Disorders of Hyperpigmentation

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Disorders of Hyperpigmentation





Approach to Disorders of Hyperpigmentation




Circumscribed Hyperpigmentation




Melasma



A very common, acquired disorder characterized by symmetric, hyperpigmented patches with irregular borders, resulting from an increase in epidermal and/or dermal melanin; favors the face (see below) > mid-upper chest and extensor forearms.


Seen primarily in women; increased prevalence in individuals with skin phototypes III–IV.


Pathogenesis thought to be related to hyperfunctional melanocytes that are stimulated by exacerbating factors, such as sun exposure and hormones (e.g. pregnancy, oral contraceptives).


Three classic clinical patterns based on distribution: centrofacial (most common), malar, and mandibular (Fig. 55.2).



Classically, melasma was also classified based on findings from Wood’s lamp examination: lesions that enhance imply an increase in epidermal melanin and lesions that do not enhance imply an increase in dermal melanin; however, mixed epidermal and dermal melasma patterns are common.


In northern latitudes, lesions tend to fade during the winter months; melasma tends to be more persistent in darkly pigmented individuals.


DDx: postinflammatory hyperpigmentation, drug-induced (e.g. minocycline, amiodarone), acquired bilateral nevus of Ota-like macules (especially in Asian women), actinic lichen planus, pigmented contact dermatitis, exogenous ochronosis due to the application of hydroquinone-containing bleaching agents, erythromelanosis faciei.


These other disorders are distinguished from melasma based on historical aspects (e.g. drug ingestion, application of topical medications or cosmetics, previous inflammation), color (e.g. clusters of nevus of Ota-like macules are typically blue-gray in color), distribution pattern, histologic features, and primary lesions, if present.


Treatment options are outlined in Table 55.1; typically epidermal hyperpigmentation responds best to treatment.




Drug-Induced Circumscribed Hyperpigmentation and Discoloration



A wide range of medications and chemicals can cause hyperpigmentation or discoloration in circumscribed, diffuse, and even linear patterns; longitudinal or horizontal melanonychia may also be present.


The most common culprits of drug-induced circumscribed hyperpigmentation and discoloration are minocycline and the antimalarials (Table 55.2; Figs. 55.355.6).







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Apr 22, 2016 | Posted by in Dermatology | Comments Off on Disorders of Hyperpigmentation

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