Cutaneous Hemangioma With Epithelioid Features Harboring a TPM4::ALK Fusion

Vascular neoplasms comprise a heterogeneous group of tumors ranging from benign to malignant, increasingly defined by recurrent gene fusions. In this report we describe a cutaneous hemangioma with epithelioid features harboring a TPM4::ALK gene fusion in a 43‐year‐old female. On histology, this dermal‐based lesion was composed of epithelioid endothelial cells with no overt cytologic atypia and abundant cytoplasm. Immunohistochemistry showed the epithelioid cells were positive for ERG and showed diffuse intracytoplasmic ALK‐1 expression. The fusion was detected via RNA sequencing, highlighting ALK as a potential oncogenic driver in this tumor. The morphology resembled epithelioid hemangioma, a benign vascular tumor known to harbor FOS gene rearrangements. This case represents the second known instance of a cutaneous hemangioma with epithelioid features and a TPM4::ALK fusion. Additional studies are needed to clarify the biological behavior and classification of these tumors within the spectrum of fusion‐driven vascular neoplasms.