Porocarcinoma with YAP1-NUTM1 Fusion Presenting as a NUT Immunohistochemistry Positive Lymph Node Metastasis.

Porocarcinoma is a rare entity, and typically only enters the differential diagnosis when the clinical consideration is a cutaneous neoplasm. In an alternative clinical scenario such as the approach to tumors of the head and neck, porocarcinoma is not typically a consideration. In the latter scenario, as seen in our case, positivity with NUT IHC led to the initial misdiagnosis of NUT carcinoma. This case represents an important presentation of porocarcinoma that will occur not infrequently, and pathologists must be aware of this presentation to avoid this pitfall. This article is protected by copyright. All rights reserved.