A case ofYAP1andNUTM1rearranged porocarcinoma with corresponding immunohistochemical expression: Review of recent advances in poroma and porocarcinoma pathogenesis with potential diagnostic utility

Porocarcinoma is a rare malignant adnexal tumor with predilection for the lower extremities and the head and neck region of older adults. This entity may arise de novo or in association with a benign poroma. Porocarcinoma's non-specific clinical appearance, immunohistochemical profile, and divergent differentiation may occasionally be diagnostically challenging. Recently, highly recurrentYAP1andNUTM1gene rearrangements have been described in cases of poroma and porocarcinoma. In this report, we present a case of porocarcinoma with squamous differentiation in an 81-year-old woman which harbored rearrangement of theYAP1andNUTM1loci and was diffusely immunoreactive for NUTM1. We discuss the recent advancements in the pathogenesis of poromas and porocarcinomas with emphasis on the clinical utility of the NUTM1 antibody.

Automated summary

Porocarcinoma is a rare malignant adnexal tumor that often occurs in older adults on the lower extremities and head and neck region. The clinical presentation, immunohistochemical profile, and differentiation of porocarcinoma can be diagnostically challenging due to their non-specific nature. Recent studies have shown highly recurrent YAP1 and NUTM1 gene rearrangements in cases of poroma and porocarcinoma, with emphasis on the clinical utility of the NUTM1 antibody.