulting from chronic irritation of a small superficial nerve (not visible as a distinct structure) at the prosthesis attachment is seen as a nonspecific mass (arrows). (b) On an axial T2-weighted (4,300/126) image, the proximal lesion has high signal intensity with a fascicular pattern (arrow).
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Figure 4a. Morton neuroma in a 45-year-old woman. (a) Short axis T1-weighted (750/15) MR image shows a 6-mm mass (*) in the interspace between the third and fourth metatarsals at the level of the metatarsal head. (b, c) Short axis fat-suppressed contrast material-enhanced T1-weighted (700/15) MR (b) and power Doppler US (c) images show marked enhancement and increased vascularity of the lesion (*). (d) Photograph of the resected specimen shows the entering plantar digital nerve (arrowheads) and the mass (arrows) distally representing perineural fibrosis.
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Figure 4b. Morton neuroma in a 45-year-old woman. (a) Short axis T1-weighted (750/15) MR image shows a 6-mm mass (*) in the interspace between the third and fourth metatarsals at the level of the metatarsal head. (b, c) Short axis fat-suppressed contrast material-enhanced T1-weighted (700/15) MR (b) and power Doppler US (c) images show marked enhancement and increased vascularity of the lesion (*). (d) Photograph of the resected specimen shows the entering plantar digital nerve (arrowheads) and the mass (arrows) distally representing perineural fibrosis.
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Figure 4c. Morton neuroma in a 45-year-old woman. (a) Short axis T1-weighted (750/15) MR image shows a 6-mm mass (*) in the interspace between the third and fourth metatarsals at the level of the metatarsal head. (b, c) Short axis fat-suppressed contrast material-enhanced T1-weighted (700/15) MR (b) and power Doppler US (c) images show marked enhancement and increased vascularity of the lesion (*). (d) Photograph of the resected specimen shows the entering plantar digital nerve (arrowheads) and the mass (arrows) distally representing perineural fibrosis.
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Figure 4d. Morton neuroma in a 45-year-old woman. (a) Short axis T1-weighted (750/15) MR image shows a 6-mm mass (*) in the interspace between the third and fourth metatarsals at the level of the metatarsal head. (b, c) Short axis fat-suppressed contrast material-enhanced T1-weighted (700/15) MR (b) and power Doppler US (c) images show marked enhancement and increased vascularity of the lesion (*). (d) Photograph of the resected specimen shows the entering plantar digital nerve (arrowheads) and the mass (arrows) distally representing perineural fibrosis.
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Figure 5. Morton neuroma in a 31-year-old man. T2-weighted (2,500/90) MR image shows a 4-mm mass (*) between the third and fourth metatarsal heads. Conspicuity of the lesion is low (cf Fig 4a) due to minimal differences in signal intensity of surrounding fat and the lesion.
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Figure 6a. Neural fibrolipoma in a 34-year-old man with macrodactyly. (a, b) Photograph (a) and anteroposterior radiograph (b) of the hand show soft-tissue and osseous enlargement (in length and width) of the second and third digits with ulnar deviation and secondary degenerative changes (arrowhead in b). (c, d) Axial T1-weighted (500/20) MR images of the wrist (c) and phalanges (d) reveal adipose tissue causing thickened nerve, surrounding fascicles (arrowheads) both proximally (median nerve) and distally (interdigital nerve branches), and overgrowth of the second and third digits with predominance of fat (arrow). (e) Longitudinal US scan of the wrist shows multiple elongated, enlarged median nerve fascicles (arrowheads). (f) Intraoperative photograph of wrist dissection shows a diffusely thickened, yellow median nerve resulting from the neural fibrolipoma (arrow). (g, h) Photograph of a coronally sectioned whole-mount specimen (hematoxylin-eosin stain) (g) of the second digit and photomicrograph (h) (original magnification, x200; hematoxylin-eosin stain) demonstrate osseous and soft-tissue hypertrophy with predominance of fat (*) surrounding nerve fascicles (arrow).
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Figure 6b. Neural fibrolipoma in a 34-year-old man with macrodactyly. (a, b) Photograph (a) and anteroposterior radiograph (b) of the hand show soft-tissue and osseous enlargement (in length and width) of the second and third digits with ulnar deviation and secondary degenerative changes (arrowhead in b). (c, d) Axial T1-weighted (500/20) MR images of the wrist (c) and phalanges (d) reveal adipose tissue causing thickened nerve, surrounding fascicles (arrowheads) both proximally (median nerve) and distally (interdigital nerve branches), and overgrowth of the second and third digits with predominance of fat (arrow). (e) Longitudinal US scan of the wrist shows multiple elongated, enlarged median nerve fascicles (arrowheads). (f) Intraoperative photograph of wrist dissection shows a diffusely thickened, yellow median nerve resulting from the neural fibrolipoma (arrow). (g, h) Photograph of a coronally sectioned whole-mount specimen (hematoxylin-eosin stain) (g) of the second digit and photomicrograph (h) (original magnification, x200; hematoxylin-eosin stain) demonstrate osseous and soft-tissue hypertrophy with predominance of fat (*) surrounding nerve fascicles (arrow).
