DSRCT is a rare neoplasm, firstly recognized in 1987 by Sesterhenn et al. who described 17 cases of young males with undifferentiated malignant epithelial tumor arising in the pelvis or scrotum.1,6,12
Ever since only case reports or small series of patients have been announced, making diagnosis and management of this disease a challenge for the physicians.
DSRCT shares characteristics with other small round cell malignancies including Ewing's Sarcoma, small cell Mesothelioma, Neuroblastoma, Lymphoma, Primitive Neuroectodermal tumor, Rhabdomyosarcoma and Wilm's tumor. That is why the DSRCT was until recently classified as a soft tissue undifferentiated sarcoma.6,7,10,13
Pathology reveals clusters of small to medium sized cells with hyperchromatic nuclei and increased nuclear/cytoplasm ratio, surrounded by a dense desmoplastic stroma.6
Immunohistochemical findings suggest a trilinear coexpression including the epithelial marker keratin, the mesenchymal markers desmin and vimentin, and occasionally the neuronal marker neuron-specific enolase (Primitive neuroectodermal tumors/Ewing Sarcoma – PNET/ES – are desmin negative, neuroblastoma is vimentin and desmin negative, small cell mesothelioma is desmin, CD15, CD57 negative).8–11
Recent studies have shown that DSRCTs present a reciprocal chromosomal translocation, t(11;22)(p13;q11 or q12) that results in fusion of exon 7 of the Ewing's sarcoma gene EWS on chromosome 22 with exon 8 of the Wilms’ tumor suppressor gene WT1 on chromosome 11. The EWS/WTI transcript is diagnostic of this tumor and codes for a protein that acts as a transcriptional activator that fails to suppress tumor growth.4,13,14
This extremely rare tumor chiefly affects males (96%) in their second or third decade of life. It behaves aggressively and only 29% of patients survive up to 3 years.12
No ethnic predisposition or other known risk factors have been identified specific for the disease. The neoplasm usually appears as an extensive intraabdominal or less often endopelvic mass with widespread peritoneal and lymphatic dissemination, without an apparent organ of origin. Other areas less often affected may include lymph nodes, the lining of the abdomen, diaphragm, spleen, liver, lungs, testicles and ovaries. The most common sites of metastatic spread are the liver, lungs and bones.
Despite the enormous size the tumors can grow to, there are few early warning signs. The majority of patients are young and healthy as the tumor grows and spreads uninhibited within the abdomen or pelvis. The most common presenting symptoms and signs of intraabdominal DSRCT include abdominal pain, distension, lack of appetite, a palpable abdominal mass, which are nonspecific and nondiagnostic.7
The most common and useful imaging tool is the CT scan with intravenous and per os contrast. Although the CT scan is not diagnostic, the pattern of tumor distribution can be very suspicious for DSRCT. Bulky, heterogeneous peritoneal soft tissue masses without an apparent organ-based primary and mesenteric lymphadenopathy are characteristics of DSRCT. Diagnosis can only be made after removal of the suspicious mass and histological analysis with immunohistochemical demonstration of the trilinear nature of the tumor.7,12
Fine needle aspiration cytology has also been used for the diagnosis but still it's not the most preferable way, since molecular cytogenetics require larger biopsies.2,12
The ideal therapeutic strategy for treating this neoplasm is still unclear due to the rarity of the tumor and consequently the limited experience. Most reports suggest total resection of the mass and postoperative multiagent chemotherapy and radiation therapy as the best therapeutic options. Total resection is not often feasible because of the numerous peritoneal implants. Some authors suggest preoperative chemotherapy as a way of shrinking the widespread mass and reducing its vascularity. Intraperitoneal hyperthermic chemoperfusion has also been administered as an effort to reduce the bulk of the tumor. The experience with pseudomyxoma peritonei is behind this concept. Despite the combined therapeutic approach, including surgery and chemoradiation therapy, the prognosis for these patients remains very poor, especially for those with metastatic disease – 29% for a 3-year survival and just 18% for a 5-year survival.12,15