A Case of Syringolymphoid Hyperplasia with Follicular Mucinosis

Syringolymphoid hyperplasia (SLH) is an extremely rare histopathological entity with fewer than 40 cases reported in the literature. SLH have been seen as both benign lesions and in association with T-cell lymphoproliferative lesions. A 20-year-old male presented with a solitary, infiltrated plaque on the left cheek initially diagnosed as a sebaceous carcinoma at an external institution. A repeat biopsy demonstrated prominent follicular mucinosis (FM), squamous metaplasia of the eccrine coils, and a moderately dense perieccrine lymphocytic infiltrate mimicking eccrine carcinoma. The lesion was subsequently diagnosed as SLH with associated FM, an entity that has been previously reported in 12 cases, including this current case. This case highlights the characteristic features of a rare entity, emphasizes the potential for misdiagnosis of SLH, and adds to the current series of SLH described in the literature.