Macular pigmentation of uncertain aetiology revisited: two case reports and a proposed algorithm for clinical classification

Abstract

Ashy dermatosis, erythema dyschromicum perstans, lichen planus pigmentosus and idiopathic eruptive macular pigmentation are various types of acquired macular hyperpigmentation disorders of the skin described in literature. However, a global consensus on the definitions of these entities is lacking. We report two cases of acquired macular (hyper)pigmentation of uncertain aetiology diagnosed as ashy dermatosis and attempt to clarify the various confusing nosologies based on existing literature. We infer that acquired small and large macular pigmentation of uncertain aetiology should be considered separate from that associated with lichen planus. We also propose a diagnostic algorithm for patients with acquired macular hyperpigmentation.

Ashy dermatosis: A comprehensive review

“…An approach to diagnosis for the acquired macular pigmentary disorders of unknown significance can be made using the algorithm devised by Chandran and Kumarasinghe [20]. This allows the clinician to make a confident diagnosis by excluding the other two simulatory conditions, idiopathic eruptive macular pigmentation and Riehl's melanosis.…”

“…However, the border can be difficult to discern in darker skinned populations [12]. A descriptive term such as macular pigmentation of uncertain aetiology should be used to describe the two conditions, which have similar clinical picture, histology and prognosis [20].…”

“…A n a l g o r i t h m d e v i s e d b y C h a n d r a n a n d Kumarasinghe [20] can be used to make an approach to diagnosis in these conditions. The salient features are:…”

“…Lichen planus pigmentosus: Past or current evidence of lichen planus, with supportive histological features including band-like infiltrates, basal layer hyperpigmentation and presence or absence of vacuolar degeneration of basal cells [20].…”

Facial Hyperpigmentation in Skin of Color: Special Considerations and Treatment

“…In contrast to the dermal pigmentation seen in LPP, that of EDP is deeper within the dermis, producing the blue-gray color of the lesion [102]. Asymptomatic brown macules, mainly on face, neck, proximal extremities, and trunk [121] Basal layer pigmentation with occasional dermal melanophages, some specimens show papillomatosis [122,123] Unknown Post chikungunya pigmentation…”