Acquired dermal macular hyperpigmentation: an update on terminology, diagnosis and management

Abstract

Lichen planus pigmentosum, erythema dyschromicum perstans/ashy dermatosis, and pigmented contact dermatitis (also known as Riehl's melanosis or pigmented cosmetic dermatitis), are acquired disorders of skin hyperpigmentation of uncertain etiology that have shown considerable clinical-pathological and dermoscopic overlap. Consequently, the nosology of these conditions has been under debate, and to simplify their study, experts have suggested a unifying term that includes all these dermatoses. Thus, different denominations have been proposed; however, the generic term “acquired dermal macular hyperpigmentation” (ADMH), presented in 2017 by the Pigmentary Disorders Society of India, seems to be the most accepted to date. ADMH describes disorders clinically characterized by small and large, usually asymptomatic, greyish-brown hyperpigmented macules/patches; that histopathologically show current or resolved interface dermatitis and pigmentary incontinence, without any signs of previous inflammation. This is a complex condition to treat due to the dermal location of the pigment deposit, and there are minimal data on effective treatments. Progress has been achieved in key aspects of epidemiology, pathogenesis, histology, and dermoscopy of ADMH, and even a scale to assess the severity of the disease has been validated; however, a global consensus has not yet been established on the nomenclature and the entities that should be considered under the spectrum of ADMH, and more studies are needed to explore effective therapies for its management.