(Radiographics. 1999;19:817-819.)
© RSNA, 1999
US Case of the Day1
Ashley F. Ceola, MD and
Teresita L. Angtuaco, MD
1 From the Department of Radiology, University of Arkansas for Medical Sciences, Slot 581, 4301 W Markham, Little Rock, AR 72205. From the 1998 RSNA scientific assembly. Received November 20, 1998; revision requested December 30 and received February 3, 1999; accepted February 4. Address reprint requests to T.L.A.
Index Terms: Fetus, abnormalities, 791.1459, 856.8759 • Fetus, growth and development, 791.1459, 856.8759 • Lung, abnormalities, 60.1452, 791.1459, 856.8759
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HISTORY
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A 15-year-old primigravida girl was referred to our hospital for a second opinion because a suspected mass had been seen in the fetal abdomen at prenatal ultrasound (US) performed at the obstetrician's office. The obstetrician had estimated the gestational age of the fetus at 24 weeks on the basis of US examination results. Conventional and color Doppler US were performed. Repeat US was performed at subsequent prenatal visits. Neonatal US and magnetic resonance (MR) imaging were also performed.
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FINDINGS
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Conventional US showed a fetus with appropriate growth at 28 weeks gestation. An echogenic mass was seen in the left upper quadrant just below the diaphragm. The mass had an echolucent center and appeared separate from the left kidney; however, a definite plane of separation could not be defined (Fig 1). Subsequent color Doppler US of the kidneys showed the mass to be relatively avascular and not supplied by the renal vessels (Fig 2). Repeat US performed at follow-up showed a clear separation between the mass and the left kidney, suggesting that the mass could be arising from the adrenal gland (Fig 3). The fetus demonstrated appropriate growth at subsequent prenatal visits, and the mass did not change in size or characteristics throughout the remainder of the pregnancy. Neonatal US revealed a mass with mixed echogenicity superior to the left adrenal gland (Fig 4a). Several cystic areas were seen within the predominantly solid portion of the mass. The left adrenal gland and left kidney were both displaced inferiorly by the mass (Fig 4b). Magnetic resonance (MR) imaging revealed that the mass was adjacent to the aorta but did not displace it. The mass had low signal intensity on T1-weighted MR images (Fig 5a) and high signal intensity on T2-weighted images (Fig 5b).
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Figure 1a. (a) Axial US image of the fetal abdomen shows the fetus in breech presentation with its spine toward the mother's left side (arrow). A left paraspinal mass (arrowhead) appears predominantly solid but also demonstrates several cystic areas. (b) Longitudinal US image of the fetal chest and abdomen demonstrates that the mass is subdiaphragmatic in location but is not clearly differentiated from the surrounding organs.
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Figure 1b. (a) Axial US image of the fetal abdomen shows the fetus in breech presentation with its spine toward the mother's left side (arrow). A left paraspinal mass (arrowhead) appears predominantly solid but also demonstrates several cystic areas. (b) Longitudinal US image of the fetal chest and abdomen demonstrates that the mass is subdiaphragmatic in location but is not clearly differentiated from the surrounding organs.
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Figure 2. Color Doppler US image of the fetal abdomen clearly demonstrates the aorta and renal vessels (arrow). The mass does not appear to be vascular but does appear to be separate from the kidney (arrowhead).
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Figure 4a. (a) Longitudinal US image of the left upper quadrant of the neonatal abdomen shows the mass (arrow) separate from the adrenal gland (arrowhead). (b) Coronal US image of the neonatal abdomen obtained just inferior to a shows the relationship between the aorta, mass, adrenal gland, and left kidney (arrow).
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Figure 4b. (a) Longitudinal US image of the left upper quadrant of the neonatal abdomen shows the mass (arrow) separate from the adrenal gland (arrowhead). (b) Coronal US image of the neonatal abdomen obtained just inferior to a shows the relationship between the aorta, mass, adrenal gland, and left kidney (arrow).
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Figure 5a. (a) On a coronal T1-weighted MR image of the chest and abdomen, the mass has low signal intensity with high-signal-intensity cystic areas corresponding to those seen at prenatal US, a finding that suggests the presence of hemorrhage. Both adrenal glands are visualized (arrows), with the left adrenal gland being displaced inferiorly by the mass. (b) On an axial T2-weighted MR image of the abdomen, the mass is markedly hyperintense relative to the adrenal glands (arrows).
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Figure 5b. (a) On a coronal T1-weighted MR image of the chest and abdomen, the mass has low signal intensity with high-signal-intensity cystic areas corresponding to those seen at prenatal US, a finding that suggests the presence of hemorrhage. Both adrenal glands are visualized (arrows), with the left adrenal gland being displaced inferiorly by the mass. (b) On an axial T2-weighted MR image of the abdomen, the mass is markedly hyperintense relative to the adrenal glands (arrows).
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DIAGNOSIS: Extralobar pulmonary sequestration.
