Desmoplastic small round cell tumor of the pancreas: An unusual primary site for an uncommon tumor

Desmoplastic Small Round Cell Tumor of the Kidney: Report of a Case, Literature Review, and Comprehensive Discussion of the Distinctive Morphologic, Immunohistochemical, and Molecular Features in the Differential Diagnosis of Small Round Cell Tumors Affecting the Kidney

Desmoplastic small round cell tumor (DSRCT) is a rare, highly aggressive neoplasm typically presenting with widespread involvement of the abdominopelvic peritoneum of adolescent males, usually without organ-based primary. Although it is believed to originate from the serous (mainly peritoneal) membranes, intracranial, sinonasal, intraosseous, and other soft tissue sites are also documented. A chromosomal translocation t(11:22)(p13;q12) signature that fuses EWSR1 and WT1 genes results in the production of a chimeric protein with transcriptional regulatory activity that drives oncogenesis. Integration of clinical, morphologic, immunohistochemical, and genetic data is necessary to arrive at the correct diagnosis, especially when the tumor arises in an atypical site. A 15-year-old male presented with hematuria and was found to have a large renal tumor associated with adrenal, liver, lung, and bone metastases. Histopathologic and immunophenotypic features were distinctive for DSRCT. This diagnosis was confirmed by means of fluorescence in situ hybridization and cytogenetic analysis, which documented the pathognomonic t(11;22) translocation, and by reverse transcription polymerase chain reaction on snap-frozen tissue, which revealed the EWSR1/WT1-specific chimeric transcript. Despite high-dose chemotherapy and radiation therapy targeted to a single T11 vertebral metastasis, the disease progressed, and the patient died 4 years after the diagnosis. A search of electronic databases for DSRCT yielded 16 cases of well-documented renal primaries out of around 1570 cases from all sites gathered from the global literature. Desmoplastic small round blue cell tumor and other primary renal tumors considered in the differential diagnosis with DSRCT are discussed.

Desmoplastic Small Round Cell Tumor of Pancreatic Origin in a Young Child: A Case Report and Review of Literature

BACKGROUND Desmoplastic small round cell tumor (DSRCT) is a rare lethal malignant tumor with young male predominance. The majority of cases arise in the abdominopelvic region and are hypothesized to have a mesothelial origin. However, extra-abdominal and extraperitoneal DSRCT have been reported. It is extremely uncommon for the pancreas to be a primary site for DSRCT, and only 5 cases have previously been reported in the English literature. Clinically, DSRCT has a wide range of presentations from asymptomatic to life-threatening comorbidity, and it responds poorly to treatment despite aggressive therapy. CASE REPORT We report a previously healthy 9-year-old boy with an incidentally discovered abdominal mass of pancreatic origin. All necessary laboratory investigations were within normal limits. Computed tomographic imaging showed a huge left-side retroperitoneal mass measuring 15 cm in the greatest dimension that was accompanied by vascular encasement. The mass was resected successfully. Histopathological examination along with ancillary tests favored a diagnosis of DSRCT over other small round blue cell tumors. Detection of translocation t(11;22)(p13;q12) with EWSR1-WT1 gene fusion, based on reverse transcription-polymerase chain reaction analysis, confirmed the diagnosis. Approximately 7 months later, the tumor recurred with mesenteric lymph nodes metastasis and the child was placed on palliative therapy. CONCLUSIONS It is worthwhile to consider DSRCT in the differential diagnosis of small round blue cell tumors, even in unusual sites, in a pediatric age group. Due to the poor prognosis, owing to chemotherapy resistance and a high rate of recurrence with significant tumor burden, reaching a precise diagnosis of DSRCT is essential. Almost all cases harbor the hallmark molecular alteration of t(11;22)(p13;q12) with EWSR1-WT1 gene fusion. Debulking surgery paired with a chemotherapy regimen comprising vincristine, doxorubicin, and cyclophosphamide and ifosfamide + etoposide has been shown to improve overall survival rate compared with other chemotherapeutic agents. However, no targeted therapeutic modality has been developed.

Magnetic resonance imaging of less common pancreatic malignancies and pancreatic tumors with malignant potential

Pancreatic tumors are an increasingly common finding in abdominal imaging. Various kinds of pathologies of the pancreas are well known, but it often remains difficult to classify the lesions radiologically in respect of type and grade of malignancy. Magnetic resonance imaging (MRI) is the method of choice for the evaluation of pancreatic pathologies due to its superior soft tissue contrast. In this article we present a selection of less common malignant and potentially malignant pancreatic neoplasms with their characteristic appearance on established MRI sequences with and without contrast enhancement.