Drug-induced pigmentation

Abstract

Around 10% to 20% of all cases of acquired hyperpigmentation are drug-induced. The underlying pathogenesis for drug-induced pigmentation includes melanin accumulation, drug accumulation, toxic effects on melanocytes, and hypersecretion of adrenocorticotropic hormone and melanocyte-stimulating hormone among others. A step-by-step approach might help the dermatologist to diagnose a case of drug-induced pigmentation. Initial history should include a list of drugs taken, duration of intake of each drug, dose of the drug, and latency between drug intake and the onset of pigmentation. Examination findings might reveal specific patterns of pigmentation such as fixed drug eruption, serpentine supravenous pigmentation, flagellate pigmentation, melasma-like pigmentation, or reticulate pigmentation. The color of the pigment also helps in making a diagnosis. Besides, examination of the mucosa, hair, nails, and teeth is also essential. The histopathological examination might reveal whether the color is due to the drug itself, melanin, lipofuscin, or hemosiderin. Special staining, examination under polarized light, and electron microscopy are useful adjuncts in making a diagnosis. Often, drug-induced pigmentation is a diagnosis of exclusion and requires evaluation for other causes of pigmentation. Treatment options for drug-induced pigmentation include lowering the dose or replacing the drug with an effective alternative. Photoprotection and sunscreens also play an important role in treatment. Knowledge of the various patterns of drug-induced pigmentation is essential for all dermatologists to manage this condition.