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Figure 6c. Neural fibrolipoma in a 34-year-old man with macrodactyly. (a, b) Photograph (a) and anteroposterior radiograph (b) of the hand show soft-tissue and osseous enlargement (in length and width) of the second and third digits with ulnar deviation and secondary degenerative changes (arrowhead in b). (c, d) Axial T1-weighted (500/20) MR images of the wrist (c) and phalanges (d) reveal adipose tissue causing thickened nerve, surrounding fascicles (arrowheads) both proximally (median nerve) and distally (interdigital nerve branches), and overgrowth of the second and third digits with predominance of fat (arrow). (e) Longitudinal US scan of the wrist shows multiple elongated, enlarged median nerve fascicles (arrowheads). (f) Intraoperative photograph of wrist dissection shows a diffusely thickened, yellow median nerve resulting from the neural fibrolipoma (arrow). (g, h) Photograph of a coronally sectioned whole-mount specimen (hematoxylin-eosin stain) (g) of the second digit and photomicrograph (h) (original magnification, x200; hematoxylin-eosin stain) demonstrate osseous and soft-tissue hypertrophy with predominance of fat (*) surrounding nerve fascicles (arrow).
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Figure 6d. Neural fibrolipoma in a 34-year-old man with macrodactyly. (a, b) Photograph (a) and anteroposterior radiograph (b) of the hand show soft-tissue and osseous enlargement (in length and width) of the second and third digits with ulnar deviation and secondary degenerative changes (arrowhead in b). (c, d) Axial T1-weighted (500/20) MR images of the wrist (c) and phalanges (d) reveal adipose tissue causing thickened nerve, surrounding fascicles (arrowheads) both proximally (median nerve) and distally (interdigital nerve branches), and overgrowth of the second and third digits with predominance of fat (arrow). (e) Longitudinal US scan of the wrist shows multiple elongated, enlarged median nerve fascicles (arrowheads). (f) Intraoperative photograph of wrist dissection shows a diffusely thickened, yellow median nerve resulting from the neural fibrolipoma (arrow). (g, h) Photograph of a coronally sectioned whole-mount specimen (hematoxylin-eosin stain) (g) of the second digit and photomicrograph (h) (original magnification, x200; hematoxylin-eosin stain) demonstrate osseous and soft-tissue hypertrophy with predominance of fat (*) surrounding nerve fascicles (arrow).
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Figure 6e. Neural fibrolipoma in a 34-year-old man with macrodactyly. (a, b) Photograph (a) and anteroposterior radiograph (b) of the hand show soft-tissue and osseous enlargement (in length and width) of the second and third digits with ulnar deviation and secondary degenerative changes (arrowhead in b). (c, d) Axial T1-weighted (500/20) MR images of the wrist (c) and phalanges (d) reveal adipose tissue causing thickened nerve, surrounding fascicles (arrowheads) both proximally (median nerve) and distally (interdigital nerve branches), and overgrowth of the second and third digits with predominance of fat (arrow). (e) Longitudinal US scan of the wrist shows multiple elongated, enlarged median nerve fascicles (arrowheads). (f) Intraoperative photograph of wrist dissection shows a diffusely thickened, yellow median nerve resulting from the neural fibrolipoma (arrow). (g, h) Photograph of a coronally sectioned whole-mount specimen (hematoxylin-eosin stain) (g) of the second digit and photomicrograph (h) (original magnification, x200; hematoxylin-eosin stain) demonstrate osseous and soft-tissue hypertrophy with predominance of fat (*) surrounding nerve fascicles (arrow).
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Figure 6f. Neural fibrolipoma in a 34-year-old man with macrodactyly. (a, b) Photograph (a) and anteroposterior radiograph (b) of the hand show soft-tissue and osseous enlargement (in length and width) of the second and third digits with ulnar deviation and secondary degenerative changes (arrowhead in b). (c, d) Axial T1-weighted (500/20) MR images of the wrist (c) and phalanges (d) reveal adipose tissue causing thickened nerve, surrounding fascicles (arrowheads) both proximally (median nerve) and distally (interdigital nerve branches), and overgrowth of the second and third digits with predominance of fat (arrow). (e) Longitudinal US scan of the wrist shows multiple elongated, enlarged median nerve fascicles (arrowheads). (f) Intraoperative photograph of wrist dissection shows a diffusely thickened, yellow median nerve resulting from the neural fibrolipoma (arrow). (g, h) Photograph of a coronally sectioned whole-mount specimen (hematoxylin-eosin stain) (g) of the second digit and photomicrograph (h) (original magnification, x200; hematoxylin-eosin stain) demonstrate osseous and soft-tissue hypertrophy with predominance of fat (*) surrounding nerve fascicles (arrow).
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Figure 6g. Neural fibrolipoma in a 34-year-old man with macrodactyly. (a, b) Photograph (a) and anteroposterior radiograph (b) of the hand show soft-tissue and osseous enlargement (in length and width) of the second and third digits with ulnar deviation and secondary degenerative changes (arrowhead in b). (c, d) Axial T1-weighted (500/20) MR images of the wrist (c) and phalanges (d) reveal adipose tissue causing thickened nerve, surrounding fascicles (arrowheads) both proximally (median nerve) and distally (interdigital nerve branches), and overgrowth of the second and third digits with predominance of fat (arrow). (e) Longitudinal US scan of the wrist shows multiple elongated, enlarged median nerve fascicles (arrowheads). (f) Intraoperative photograph of wrist dissection shows a diffusely thickened, yellow median nerve resulting from the neural fibrolipoma (arrow). (g, h) Photograph of a coronally sectioned whole-mount specimen (hematoxylin-eosin stain) (g) of the second digit and photomicrograph (h) (original magnification, x200; hematoxylin-eosin stain) demonstrate osseous and soft-tissue hypertrophy with predominance of fat (*) surrounding nerve fascicles (arrow).
