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Authors: Ko Jin Quek, Junior Medical Officer, South-Western Sydney Local Health District, Sydney, NSW, Australia; Dr Monisha Gupta, Dermatologist, Sydney, Australia. DermNet NZ Editor in Chief: Adjunct A/Prof Amanda Oakley, Dermatologist, Hamilton, New Zealand. Copy edited by Gus Mitchell. January 2020.
Acquired dermal macular hyperpigmentation, also called acquired macular pigmentation of unknown aetiology, comprises three conditions:
The term acquired dermal macular hyperpigmentation is useful because the three conditions overlap. The subtypes may manifest in the same patient, and they lack clear-cut clinical and histological differences .
Acquired dermal macular hyperpigmentation
The epidemiology of acquired dermal macular hyperpigmentation varies depending on the underlying condition.
Erythema dyschromicum perstans can affect any age, sex, and ethnicity, and tends to affect darker-skinned patients. Asian, Middle-Eastern, and Latin American women between the 2nd and 4th decades of life are the most frequently affected . Whereas idiopathic eruptive macular hyperpigmentation develops in the first two decades of life . Lichen planus pigmentosus affects middle-aged people of South Asian and African/Middle Eastern descent .
The exact cause of acquired dermal macular hyperpigmentation is unknown.
Proposed theories for the pathogenesis of acquired dermal macular hyperpigmentation include:
The pigmentation in acquired dermal macular hyperpigmentation is often due to persistent melanophages in the dermis. The reason the melanophages do not clear as usually occurs is unknown .
Acquired dermal macular hyperpigmentation presents with blue, brown, slate grey or brownish-black macules, which can change in size and morphology over time.
Acquired dermal macular hyperpigmentation is generally asymptomatic, although lichen planus pigmentosus is sometimes pruritic in its early phases.
No detrimental serious long-term medical complications arise from acquired dermal macular hyperpigmentation. However, it impacts on the quality of life in people with skin of colour due to cosmetic visibility and slow resolution.
The diagnosis of acquired dermal macular hyperpigmentation and its subtypes are based on the cutaneous features and detailed history.
A detailed history is required to exclude medications, virus infection, and inflammatory skin conditions.
Patch testing may be indicated to exclude allergic contact dermatitis if there is a possible contact factor.
Dermoscopy is useful in the diagnosis and monitoring of acquired dermal macular hyperpigmentation. Findings may include :
Histological features of acquired dermal macular hyperpigmentation on skin biopsy may include and help to determine the diagnosis:
A variety of other skin conditions appear similar to acquired dermal macular hyperpigmentation, such as:
The treatment of acquired dermal macular hyperpigmentation depends on the subtype and its duration, but many therapies have been tried with little or no benefit.
Idiopathic eruptive macular hyperpigmentation tends to resolve spontaneously within months to years . In contrast the pigmentation of lichen planus pigmentosus can persist for decades and erythema dyschromicum perstans tends to be chronic and progressive .
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