By Gary M. White, MD
Multiple blue macules and patches on the back of a teenager.
Also known as erythema dyschromicum perstans, ashy dermatosis is an unusual dermatosis that shows a strong geographic preference for Mexico and Central and South America.
Clinically, one sees bluish-gray macules and patches scattered on the trunk, arms, and face. Erythema may occur at the border early in the course of the disease. Most patients are less than 30 years of age. There are anecdotal reports of it being associated with various medications, e.g., ethambutol for Tb, and omeprazole.
For proper diagnosis, it is important to biopsy the edge of a lesion. Taking skin from the center may miss the active area that provides the characteristic histologic picture. As part of the differential diagnosis, lichen planus pigmentosus should be considered.
Topical steroids may be tried, especially if there seems to be an inflammatory component. Clofazamine was used with benefit [AD 1997;133;325]. It was given either 100 mg every other day to patients weighing less than 40 kg or 100 mg every day to patients weighing more than 40 kg. It was continued for 3 months, then reduced to 200 mg/wk and 400 mg/wk, respectively. Other anecdotal treatments include hydroxychloroquine, dapsone, and sunscreen use.
Low dose, isotretinoin at 0.25 mg/kg/day for 4 months improved one patient by 90% [JAMADerm 2016;152;842].
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