(Radiographics. 1999;19:252-254.)
© RSNA, 1999
General Case of the Day
Deepak Takhtani, MD1,
Samy F. Saleeb, MD1 and
Steven K. Teplick, MD1
1 Department of Radiology, University of South Alabama College of Medicine, 2451 Fillingim St, Mobile, AL 36617.
Index Terms: Abdomen, CT, 70.1211, 80.1211 • Abdomen, neoplasms, 80.329 • Omentum, neoplasms, 791.33, 792.329 • Scrotum, neoplasms, 847.33
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HISTORY
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A 28-year-old man presented with complaints of gradually increasing abdominal swelling and discomfort over a 1-month period. The patient also noted swelling of the right leg and scrotum. Physical examination revealed diffuse abdominal swelling suspicious for ascites. Multiple nodules were palpated on the right side of the scrotum. Ultrasound (US) of the abdomen and scrotum and computed tomography (CT) of the abdomen were performed. Histologic specimens were obtained with US-guided core biopsy of the abdominal mass and open biopsy of a testicular nodule.
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FINDINGS
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Abdominal US showed a large mass with mixed echogenicity in the midabdomen (Fig 1). Several nodules were seen attached to the scrotal wall on the right side of the scrotum (Fig 2). A small hydrocele was also noted. Subsequent CT of the abdomen showed several large masses in the abdomen and pelvis, along with ascites. The largest mass arising from the omentum was composed of both solid and necrotic components (Figs 3, 4). Tumor foci were also seen in the paracolic gutters and rectovesical pouch. CT scans obtained later showed a gradual increase in tumor necrosis, further seeding along the peritoneal surface, and liver metastases.
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Figure 1. Figures 1,2. (1) US image of the right lumbar region demonstrates a large, lobulated mass with mixed echogenicity (m) as well as ascites. (2) US image of the scrotum shows two nodules (n) attached to the scrotal wall, along with a small hydrocele. e = epididymis, t = right testis.
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Figure 2. Figures 1,2. (1) US image of the right lumbar region demonstrates a large, lobulated mass with mixed echogenicity (m) as well as ascites. (2) US image of the scrotum shows two nodules (n) attached to the scrotal wall, along with a small hydrocele. e = epididymis, t = right testis.
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Figure 3. Figures 3, 4. (3) CT scan of the abdomen demonstrates a large omental mass (m) and ascites. (4) CT scan of the pelvis show a mass (m) in the rectovesical space compressing the rectum posteriorly (arrowhead).
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Figure 4. Figures 3, 4. (3) CT scan of the abdomen demonstrates a large omental mass (m) and ascites. (4) CT scan of the pelvis show a mass (m) in the rectovesical space compressing the rectum posteriorly (arrowhead).
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DIAGNOSIS: Desmoplastic small round cell tumor of the abdomen with scrotal metastases.
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DISCUSSION
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Desmoplastic small round cell tumor is a highly malignant tumor belonging to a generic group of small round blue cell tumors seen in children and young adults. This group includes tumors such as Ewing sarcoma, neuroblastoma, Wilms tumor, rhabdomyosarcoma, and primitive neuroendocrine tumor (1). Desmoplastic small round cell tumor is a distinct entity with well-recognized histologic features, karyotype, and immunochemical characteristics. The cell of origin may be from mesothelial, submesothelial, or subserosal mesenchyme of the abdominal cavity. Immunoreactivity indicates a blastomatous cell of origin with a polyphenotypic appearance. At histologic analysis, the tumor manifests as islands of small blue cells surrounded by fibrous stroma (Fig 5). In this case, immunohistochemical analysis revealed the presence of cytoplasmic keratin and desmin, a finding that fits well with a diagnosis of desmoplastic small round cell tumor. Chromosomal studies have demonstrated abnormality of chromosome 11, which is typical, although nonspecific, for this lesion (1). Chromosomal abnormality t(11;22)(p13;q12) has been reported more frequently (1).
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Figure 5. Low-power photomicrograph (original magnification, x10; hematoxylin-eosin stain) demonstrates desmoplastic stroma separating multiple nests of undifferentiated small, monotonous tumor cells.