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Figure 6h. Neural fibrolipoma in a 34-year-old man with macrodactyly. (a, b) Photograph (a) and anteroposterior radiograph (b) of the hand show soft-tissue and osseous enlargement (in length and width) of the second and third digits with ulnar deviation and secondary degenerative changes (arrowhead in b). (c, d) Axial T1-weighted (500/20) MR images of the wrist (c) and phalanges (d) reveal adipose tissue causing thickened nerve, surrounding fascicles (arrowheads) both proximally (median nerve) and distally (interdigital nerve branches), and overgrowth of the second and third digits with predominance of fat (arrow). (e) Longitudinal US scan of the wrist shows multiple elongated, enlarged median nerve fascicles (arrowheads). (f) Intraoperative photograph of wrist dissection shows a diffusely thickened, yellow median nerve resulting from the neural fibrolipoma (arrow). (g, h) Photograph of a coronally sectioned whole-mount specimen (hematoxylin-eosin stain) (g) of the second digit and photomicrograph (h) (original magnification, x200; hematoxylin-eosin stain) demonstrate osseous and soft-tissue hypertrophy with predominance of fat (*) surrounding nerve fascicles (arrow).
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Figure 7a. Nerve sheath ganglion in a 25-year-old man with peroneal nerve distribution symptoms. (a, b) Axial T1-weighted (600/20) (a) and fat-suppressed T2-weighted (4,666/90) (b) MR images show a fluid-appearing mass (arrowheads) adjacent to the anterolateral proximal fibula and peroneal nerve (arrow). (c, d) Intraoperative photograph (c) and photograph of the sectioned gross specimen (d) show gelatinous and myxoid consistency (*), septations (straight arrows), and the fibrous wall of the ganglion (curved arrows).
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Figure 7b. Nerve sheath ganglion in a 25-year-old man with peroneal nerve distribution symptoms. (a, b) Axial T1-weighted (600/20) (a) and fat-suppressed T2-weighted (4,666/90) (b) MR images show a fluid-appearing mass (arrowheads) adjacent to the anterolateral proximal fibula and peroneal nerve (arrow). (c, d) Intraoperative photograph (c) and photograph of the sectioned gross specimen (d) show gelatinous and myxoid consistency (*), septations (straight arrows), and the fibrous wall of the ganglion (curved arrows).
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Figure 7c. Nerve sheath ganglion in a 25-year-old man with peroneal nerve distribution symptoms. (a, b) Axial T1-weighted (600/20) (a) and fat-suppressed T2-weighted (4,666/90) (b) MR images show a fluid-appearing mass (arrowheads) adjacent to the anterolateral proximal fibula and peroneal nerve (arrow). (c, d) Intraoperative photograph (c) and photograph of the sectioned gross specimen (d) show gelatinous and myxoid consistency (*), septations (straight arrows), and the fibrous wall of the ganglion (curved arrows).
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Figure 7d. Nerve sheath ganglion in a 25-year-old man with peroneal nerve distribution symptoms. (a, b) Axial T1-weighted (600/20) (a) and fat-suppressed T2-weighted (4,666/90) (b) MR images show a fluid-appearing mass (arrowheads) adjacent to the anterolateral proximal fibula and peroneal nerve (arrow). (c, d) Intraoperative photograph (c) and photograph of the sectioned gross specimen (d) show gelatinous and myxoid consistency (*), septations (straight arrows), and the fibrous wall of the ganglion (curved arrows).
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Figure 8a. Peroneal nerve neurilemoma in a 49-year-old woman. (a-c) Coronal T1-weighted (435/40) (a) and axial T2-weighted (2,000/80) (b) MR images and longitudinal US scan (c) (photographically spliced together to show both ends of the lesion) reveal a well-defined fusiform mass (M) with entering and exiting nerve (*). Nerve appears central and within the capsule (large black arrowheads) of the mass, making distinction of neurilemoma from neurofibroma nearly impossible. MR images also reveal the surrounding fat (split-fat sign) (white arrowheads) and fascicular sign (small arrowheads in b). (d-f) Intraoperative photographs of lesion resection initially (d) reveal the fusiform mass (M) with entering and exiting peroneal nerve (*). Subsequently (e, f), incision of the epineurium (arrowheads) shows the lesion (curved arrow in e) separable from the nerve and resected with peroneal nerve fascicles left intact (straight arrows in f).
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Figure 8b. Peroneal nerve neurilemoma in a 49-year-old woman. (a-c) Coronal T1-weighted (435/40) (a) and axial T2-weighted (2,000/80) (b) MR images and longitudinal US scan (c) (photographically spliced together to show both ends of the lesion) reveal a well-defined fusiform mass (M) with entering and exiting nerve (*). Nerve appears central and within the capsule (large black arrowheads) of the mass, making distinction of neurilemoma from neurofibroma nearly impossible. MR images also reveal the surrounding fat (split-fat sign) (white arrowheads) and fascicular sign (small arrowheads in b). (d-f) Intraoperative photographs of lesion resection initially (d) reveal the fusiform mass (M) with entering and exiting peroneal nerve (*). Subsequently (e, f), incision of the epineurium (arrowheads) shows the lesion (curved arrow in e) separable from the nerve and resected with peroneal nerve fascicles left intact (straight arrows in f).
