Axillary granular parakeratosis

A healthy 62-year-old African-American woman had noted an intermittent erup tion in both axillae for 5 years. She had been using a well-known, brand na me, roll-on deodorant-antiperspirant 1 month prior to the start of her erup tion. She continued to use the same product intermittently for years despit e this eruption, and noticed improvement after stopping it for a short peri od of time. She denied any erythema, pruritus, or foul odor and denied any relation to clothing or environmental temperature. The patient had tried no other treatment for her eruption prior to her clinic visit. The lesions co nsisted of well-demarcated, linear, hyperpigmented, brown, thin, vegetative plaques in her axillae, which peeled off with gentle manipulation (Figs 1 and 2). A potassium hydroxide (KOH) preparation was performed, as well as fungal cu ltures of the lesion. Both the fungal cultures and the KOH preparation were negative. A biopsy of the right axillary lesion was performed on her first clinic visit, and showed a thick stratum corneum with compact parakeratosi s, vascular dilatation, and a mild lymphohistiocytic infiltrate. The unique histopathologic findings were the presence of keratohyalin granules retain ed in the stratum corneum and the retention of the granular layer despite t he overlying compact parakeratosis (Figs 3 and 4).