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Desmoplastic small round cell tumor was first described by Gerald and Rosai in 1991 (2). Since then, more than 100 cases have been reported in the literature. This tumor usually affects children and young adults with a median age at presentation of 21 years (2). There is a significant (4:1) male predilection. Most patients present with gastrointestinal or genitourinary discomfort because these tumors usually arise in the abdomen or pelvis. The majority of tumors are in close proximity to the mesentery with direct or metastatic spread to the omentum (Fig 3). Other sites of origin include the retroperitoneum, posterior mediastinum, and meninges (3). Pleural origin of desmoplastic small round cell tumor with close resemblance to mesothelioma has been reported (4). A recent article described six cases of paratesticular origin of desmoplastic small round cell tumor (5). Our case is unusual owing to the synchronous presence of multiple abdominal masses and scrotal nodules (Figs 1, 2). Scrotal nodules may represent metastatic deposits from direct spread; however, it has also been postulated that paratesticular involvement may represent primary growth within additional serosa at risk, rather than seeding, because most cases occur in young adults or adolescents in whom the vaginal process of the peritoneum has long since closed. Metastatic spread is common and may occur via the lymph nodes or bloodstream as well as via direct implantation along the serosal coverings.
In desmoplastic small round cell tumor, cross-sectional imaging shows multiple, scattered necrotic tumor masses in the abdomen and pelvis (Figs 3, 4) (6). No organ preference has been described. Diffuse metastatic deposits on the peritoneal surfaces and omentum from any primary malignancy may mimic desmoplastic small round cell tumor at imaging. Carcinoma of the colon, stomach, ovary, or pancreas as well as melanoma, leiomyosarcoma, rhabdomyosarcoma and lymphoma may manifest as widespread abdominal nodules resembling desmoplastic small round cell tumor. Close scrutiny for any dominant, organ-specific mass may help differentiate other processes from desmoplastic small round cell tumor. One may also face a dilemma in differentiating desmoplastic small round cell tumor from diffusely spreading entities such as desmoid tumor, mesothelioma, tumefactive tuberculosis, actinomycosis, and Castleman disease.
Laboratory test results are noncontributory and tumor markers are normal, although lactic dehydrogenase levels may be elevated in some cases (3). Patients with desmoplastic small round cell tumor have a poor prognosis with a mean survival time of 17 months. Most patients are treated with combination chemotherapy with only partial success (3).
A diagnosis of desmoplastic small round cell tumor should be suspected if a child or young adult male presents with multiple abdominal or pelvic masses attached to the peritoneal surface with no definite visceral organ of origin.
The two biopsy procedures performed in our case yielded identical histologic findings. The patient received four courses of combination chemotherapy consisting of adriamycin 5-fluorouracil and cyclophosphamide, which slowed progression of the tumor; however, there was no substantive decrease in the size or number of tumor foci. Debulking surgery was performed nearly 6 months after initial presentation. Surgery was limited by extensive multifocal tumor masses in the peritoneum and along the sigmoid colon, jejunum, pelvis, liver surface, and retroperitoneum. The patient often had symptoms of intestinal obstruction for which he was treated conservatively. His condition continued to deteriorate, and he died 1 year after initial presentation.
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Footnotes
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Address reprint requests to S.F.S.
From the 1998 RSNA scientific assembly.
Received for publication August 28, 1998.
Revision received September 23, 1998. October 22, 1998.
Accepted for publication October 22, 1998.
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References
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Amato RJ, Ellerhorst JA, Ayala AG. Intraabdominal desmoplastic small cell tumor: report and discussion of five cases. Cancer 1996; 78:845-851.[Medline]
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Gerald WL, Rosai J. Desmoplastic small cell tumor with divergent differentiation. Pediatr Pathol 1989; 9:177-183.[Medline]
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Kretschmar CS, Colbach C, Bhan I, Crombleholme M. Desmoplastic small cell tumor: a report of three cases and a review of literature. J Pediatr Oncol 1996; 18:293-298.
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Parkash V, Gerald WL, Parma A, Miettinen M, Rosai J. Desmoplastic small round cell tumor of the pleura. Am J Surg Pathol 1995; 19:659-665.[Medline]
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Cummings OW, Ulbright TM, Young RH, Del Tos AP, Fletcher CD, Hull MT. Desmoplastic small round cell tumors of the paratesticular region: a report of six cases. Am J Surg Pathol 1997; 21:219-225.[Medline]
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Dao Huhh-Ninh V, Dachman AH. CT findings of regression in intraabdominal desmoplastic small cell tumor. Clin Imaging 1995; 19:244-246.[Medline]
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HISTORY
FINDINGS
