A 49-year-old African American woman, who was being treated with doxycycline for acne keloidalis nuchae for 7 months, presented to our dermatology clinic with a new eruption in the right axilla of 2 weeks' duration. On physical examination, brown-gray hyperkeratotic plaques were evident in the right axilla only (Figure 1).
Histopathologic examination demonstrated irregular epidermal hyperplasia with an intact granular cell layer and a hyperparakeratotic stratum corneum. In addition, there was a diffuse retention of the keratohyalin granules within the stratum corneum. A diagnosis of granular parakeratosis (GP) was established based on clinical and histopathologic features. A trial of topical calcitriol ointment, 3 μg/g, applied to the area twice a day led to complete resolution within 10 days (Figure 2).
Patel U, Patel T, Skinner RB. Resolution of Granular Parakeratosis With Topical Calcitriol. Arch Dermatol. 2011;147(8):997–998. doi:10.1001/archdermatol.2011.214
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