Linear trichilemmomas on the ankle of a 28‐year‐old female

Abstract

Trichilemmomas are benign cutaneous proliferations derived from the outer root sheath of the hair follicle. They most often occur on the head and neck region and show a female predominance. When multiple, they are associated with Cowden syndrome (CS), a rare disorder due to an autosomal dominant germline mutation in PTEN (phosphatase and tensin homolog on chromosome 10), a tumor suppressor gene. Trichilemmomas outside of the head and neck region are rare, and as such, the association with CS is not clear. A 28-year-old healthy female with no significant family history of cancer presented to her dermatologist with multiple erythematous papules on the left anterior ankle, starting at birth. A shave biopsy confirmed the diagnosis of trichilemmoma with focal desmoplastic features (or desmoplastic trichilemmoma). A PTEN immunohistochemical study showed patchy (but not complete) loss of staining of the lesional cells. After shave removal, the trichilemmomas recurred 1-2 months later.

Linear trichilemmomas: An unusual clinical presentation

“…Linear pattern in blaschkoid distribution has also been reported previously on the nose 3 and ankle. 4 Lesions are usually skin colored, verrucous surfaced or smooth, small papular lesions which sometimes coalesce to form small plaques. Usual location is on the head-and-neck region of older individuals.…”

“…Visceral manifestations such as carcinomas of thyroid, breast and endometrium, macrocephaly, dysplastic cerebellar gangliocytomas and renal cell carcinomas have been reported. 4,5 Classical histopathology of trichilemmomas depicts wellcircumscribed lobular neoplasm connected to the epidermal or follicular epithelium at multiple points and comprising of pale to clear vacuolated cells centrally with peripheral cuboidal cells arranged in palisade and resting on a thick glassy basement membrane. Clear or pale cells contain glycogen.…”