[Relations between acanthosis nigricans benigna and pseudoacanthosis nigricans].

A 37-year-old man is reported who, as a schoolboy and during puberty, showed the clinical aspects of acanthosis nigricans benigna. In correlation with an obvious obesity the picture has meanwhile developed into pseudoacanthosis nigricans. On the basis of this case the delimitating criteria of the various acanthosis nigricans subgroups and their etiologic factors are discussed.