Vulvar Pigmented Epithelioid Melanocytoma With a Novel HTT-PKN1 Fusion: A Case Report.

Pigmented epithelioid melanocytoma is a highly pigmented, predominantly dermal melanocytic neoplasm composed by epithelioid and spindled melanocytes. It is characterized by a limited number of specific genomic alterations principally involving protein kinase A regulatory subunit alpha (PRKAR1A) and fusion of protein kinase C alpha isoform (PRKCA). However, in some of these neoplasms, no genetic aberrations have been detected. We performed genomic analysis of a nodular heavily pigmented intradermal proliferation composed of monomorphic epithelioid melanocytes with slight cytologic atypia consisting with pigmented epithelioid melanocytoma occurring on the vulva of a 24-year-old woman. A novel fusion transcript HTT-PKN1 and an ATM (Val410Ala) missense mutation were found. No other mutations including TERT-promoter hotspot mutation analysis were detected. The data expand the spectrum of molecular alterations in pigmented epithelioid melanocytoma.