Multiple fibrofolliculomas (Birt-Hogg-Dubé) associated with a large connective tissue nevus.

Multiple follicular tumors of the type recently described by Birt and colleagues as fibrofolliculomas were observed in the dorsal skin of a white man in association with a large connective tissue nevus. No signs of systemic disease or phakomatosis were present. This type of lesions represents benign neoplasia of the fibrous root sheath of the hair follicle in association with proliferations of the infundibular portion of the outer epithelial root sheath. Its existence supports the view that the mesodermal portions of the pilar apparatus can become neoplastic, and also provides another example of the close interactions existing between the ectodermal and mesodermal components of the hair follicle.