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Figure 8c. Peroneal nerve neurilemoma in a 49-year-old woman. (a-c) Coronal T1-weighted (435/40) (a) and axial T2-weighted (2,000/80) (b) MR images and longitudinal US scan (c) (photographically spliced together to show both ends of the lesion) reveal a well-defined fusiform mass (M) with entering and exiting nerve (*). Nerve appears central and within the capsule (large black arrowheads) of the mass, making distinction of neurilemoma from neurofibroma nearly impossible. MR images also reveal the surrounding fat (split-fat sign) (white arrowheads) and fascicular sign (small arrowheads in b). (d-f) Intraoperative photographs of lesion resection initially (d) reveal the fusiform mass (M) with entering and exiting peroneal nerve (*). Subsequently (e, f), incision of the epineurium (arrowheads) shows the lesion (curved arrow in e) separable from the nerve and resected with peroneal nerve fascicles left intact (straight arrows in f).
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Figure 8d. Peroneal nerve neurilemoma in a 49-year-old woman. (a-c) Coronal T1-weighted (435/40) (a) and axial T2-weighted (2,000/80) (b) MR images and longitudinal US scan (c) (photographically spliced together to show both ends of the lesion) reveal a well-defined fusiform mass (M) with entering and exiting nerve (*). Nerve appears central and within the capsule (large black arrowheads) of the mass, making distinction of neurilemoma from neurofibroma nearly impossible. MR images also reveal the surrounding fat (split-fat sign) (white arrowheads) and fascicular sign (small arrowheads in b). (d-f) Intraoperative photographs of lesion resection initially (d) reveal the fusiform mass (M) with entering and exiting peroneal nerve (*). Subsequently (e, f), incision of the epineurium (arrowheads) shows the lesion (curved arrow in e) separable from the nerve and resected with peroneal nerve fascicles left intact (straight arrows in f).
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Figure 8e. Peroneal nerve neurilemoma in a 49-year-old woman. (a-c) Coronal T1-weighted (435/40) (a) and axial T2-weighted (2,000/80) (b) MR images and longitudinal US scan (c) (photographically spliced together to show both ends of the lesion) reveal a well-defined fusiform mass (M) with entering and exiting nerve (*). Nerve appears central and within the capsule (large black arrowheads) of the mass, making distinction of neurilemoma from neurofibroma nearly impossible. MR images also reveal the surrounding fat (split-fat sign) (white arrowheads) and fascicular sign (small arrowheads in b). (d-f) Intraoperative photographs of lesion resection initially (d) reveal the fusiform mass (M) with entering and exiting peroneal nerve (*). Subsequently (e, f), incision of the epineurium (arrowheads) shows the lesion (curved arrow in e) separable from the nerve and resected with peroneal nerve fascicles left intact (straight arrows in f).
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Figure 8f. Peroneal nerve neurilemoma in a 49-year-old woman. (a-c) Coronal T1-weighted (435/40) (a) and axial T2-weighted (2,000/80) (b) MR images and longitudinal US scan (c) (photographically spliced together to show both ends of the lesion) reveal a well-defined fusiform mass (M) with entering and exiting nerve (*). Nerve appears central and within the capsule (large black arrowheads) of the mass, making distinction of neurilemoma from neurofibroma nearly impossible. MR images also reveal the surrounding fat (split-fat sign) (white arrowheads) and fascicular sign (small arrowheads in b). (d-f) Intraoperative photographs of lesion resection initially (d) reveal the fusiform mass (M) with entering and exiting peroneal nerve (*). Subsequently (e, f), incision of the epineurium (arrowheads) shows the lesion (curved arrow in e) separable from the nerve and resected with peroneal nerve fascicles left intact (straight arrows in f).
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Figure 9a. Tibial nerve neurilemoma in a 29-year-old man. (a) Lateral radiograph of the distal thigh shows a fusiform mass (*), exiting nerve (arrow), and surrounding fat (split-fat sign) (arrowheads). (b) Early arterial-phase angiogram reveals tortuous, corkscrew nutrient feeding vessels (curved arrows) at the superior aspect of the mass and the displaced superficial femoral artery (straight arrows).
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Figure 9b. Tibial nerve neurilemoma in a 29-year-old man. (a) Lateral radiograph of the distal thigh shows a fusiform mass (*), exiting nerve (arrow), and surrounding fat (split-fat sign) (arrowheads). (b) Early arterial-phase angiogram reveals tortuous, corkscrew nutrient feeding vessels (curved arrows) at the superior aspect of the mass and the displaced superficial femoral artery (straight arrows).
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Figure 10a. Sciatic nerve neurilemoma in a 24-year-old woman with radiating leg pain. (a) Axial T1-weighted (600/15) MR image shows the mass (*) with surrounding fat (arrows) adjacent to but separable from the sciatic nerve (arrowheads), which has a fascicular appearance, findings diagnostic of a neurilemoma. (b, c) Intraoperative photographs initially (b) reveal the lesion (solid black arrow) and entering nerve (white arrow) both within the epineurium. Nodular area represents intact sciatic nerve (open arrows). Subsequently (c), the sausage-shaped neurilemoma (*) is resected from the intact sciatic nerve (arrowhead) after incision of the epineurium (arrow).
