Recurrent cutaneous metaplastic synovial cyst.

Reported here is the first case of a recurrent cutaneous metaplastic synovial cyst (CMSC). The CMSC is a recently described lesion that is histologically characterized by a cystic cavity lined by cells resembling metaplastic synovium overlying villous connective tissue cores. The lesion clinically appears as a tender subcutaneous nodule and may often be misdiagnosed as a suture granuloma. Although the actual cause is unclear, a history of trauma usually precedes its onset. Here we present a case of CMSC in a 34-year-old white male, which recurred at the same site following excision of an epidermoid cyst. CMSCs are unique lesions that should be included in the differential diagnosis of tender subcutaneous swellings following surgical trauma.