Acneform lesions strictly confined to a Becker's nevus were observed in a 
18-year-old man. Histologically, a granulomatous folliculitis with partial 
destruction of the epithelial root sheath and follicular cysts with focal 
penetration of keratin into the surrounding dermis were present, ruling out acne 
vulgaris. The concept of Becker's nevus as a complex nevogenic process, 
affecting ectodermal, neuroectodermal, and mesenchymal structures, also in terms 
of dysfunction of the pilary complex, is suggested.