Violaceous Patches in the Axilla: JAMA case report
A man in his 40s presented with a 3-month history of discrete, dark red, circular lesions in his right axilla. He endorsed severe pruritus at these sites that would wake him up at night. He denied any recent trauma or history of similar lesions. He denied associated pain, blisters, or systemic symptoms (eg, fever, chills).

His medical history was unremarkable, and he noted no environmental triggers or new medications. Treatment with over-the-counter hydrocortisone cream, ketoconazole cream, and discontinuation of underarm deodorant yielded no improvement. Physical examination revealed 3 well-circumscribed, violaceous, annular patches without scale or erosion that are limited to his right axilla (Figure, A).

No other lesions were noted on his skin or mucous membranes. A Wood lamp examination was negative. A punch biopsy specimen from a lesion was obtained (Figure, B and C).

Histopathologic examination revealed a lichenoid infiltrate of lymphocytes obscuring the dermal-epidermal junction. The lymphocytes are associated with saw-toothed epidermal hyperplasia, hypergranulosis, hyperorthokeratosis, and the presence of necrotic keratinocytes, all of which are features consistent with lichen planus.

With the distribution occurring in an intertriginous area, the diagnosis of inverse lichen planus was made.

On the basis of these findings, triamcinolone acetonide cream, 0.1%, twice daily for 3 weeks was prescribed. The patient returned 5 months later with resolution of his right-axilla lesions but with new onset of similar lesions in his left axilla and bilateral inguinal folds. Laboratory workup for hepatitis C was negative.

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