Gastric undifferentiated carcinoma, INI1-negative
Among undifferentiated carcinomas of the digestive system (DS-UC), undifferentiated gastric carcinoma (GUC) is one of the rarest epithelial malignancies of the stomach, accounting for 0.1-0.3% of all gastric carcinomas.
The limited data on DS-UC/GUC describe them as aggressive, usually at an advanced stage and with a marked tendency to lymph node metastasis, even when still intramucosal.
The photo above refers to an 84-year-old woman found unconscious at home due to an unknown cause. On admission to the hospital, jaundice and acute liver failure were observed together with the presence of a mesogastric mass strongly suspected on radiology to be neoplastic. Before any further diagnostic/therapeutic steps could be taken, death occurred.
The autopsy reveals the presence of a large antral neoplasm with a maximum diameter of 5.5 cm (
Immunohistochemistry shows a focal positivity for MNF116 broad-spectrum cytokeratins and a dot-like expression of EMA (
From a strictly microscopic point of view, the features of the neoplastic cells suggest the differential diagnosis between a GUC, an EBV-associated carcinoma with lymphoid stroma, an aggressive lymphoma, a metastatic melanoma, a germ cell neoplasm, a PEComa, and a rhabdomyosarcoma (or other types of sarcomas with epithelioid/rhabdoid pattern).
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