Analyzing the morphological spectrum of epithelioid fibrous histiocytoma and the immunohistochemical performance of the ALK D5F3 and ALK1 clones.

Epithelioid fibrous histiocytoma (EFH) is a cutaneous neoplasm driven by translocations of the anaplastic lymphoma kinase (ALK) gene, which can be demonstrated by immunohistochemical (IHC) analysis. We analyzed the performance of two ALK clones, D5F3 and ALK1, in a cohort of EFHs and described the range of architectural variation of these lesions. TFE3 IHC was performed in ALK-negative EFHs.