Gastric undifferentiated carcinoma, INI1-negative.

HMB-45). EBV, CD99, CD117, SALL4, and Glypican3 were also negative. Finally, the absence of expression of INI1 (Figure 1D) is noteworthy. 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). 1 Based on the overall immunomorphological data, which allows us to exclude the other aforementioned hypotheses, we make the final diagnosis of GUC with rhabdoid morphological aspects and, according to the literature, lack of immunophenotypic expression for INI1.