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Figure 10b. Sciatic nerve neurilemoma in a 24-year-old woman with radiating leg pain. (a) Axial T1-weighted (600/15) MR image shows the mass (*) with surrounding fat (arrows) adjacent to but separable from the sciatic nerve (arrowheads), which has a fascicular appearance, findings diagnostic of a neurilemoma. (b, c) Intraoperative photographs initially (b) reveal the lesion (solid black arrow) and entering nerve (white arrow) both within the epineurium. Nodular area represents intact sciatic nerve (open arrows). Subsequently (c), the sausage-shaped neurilemoma (*) is resected from the intact sciatic nerve (arrowhead) after incision of the epineurium (arrow).
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Figure 10c. Sciatic nerve neurilemoma in a 24-year-old woman with radiating leg pain. (a) Axial T1-weighted (600/15) MR image shows the mass (*) with surrounding fat (arrows) adjacent to but separable from the sciatic nerve (arrowheads), which has a fascicular appearance, findings diagnostic of a neurilemoma. (b, c) Intraoperative photographs initially (b) reveal the lesion (solid black arrow) and entering nerve (white arrow) both within the epineurium. Nodular area represents intact sciatic nerve (open arrows). Subsequently (c), the sausage-shaped neurilemoma (*) is resected from the intact sciatic nerve (arrowhead) after incision of the epineurium (arrow).
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Figure 11a. Neurilemoma in a 35-year-old man with a palpable soft-tissue mass. (a) Coronal T1-weighted (500/20) MR image shows an elongated, low-signal-intensity mass (arrowheads). (b) On the axial T2-weighted (2,000/90) MR image, the mass has peripheral high signal intensity (white arrow) with low signal intensity centrally (black arrow), representing the target sign. No entering or exiting nerve is seen because the affected nerve is a small gastrocnemius intramuscular branch. (c, d) Photograph of the sectioned gross specimen (c) and photomicrograph (original magnification, x75; hematoxylin-eosin stain) (d) show corresponding more cellular Antoni A regions centrally (black *) and more myxoid Antoni B areas peripherally (white *) as well as a capsule (arrow in d).
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Figure 11b. Neurilemoma in a 35-year-old man with a palpable soft-tissue mass. (a) Coronal T1-weighted (500/20) MR image shows an elongated, low-signal-intensity mass (arrowheads). (b) On the axial T2-weighted (2,000/90) MR image, the mass has peripheral high signal intensity (white arrow) with low signal intensity centrally (black arrow), representing the target sign. No entering or exiting nerve is seen because the affected nerve is a small gastrocnemius intramuscular branch. (c, d) Photograph of the sectioned gross specimen (c) and photomicrograph (original magnification, x75; hematoxylin-eosin stain) (d) show corresponding more cellular Antoni A regions centrally (black *) and more myxoid Antoni B areas peripherally (white *) as well as a capsule (arrow in d).
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Figure 11c. Neurilemoma in a 35-year-old man with a palpable soft-tissue mass. (a) Coronal T1-weighted (500/20) MR image shows an elongated, low-signal-intensity mass (arrowheads). (b) On the axial T2-weighted (2,000/90) MR image, the mass has peripheral high signal intensity (white arrow) with low signal intensity centrally (black arrow), representing the target sign. No entering or exiting nerve is seen because the affected nerve is a small gastrocnemius intramuscular branch. (c, d) Photograph of the sectioned gross specimen (c) and photomicrograph (original magnification, x75; hematoxylin-eosin stain) (d) show corresponding more cellular Antoni A regions centrally (black *) and more myxoid Antoni B areas peripherally (white *) as well as a capsule (arrow in d).
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Figure 11d. Neurilemoma in a 35-year-old man with a palpable soft-tissue mass. (a) Coronal T1-weighted (500/20) MR image shows an elongated, low-signal-intensity mass (arrowheads). (b) On the axial T2-weighted (2,000/90) MR image, the mass has peripheral high signal intensity (white arrow) with low signal intensity centrally (black arrow), representing the target sign. No entering or exiting nerve is seen because the affected nerve is a small gastrocnemius intramuscular branch. (c, d) Photograph of the sectioned gross specimen (c) and photomicrograph (original magnification, x75; hematoxylin-eosin stain) (d) show corresponding more cellular Antoni A regions centrally (black *) and more myxoid Antoni B areas peripherally (white *) as well as a capsule (arrow in d).
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Figure 12a. Tibial nerve neurofibroma in a 30-year-old man. (a) Axial CT scan shows a low-attenuation well-defined mass (arrow) with a center of slightly increased attenuation (white arrowheads) and incomplete fat rim (black arrowheads) (target sign). (b, c) Sagittal T1-weighted (500/17) (b) and axial T2-weighted (2,000/80) (c) MR images reveal entering nerve (open arrow in b), partial fat rim (split-fat sign), and capsule (solid arrow in b) and high-signal-intensity peripheral rim (target sign) (arrowheads in c). (d) Photograph of the axially sectioned gross specimen from debulking surgery shows the capsule (white arrows), peripheral myxoid region (black arrows), and central more solid tissue (*).
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Figure 12b. Tibial nerve neurofibroma in a 30-year-old man. (a) Axial CT scan shows a low-attenuation well-defined mass (arrow) with a center of slightly increased attenuation (white arrowheads) and incomplete fat rim (black arrowheads) (target sign). (b, c) Sagittal T1-weighted (500/17) (b) and axial T2-weighted (2,000/80) (c) MR images reveal entering nerve (open arrow in b), partial fat rim (split-fat sign), and capsule (solid arrow in b) and high-signal-intensity peripheral rim (target sign) (arrowheads in c). (d) Photograph of the axially sectioned gross specimen from debulking surgery shows the capsule (white arrows), peripheral myxoid region (black arrows), and central more solid tissue (*).
