Case report metastatic SMARCB1 (INI1)-deficient gastric undifferentiated carcinoma in pleural effusion: A case report and literature review.

INI1-deficient gastric undifferentiated carcinoma is a rare tumour that may present as high-grade epithelioid morphology without apparent rhabdoid tumour cells. Syncytial tumour cells may be a crucial clue in such cases, especially in cytological specimens. Cell block and immunocytochemical staining can be valuable tools in achieving an accurate diagnosis.