Cutaneous Syncytial Myoepithelioma: A Unique Variant Worth Recognizing.

Cutaneous syncytial myoepithelioma is a recently characterized variant of cutaneous myoepithelioma with a distinct histopathological and immunohistochemical profile. It is more common in men and predominately involves upper and lower extremities. Microscopically, it is a dermal tumor with a characteristic solid syncytial growth pattern displaying positivity with EMA and S100 immunohistochemical stains. Lately, EWSR1-PBX3 fusion has been documented in a vast majority. Although it follows a benign clinical course, its histopathological differential diagnosis includes clinically aggressive neoplasia. This contribution summarizes the derivation, clinical presentation, histopathological and immunohistochemical features, molecular genetics, pertinent differential diagnosis, and behavior of this unique cutaneous appendageal tumor.