Clinical differential diagnoses of acquired hyperpigmentation of the skin are manifold. The rarity and fuzzy demarcation between various entities on the one hand and the alleged insignificance and harmlessness of the dermatoses on the other hand often delay a rapid diagnosis in everyday clinical practice. In the present work the most important clinical differential diagnoses are reviewed. Acquired reticular pigment dermatoses (RPD) of the skin sui generis include Dowling-Degos disease (DDD), Galli-Galli disease (GGD). Further diseases rarely found in Europe are Kitamura disease (RKD), reticular acropigmentation Dohi (RAD) and Haber syndrome (HS). Other acquired more frequent hyperpigmentation of the skin, which may also have a reticular pattern, include acanthosis nigricans, papillomatosis confluens et reticularis Gougerot carteaud, diabetic dermatopathy, and postinflammatory hyperpigmentation. Some of these diseases are particularly indicative of endocrinopathies. In particular, childhood acanthosis nigricans is of great importance in diabetes mellitus screening. Histopathological examination with the clinical problem of acquired hyperpigmentation can be difficult and requires close clinical-pathological correlation.