A woman with mycosis fungoides, vitiligo, and a new hand nodule.

A 70-year-old African American female with a history of stage IV mycosis fungoides in remission presented with a gradually enlarging, red, ulcerated nodule on her right dorsal hand. The lesion was biopsied, and it showed intraepidermal proliferation with cytologic atypia and increased vasculature in the papillary dermis. Immunohistochemical staining indicated a yes-associated protein 1 (YAP1) rearrangement, confirmed by RNA sequencing, revealing a YAP1::MAML2 (mastermind-like transcriptional coactivator 2) fusion. The lesion was diagnosed as an eccrine porocarcinoma (EPC). The occurrence of EPCs following radiotherapy or trauma has been documented. This case highlights the importance of considering EPCs in patients with extensive skin treatments and immunosuppression history.