Intra-abdominal desmoplastic small round cell tumor

Background. Intra-abdominal desmoplastic small round cell tumor is a rare m alignancy with a predilection for young males. Unique histological and immu nocytochemical features distinguish the tumorfrom other members of the fami ly of small round cell tumors of infancy and childhood The aggressive natur e of turner spread relative insensitivity to chemotherapy, and generally in complete resectability result in a very poor prognosis. The authors report a case of a 39-year-old man with diffuse abdominal and pelvic involvement o f intra-abdominal desmoplastic small round cell tumor treated with aggressi ve chemotherapy and surgery. Methods: Computed-tomography (CT)-guided biopsy of an omental mass was perf ormed Histologically, discrete nests of uniform closely packed malignant ce lls were distributed in a background of focally desmoplastic stroma. Immuno cytochemistry demonstrated positivity for epithelial, mesenchymal, and neur al markers. On the basis of these unique histological and immunohistochemic al characteristics, the diagnosis of desmoplastic small round cell tumor wa s made. The patient was treated with aggressive neoadjuvant chemotherapy co nsisting of a high-dose alkylator -based combination regimen, followed by s urgery. Results: The patient had a 10 to 15 percent regression in tumor mass in res ponse to chemotherapy. Laparotomy revealed two large omental masses, anothe r large mass adherent to the left colon and pelvic sidewall, and diaphragma tic, peritoneal and mesenteric studding with small nodules. Complete surgic al resection was not possible. Conclusions: Intra-abdominal desmoplastic small round cell tumor remains an aggressive malignancy with an extremely poor prognosis. Although some resp onse to chemotherapy may be possible, complete resection is rare, and surgi cal efforts ave general palliative.