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Figure 12c. Tibial nerve neurofibroma in a 30-year-old man. (a) Axial CT scan shows a low-attenuation well-defined mass (arrow) with a center of slightly increased attenuation (white arrowheads) and incomplete fat rim (black arrowheads) (target sign). (b, c) Sagittal T1-weighted (500/17) (b) and axial T2-weighted (2,000/80) (c) MR images reveal entering nerve (open arrow in b), partial fat rim (split-fat sign), and capsule (solid arrow in b) and high-signal-intensity peripheral rim (target sign) (arrowheads in c). (d) Photograph of the axially sectioned gross specimen from debulking surgery shows the capsule (white arrows), peripheral myxoid region (black arrows), and central more solid tissue (*).
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Figure 12d. Tibial nerve neurofibroma in a 30-year-old man. (a) Axial CT scan shows a low-attenuation well-defined mass (arrow) with a center of slightly increased attenuation (white arrowheads) and incomplete fat rim (black arrowheads) (target sign). (b, c) Sagittal T1-weighted (500/17) (b) and axial T2-weighted (2,000/80) (c) MR images reveal entering nerve (open arrow in b), partial fat rim (split-fat sign), and capsule (solid arrow in b) and high-signal-intensity peripheral rim (target sign) (arrowheads in c). (d) Photograph of the axially sectioned gross specimen from debulking surgery shows the capsule (white arrows), peripheral myxoid region (black arrows), and central more solid tissue (*).
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Figure 13a. Spinal neurofibroma in a 31-year-old woman. (a) Coronal T1-weighted (500/15) MR image shows a paraspinal mass (*) with entering nerve in the neural foramen (arrowhead). (b) Intraoperative photograph reveals the paraspinal mass (arrow) and entering nerve (arrowhead).
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Figure 13b. Spinal neurofibroma in a 31-year-old woman. (a) Coronal T1-weighted (500/15) MR image shows a paraspinal mass (*) with entering nerve in the neural foramen (arrowhead). (b) Intraoperative photograph reveals the paraspinal mass (arrow) and entering nerve (arrowhead).
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Figure 14a. Diffuse neurofibroma in a 31-year-old woman without neurofibromatosis. (a, b) Coronal T1-weighted (600/20) (a) and T2-weighted (2,500/80) (b) MR images show an infiltrative mass extending along connective tissue septa (arrowheads in a) involving the left buttock. On the T2-weighted image (b), the mass has prominent low signal intensity (*). (c) Photograph of the gross specimen reveals the infiltrative characteristics of the mass (*) within the subcutaneous tissue. Scale is in centimeters.
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Figure 14b. Diffuse neurofibroma in a 31-year-old woman without neurofibromatosis. (a, b) Coronal T1-weighted (600/20) (a) and T2-weighted (2,500/80) (b) MR images show an infiltrative mass extending along connective tissue septa (arrowheads in a) involving the left buttock. On the T2-weighted image (b), the mass has prominent low signal intensity (*). (c) Photograph of the gross specimen reveals the infiltrative characteristics of the mass (*) within the subcutaneous tissue. Scale is in centimeters.
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Figure 14c. Diffuse neurofibroma in a 31-year-old woman without neurofibromatosis. (a, b) Coronal T1-weighted (600/20) (a) and T2-weighted (2,500/80) (b) MR images show an infiltrative mass extending along connective tissue septa (arrowheads in a) involving the left buttock. On the T2-weighted image (b), the mass has prominent low signal intensity (*). (c) Photograph of the gross specimen reveals the infiltrative characteristics of the mass (*) within the subcutaneous tissue. Scale is in centimeters.
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Figure 15a. NF1 with ribbon ribs resulting from multiple plexiform neurofibromas in a 20-year-old man. (a) Chest radiograph shows multilobulated extrapleural masses (arrowheads) and scalloping of all ribs with a ribbonlike appearance. (b) Photograph of the autopsy gross specimen reveals that the rib abnormalities resulted from multiple neurofibromas of intercostal nerves (*) arising from the spinal cord (arrows).
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Figure 15b. NF1 with ribbon ribs resulting from multiple plexiform neurofibromas in a 20-year-old man. (a) Chest radiograph shows multilobulated extrapleural masses (arrowheads) and scalloping of all ribs with a ribbonlike appearance. (b) Photograph of the autopsy gross specimen reveals that the rib abnormalities resulted from multiple neurofibromas of intercostal nerves (*) arising from the spinal cord (arrows).
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Figure 16a. Plexiform neurofibromas about the elbow and distal thigh in a 21-year-old woman with NF1. (a) CT scan of the mid-thigh level shows multiple low-attenuation plexiform neurofibromas (arrowheads), several of which show a central area of higher attenuation (arrows), representing the target sign. (b, c) Sagittal T1-weighted (800/20) (b) MR image of the elbow and axial T2-weighted (2,000/90) (c) MR image of the lower thigh reveal convoluted multinodular masses and thickening (arrowheads) from plexiform neurofibromas and numerous areas of target sign on the T2-weighted image (arrows in c). (d, e) Intraoperative photographs of the distal thigh initially (d) show the bag-of-worm (arrows) appearance of serpentine plexiform neurofibromas. Subsequent incision (e) of the distal sciatic nerve epineurium (arrowhead) reveals markedly thickened nerve branches (*).
