Trichomycosis Axillaris
A 35-year-old man presented to the dermatology clinic with a 9-month history of white clumps on the hairs of his axillae. He had initially noticed the deposits on the hair of his axillae and groin. The pubic-hair involvement resolved after an episode of shaving, but the abnormalities with regard to the axillary hair persisted despite regular washing with coconut-oil–based and antibacterial soaps and one episode of shaving. He reported no malodor, pain, or pruritus. On examination, white concretions encircling the hairs in both axillae (Panel A) were observed. A Wood’s lamp examination showed yellow-green fluorescence of the concretions (Panel B), and dermoscopy revealed cottonlike structures on the hair shafts (Panel C). A diagnosis of trichomycosis axillaris was made. Trichomycosis axillaris is a superficial bacterial infection of the hair of the axillae; the name is a misnomer, given that it is caused by corynebacterium species as opposed to fungi. Visible deposits form on hair shafts when bacteria mix with dried apocrine sweat, especially in the presence of hyperhidrosis or impaired hygiene. After 1 week of treatment with topical clindamycin and a daily benzoyl peroxide wash, the patient’s symptoms abated and did not recur.
