Abstract: 【Abstract】 Acquired dermal macular hyperpigmentation has been newly introduced as a term in the field of pigmentary skin diseases in recent years, aiming to unify diseases previously classified separately as Riehl's melanosis, pigmented contact dermatitis, lichen planus pigmentosus, and ashy dermatosis （erythema dyschromicum perstans）. These disorders predominantly affect areas such as the face, neck, and trunk, and are notably disfiguring, exerting a profound impact on patients′ psychological health and social life. Currently, the main clinical challenges in managing these conditions include their unclear etiology and pathogenesis, difficulties in differential diagnosis, and limited therapeutic efficacy. In light of this situation, this article outlines the diagnostic and therapeutic challenges associated with Riehl's melanosis and other types of acquired dermal macular hyperpigmentation, and provides potential countermeasure analysis.

Key words: Skin pigmentation, Acquired dermal macular hyperpigmentation, Riehl′s melanosis, Diagnosis, Therapy, Patch test, Photosensitivity