Cutaneous myoepithelioma with EWSR1 gene rearrangement and its differentials: A diagnostic challenge.

ABSTRACT

Cutaneous myoepithelioma is a rare benign soft tissue neoplasm of myoepithelial cells involving the skin and subcutis. These tumors can be diagnostically challenging. The plasticity of myoepithelial cells leads to wide variability in the cytomorphology, immunophenotype, and genetic features of myoepithelioma. Their protean presentations may mimic malignant neoplasms. Therefore, distinction from malignancy is essential. Herein, we report a case of cutaneous myoepithelioma presenting similarly to Ewing sarcoma, with small round blue cells and an EWSR1 rearrangement. Our case highlights the important morphologic, immunohistochemical, and cytogenetic features of this benign basaloid cutaneous tumor.