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Figure 16b. Plexiform neurofibromas about the elbow and distal thigh in a 21-year-old woman with NF1. (a) CT scan of the mid-thigh level shows multiple low-attenuation plexiform neurofibromas (arrowheads), several of which show a central area of higher attenuation (arrows), representing the target sign. (b, c) Sagittal T1-weighted (800/20) (b) MR image of the elbow and axial T2-weighted (2,000/90) (c) MR image of the lower thigh reveal convoluted multinodular masses and thickening (arrowheads) from plexiform neurofibromas and numerous areas of target sign on the T2-weighted image (arrows in c). (d, e) Intraoperative photographs of the distal thigh initially (d) show the bag-of-worm (arrows) appearance of serpentine plexiform neurofibromas. Subsequent incision (e) of the distal sciatic nerve epineurium (arrowhead) reveals markedly thickened nerve branches (*).
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Figure 16c. Plexiform neurofibromas about the elbow and distal thigh in a 21-year-old woman with NF1. (a) CT scan of the mid-thigh level shows multiple low-attenuation plexiform neurofibromas (arrowheads), several of which show a central area of higher attenuation (arrows), representing the target sign. (b, c) Sagittal T1-weighted (800/20) (b) MR image of the elbow and axial T2-weighted (2,000/90) (c) MR image of the lower thigh reveal convoluted multinodular masses and thickening (arrowheads) from plexiform neurofibromas and numerous areas of target sign on the T2-weighted image (arrows in c). (d, e) Intraoperative photographs of the distal thigh initially (d) show the bag-of-worm (arrows) appearance of serpentine plexiform neurofibromas. Subsequent incision (e) of the distal sciatic nerve epineurium (arrowhead) reveals markedly thickened nerve branches (*).
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Figure 16d. Plexiform neurofibromas about the elbow and distal thigh in a 21-year-old woman with NF1. (a) CT scan of the mid-thigh level shows multiple low-attenuation plexiform neurofibromas (arrowheads), several of which show a central area of higher attenuation (arrows), representing the target sign. (b, c) Sagittal T1-weighted (800/20) (b) MR image of the elbow and axial T2-weighted (2,000/90) (c) MR image of the lower thigh reveal convoluted multinodular masses and thickening (arrowheads) from plexiform neurofibromas and numerous areas of target sign on the T2-weighted image (arrows in c). (d, e) Intraoperative photographs of the distal thigh initially (d) show the bag-of-worm (arrows) appearance of serpentine plexiform neurofibromas. Subsequent incision (e) of the distal sciatic nerve epineurium (arrowhead) reveals markedly thickened nerve branches (*).
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Figure 16e. Plexiform neurofibromas about the elbow and distal thigh in a 21-year-old woman with NF1. (a) CT scan of the mid-thigh level shows multiple low-attenuation plexiform neurofibromas (arrowheads), several of which show a central area of higher attenuation (arrows), representing the target sign. (b, c) Sagittal T1-weighted (800/20) (b) MR image of the elbow and axial T2-weighted (2,000/90) (c) MR image of the lower thigh reveal convoluted multinodular masses and thickening (arrowheads) from plexiform neurofibromas and numerous areas of target sign on the T2-weighted image (arrows in c). (d, e) Intraoperative photographs of the distal thigh initially (d) show the bag-of-worm (arrows) appearance of serpentine plexiform neurofibromas. Subsequent incision (e) of the distal sciatic nerve epineurium (arrowhead) reveals markedly thickened nerve branches (*).
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Figure 17a. Elephantiasis neuromatosa of the upper extremity in a 29-year-old woman with NF1. (a, b) Forearm radiograph (a) and photograph of the amputation specimen (b) show massive enlargement of the upper extremity with dysplastic changes of the radius and ulna, including dislocation (arrowhead). (c) Intraoperative photograph of the axillary dissection shows extensive plexiform neurofibromas with bag-of-worms appearance caused by multinodular thickening (*) of all nerves and their branches.
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Figure 17b. Elephantiasis neuromatosa of the upper extremity in a 29-year-old woman with NF1. (a, b) Forearm radiograph (a) and photograph of the amputation specimen (b) show massive enlargement of the upper extremity with dysplastic changes of the radius and ulna, including dislocation (arrowhead). (c) Intraoperative photograph of the axillary dissection shows extensive plexiform neurofibromas with bag-of-worms appearance caused by multinodular thickening (*) of all nerves and their branches.
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Figure 17c. Elephantiasis neuromatosa of the upper extremity in a 29-year-old woman with NF1. (a, b) Forearm radiograph (a) and photograph of the amputation specimen (b) show massive enlargement of the upper extremity with dysplastic changes of the radius and ulna, including dislocation (arrowhead). (c) Intraoperative photograph of the axillary dissection shows extensive plexiform neurofibromas with bag-of-worms appearance caused by multinodular thickening (*) of all nerves and their branches.
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Figure 18. Bilateral spinal neurogenic neoplasms in a 21-year-old man with NF1. CT scan shows bilateral paraspinal masses (*) with nerves entering from the neural foramina (arrowheads). The larger low-attenuation mass on the left is a malignant PNST, whereas the smaller right-sided lesion is a neurofibroma.
