Metastatic Porocarcinoma Effectively Managed by Pembrolizumab

Eccrine porocarcinoma (EPC) is a rare malignancy of the sweat glands. Currently, there is no standard algorithm for its presentations, diagnosis, and management. However, immunotherapy is an emerging option that may be crucial to the treatment of EPC. This report presents a case of a 79-year-old male who had a skin biopsy of an anterior scalp lesion, which revealed EPC. The patient underwent Mohs micrographic surgery to excise the tumor followed by two additional Mohs surgeries for recurrence and adjuvant radiotherapy. A follow-up positron emission tomography (PET) scan revealed yet another recurrence at the scalp as well as metastases to the left parotid gland and left submandibular lymph node. The patient was started on immunotherapy with pembrolizumab, a programmed cell death protein 1 (PD-1)/programmed death-ligand 1 (PD-L1) inhibitor, and later achieved remission. This report demonstrates the effective management of EPC using immunotherapy with pembrolizumab.