Carcinosarcoma of the Gallbladder with Chondrosarcomatous Differentiation and Intracytoplasmic Eosinophilic Hyaline Globules (Thanatosomes): A Report of a Case and Review of the Literature.

A 52-year-old woman presented with abdominal pain and vomiting. Computed tomography (CT) scan of the abdomen revealed a huge exophytic gallbladder mass displacing or invading the surrounding structures. The patient underwent radical cholecystectomy, transverse colectomy, distal gastrectomy, and liver bed resection. Histologically, the tumor showed both carcinomatous and sarcomatous components, with prominent chondrosarcomatous differentiation. In addition, several malignant cells showed intracytoplasmic eosinophilic hyaline globules (Thanatosomes). The tumor showed metastatic deposits to the omentum, the liver, and the peripancreatic lymph nodes. We report this unusual case and present a review of all cases of carcinosarcoma of the gallbladder with chondrosarcomatous differentiation.

Malignant gastrointestinal neuroectodermal tumor: a case report and review of the literature.

BACKGROUND: Malignant gastrointestinal neuroectodermal tumor (GNET) is an extremely rare entity that was first described by Zambrano et al. in 2003 as "Clear cell sarcoma-like tumor of the gastrointestinal tract". It shares some of the histological features of clear cell sarcoma (CCS) but lacks the immunohistochemical reactivity for melanocytic markers. We report a case of GNET that was initially misdiagnosed as gastrointestinal stromal tumor (GIST). Recognizing this entity is important to avoid misdiagnosis. CASE PRESENTATION: A case of an 18-year-old male presented with a small intestinal tumor. Histologically it was characterized by polygonal cells arranged in pseudoalveolar pattern and situated in the muscularis propria. Scattered osteoclast-like multinucleated giant cells were also noted. The neoplastic cells were positive for S-100 protein and negative for HMB-45, Melan A, smooth muscle actin, desmin and CD117. EWSR1 gene rearrangement was detected by fluorescence in situ hybridization (FISH) analysis. The patient returned with recurrence after 36 months' management by surgical resection and died one year later. CONCLUSIONS: GNET can be mistaken histologically for other non-epithelial gastrointestinal tumors. Awareness of its existence and diagnostic criteria by the pathologist is necessary to avoid misdiagnosis, particularly as GIST, CCS or malignant peripheral nerve sheath tumor (MPNST).