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Figure 19a. Malignant PNST in a 42-year-old man with NF1 and rapid enlargement of a mid-thigh neurofibroma resulting from malignant transformation. (a, b) Coronal T1-weighted (634/18) (a) and inversion recovery (3,000/60; inversion time, 160 msec) (b) MR images show a thickened sciatic nerve entering and exiting (straight solid arrows in a) a focal heterogeneous mass with a rim of fat (split-fat sign) (curved arrow). A central area of necrosis (*) has high signal intensity on the inversion recovery image, as does the tumor extension along the entering nerve proximally and exiting nerve distally (arrowheads in b) and a second subcutaneous neurofibroma (open arrow in b). (c) Axial fat-suppressed contrast-enhanced T1-weighted MR image shows the mass with ill-defined margins (white arrows), resulting from invasion of surrounding tissues, and nodular peripheral enhancement (black arrows) with lack of contrast (*) in a necrotic center. (d) Photograph of the gross specimen shows multinodular thickening of a plexiform neurofibroma of both the sciatic nerve and its branches (solid arrows) and a necrotic center in the malignant PNST (open arrow).
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Figure 19b. Malignant PNST in a 42-year-old man with NF1 and rapid enlargement of a mid-thigh neurofibroma resulting from malignant transformation. (a, b) Coronal T1-weighted (634/18) (a) and inversion recovery (3,000/60; inversion time, 160 msec) (b) MR images show a thickened sciatic nerve entering and exiting (straight solid arrows in a) a focal heterogeneous mass with a rim of fat (split-fat sign) (curved arrow). A central area of necrosis (*) has high signal intensity on the inversion recovery image, as does the tumor extension along the entering nerve proximally and exiting nerve distally (arrowheads in b) and a second subcutaneous neurofibroma (open arrow in b). (c) Axial fat-suppressed contrast-enhanced T1-weighted MR image shows the mass with ill-defined margins (white arrows), resulting from invasion of surrounding tissues, and nodular peripheral enhancement (black arrows) with lack of contrast (*) in a necrotic center. (d) Photograph of the gross specimen shows multinodular thickening of a plexiform neurofibroma of both the sciatic nerve and its branches (solid arrows) and a necrotic center in the malignant PNST (open arrow).
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Figure 19c. Malignant PNST in a 42-year-old man with NF1 and rapid enlargement of a mid-thigh neurofibroma resulting from malignant transformation. (a, b) Coronal T1-weighted (634/18) (a) and inversion recovery (3,000/60; inversion time, 160 msec) (b) MR images show a thickened sciatic nerve entering and exiting (straight solid arrows in a) a focal heterogeneous mass with a rim of fat (split-fat sign) (curved arrow). A central area of necrosis (*) has high signal intensity on the inversion recovery image, as does the tumor extension along the entering nerve proximally and exiting nerve distally (arrowheads in b) and a second subcutaneous neurofibroma (open arrow in b). (c) Axial fat-suppressed contrast-enhanced T1-weighted MR image shows the mass with ill-defined margins (white arrows), resulting from invasion of surrounding tissues, and nodular peripheral enhancement (black arrows) with lack of contrast (*) in a necrotic center. (d) Photograph of the gross specimen shows multinodular thickening of a plexiform neurofibroma of both the sciatic nerve and its branches (solid arrows) and a necrotic center in the malignant PNST (open arrow).
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Figure 19d. Malignant PNST in a 42-year-old man with NF1 and rapid enlargement of a mid-thigh neurofibroma resulting from malignant transformation. (a, b) Coronal T1-weighted (634/18) (a) and inversion recovery (3,000/60; inversion time, 160 msec) (b) MR images show a thickened sciatic nerve entering and exiting (straight solid arrows in a) a focal heterogeneous mass with a rim of fat (split-fat sign) (curved arrow). A central area of necrosis (*) has high signal intensity on the inversion recovery image, as does the tumor extension along the entering nerve proximally and exiting nerve distally (arrowheads in b) and a second subcutaneous neurofibroma (open arrow in b). (c) Axial fat-suppressed contrast-enhanced T1-weighted MR image shows the mass with ill-defined margins (white arrows), resulting from invasion of surrounding tissues, and nodular peripheral enhancement (black arrows) with lack of contrast (*) in a necrotic center. (d) Photograph of the gross specimen shows multinodular thickening of a plexiform neurofibroma of both the sciatic nerve and its branches (solid arrows) and a necrotic center in the malignant PNST (open arrow).
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Figure 20. Malignant PNST in the thigh of a 22-year-old man with NF1. Gallium-67 scintiscan obtained 5 days after injection shows intense uptake of radionuclide in the malignant PNST (*) but no accumulation in multiple other neurofibromas that were clinically evident.
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Figure 21a. Malignant PNST of the sciatic nerve in a 12-year-old girl. (a) Axial T2-weighted (2,000/90) MR image shows a mass (black arrowheads) posterior to the acetabulum with the fascicular sign (white arrowheads) and decreased size of gluteal muscles from atrophy (arrows). (b) Photograph of the sectioned gross specimen reveals fascicular morphology (*) of the malignant PNST, corresponding to the MR imaging appearance.
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Figure 21b. Malignant PNST of the sciatic nerve in a 12-year-old girl. (a) Axial T2-weighted (2,000/90) MR image shows a mass (black arrowheads) posterior to the acetabulum with the fascicular sign (white arrowheads) and decreased size of gluteal muscles from atrophy (arrows). (b) Photograph of the sectioned gross specimen reveals fascicular morphology (*) of the malignant PNST, corresponding to the MR imaging appearance.
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