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DISCUSSION
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Fetal masses within the left upper quadrant are unusual and may indicate abnormalities of the spleen, left kidney, left adrenal gland, and pancreas as well as sequestration. Initial US revealed a normal-appearing fetal spleen but was unable to demonstrate the mass as separate from the kidney. Renal masses in the fetus include congenital polycystic kidneys, multicystic dysplastic kidneys, mesoblastic nephroma, and Wilms tumor. Renal tumors will demonstrate a paraspinal component that was not seen in this case. In addition, the kidney had a normal morphologic appearance. Follow-up US revealed the mass to be separate from the kidney and possibly arising from the adrenal gland. The most common adrenal mass in the neonate is either adrenal hemorrhage or fetal adrenal neuroblastoma. Adrenal hemorrhage rarely manifests in utero and will demonstrate changing characteristics on sequential images as it evolves. Neuroblastoma and sequestration will demonstrate more stable characteristics. Neuroblastoma can also demonstrate multiple cystic components similar to those seen in this case. Other adrenal diagnostic considerations include congenital adrenal cyst and, in the neonate, adrenal abscess (1).
Pulmonary sequestration is a congenital anomaly of the primitive foregut and is defined as a mass of nonfunctioning lung parenchyma with no connection to the tracheobronchial tree. Intralobar sequestrations are found within the normal lung tissue and share its visceral pleura, whereas extralobar sequestrations are outside the normal lung parenchyma and are enclosed in their own visceral pleura (2). Of the two varieties, extralobar sequestration is less common and comprises 25% of all sequestrations (3). Extralobar sequestrations are predominantly found on the left side and are usually related to the left hemidiaphragm. They are generally located between the left lower lobe and the diaphragm but may also be pericardial, interdiaphragmatic, mediastinal, or retroperitoneal in location (4). Only 10% of extralobar sequestrations are subdiaphragmatic (3). They are supplied by the systemic arterial system in 95% of cases and are usually aortic. Venous drainage can be to the pulmonary veins, typically a branch of the inferior pulmonary vein, which can cause a left-to-left shunt. Other sources of drainage include the inferior vena cava and the azygous system (2).
Presenting signs and symptoms of extralobar sequestration in the neonate include respiratory distress, cyanosis, feeding disorders, and failure to thrive. These masses are usually discovered as abdominal masses during early childhood, usually within the first 2 years of life. Although the masses are usually asymptomatic, they have been associated with large pleural effusions (5). The anomalous circulation can cause a notable left-to-left shunt and, if within the thorax, compression of normal lung. Only 10% of cases remain asymptomatic into adulthood (4).
Congenital anomalies are more frequent with extralobar sequestrations than with intralobar sequestrations, occurring in up to 65% of cases (4). The most common associated anomalies are diaphragmatic hernias. Other associated anomalies include bronchial agenesis, colonic duplication, and vertebral anomalies (5).
Evaluation of sequestrations can be accomplished with many different imaging modalities (6). Sequestrations occurring within the thorax or adjacent to the diaphragm can be demonstrated at chest radiography and tend to appear as well-demarcated, mostly homogeneous areas of increased opacity (7). Pulmonary angiography can show anomalous arterial and venous connections of the lesion, which are diagnostic. Less invasive imaging techniques such as US, computed tomography, and MR imaging or MR angiography are also helpful. Treatment consists of surgical excision with careful ligation of the arterial supply. Morbidity and mortality are usually associated with concomitant congenital anomalies, none of which was seen in this case.
The neonate underwent surgery and had an uneventful recovery.
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References
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Fenton LZ, Williams JL. Bronchopulmonary foregut malformation mimicking neuroblastoma. Pediatr Radiol 1996; 26:729-730.[Medline]
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Avishai V, Dolev E, Wiessberg D, Zajdel L, Priel IE. Extralobar sequestration presenting as massive hemothorax. Chest 1996; 109:843-845.[Abstract/Free Full Text]
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Louie HW, Martin SM, Mulder DG. Pulmonary sequestration: 17-year experience at UCLA. Am Surg 1993; 59:801-805.[Medline]
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Sippel JM, Ravichandran PS, Antonovic R, Holden WE. Extralobar pulmonary sequestration presenting as a mediastinal malignancy. Ann Thoracic Surg 1997; 63:1169-1171.[Abstract/Free Full Text]
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Kitterman JA. Parenchymal lesions. In: Rudolph AM, Hoffman JIE, Rudolph CD, eds. Rudolph's pediatrics. Stamford, Conn: Appleton & Lange, 1996; 1587-1588.
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Hang JD, Guo QY, Chen CX, Chen LY. Imaging approach to the diagnosis of pulmonary sequestration. Acta Radiologica 1996; 37:883-888.[Medline]
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Tsolakis CC, Kollias VD, Panayotopoulos PP. Pulmonary sequestration: experience with eight consecutive cases. Scand Cardiovasc J 1997; 31:229-232.[Medline]
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HISTORY
FINDINGS
