Primary disorders of hyperpigmentation.

A classification of primary hyperpigmentation conditions is presented. The emphasis is on clinical aspects and an attempt has been made to show, when possible, a spectrum beginning with localized involvement and progressing to the more extensive involvement. Most primary hyperpigmentation conditions and syndromes are inherited by autosomal dominant genetics; notable exceptions include incontinentia pigmenti, classic dyskeratosis congenita, and xeroderma pigmentosum. Early German case reports provide insight into the spectrum of uncommon pigmentary conditions, such as dermatopathia pigmentosa reticularis. The Japanese observe pigmentary problems frequently, have presented some of the more unusual cases, and have recently provided us with much-needed research into the problem of abnormal pigmentation.