D Sarma, E Santos
benign adnexal tumor, desmoplastic trichilemmoma, trichilemmoma
D Sarma, E Santos. Desmoplastic Trichilemmoma. The Internet Journal of Dermatology. 2008 Volume 7 Number 2.
The following microscopic pictures are from an excised 0.8 cm skin-colored nodule of the upper lip of a 49-year-old man. The lesion has been present for an unknown period of time.
Diagnosis: Desmoplastic tricholemmoma.
The purpose of this brief communication is to alert pathologists to the histologic features associated with a rare variant of trichilemmoma, which may easily be mistaken for carcinoma of the skin or adnexa.
Desmoplastic trichilemmoma is a rare trichilemmoma variant arising from the outer root sheath or infundibular epithelium and occurring predominately on the face of affected individuals. The patient commonly presents with a slow-growing, solitary, dome-shaped papule. Simple excision of the lesion is the treatment of choice and is curative. There is no association of the lesion with Cowden’s disease.
Histologically, desmoplastic trichilemmoma shows a biphasic pattern of usual trichilemmal cell lobules at the periphery with a central or sometimes peripheral sclerotic/hyalinized area, containing small epithelial cells with an “infiltrative” appearance. These morphologic features may be misinterpreted as trichilemmal carcinoma, squamous cell carcinoma, sclerosing basal cell carcinoma, and/or basosquamous cell carcinoma.