Syringocystadenoma papilliferum is an infrequent hamartoma of the sweat glands, usually of the scalp or temporal area. We observed a syringocystadenoma papilliferum in a young patient from Senegal. The lesion was unique and presented as a round 4 cm plaque with a red smooth surface. The diagnosis was based on the histologic examination. Complete surgical exeresis was performed. Localization on the knee is very unusual.