SMARCB1 (INI-1)-Deficient Myoepithelioma-Like Tumor in the Perineal Region of a Male Patient: A Case Report.

SMARCB1/INI1 is a critical tumor suppressor gene involved in chromatin remodeling, and its loss of expression is linked to various malignancies. We report a rare case of SMARCB1-deficient myoepithelioma-like tumors in the male perineum. A 72-year-old man presented with a progressively enlarging perineal mass, accompanied by urinary difficulties and increased frequency. Imaging with positron emission tomography/computed tomography revealed an ill-defined mass with increased tracer uptake, suggesting malignancy. Histological examination showed myoepithelial differentiation, and immunohistochemistry confirmed the loss of SMARCB1 expression. The tumor exhibited an indolent course with no evidence of metastasis or recurrence during an 8-month follow-up period. This report highlights a rare presentation of SMARCB1-deficient myoepithelioma-like tumors in the male perineum and provides valuable insights into their diagnosis and clinical behavior.