[Hamartoma of the sebaceous follicle. An immunohistologic analysis with cytokeratins].

A 62-year-old man presented with a nodule 2 cm in diameter on his left cheek, which he had had since childhood. Histological examination showed a circumscribed dermal nodule composed of sebaceous lobules attached to sebaceous ducts and to an infundibular cyst-like structure connected to the epidermis. The wall was lined with squamous epithelium with a stratum granulosum. This structure was reminiscent of a sebaceous follicle. In addition, a melanocytic naevus of the compound type was found. Immunohistological investigations of the tumour with various cytokeratins revealed a pattern of expression characteristic for the mature sebaceous follicle.