Fig. 3: Visceral SMARCA4-deficient undifferentiated malignant neoplasms are histologically highly similar to cutaneous counterparts.

A shows a primary lung SMARCA4-deficient undifferentiated malignant neoplasm composed of pleomorphic epithelioid cells, frequent mitoses, and apoptotic debris. This tumor shows complete loss of SMARCA4 expression (with retention of expression in non-noeplastic cells) (B). A primary rectal SMARCA4-deficient undifferentiated malignant neoplasm shows classic epithelioid morphology with variably prominent nucleoli (C). This tumor shows complete loss of SMARCA4 expression (with retention of expression in non-neoplastic cells). Interestingly, the rectal epithelium also shows loss of SMARCA4 expression, which is of uncertain significance but suggests that it may represent neoplastic or pre-neoplastic epithelium (D). All images depict 200x magnification.