Rare Evolution of a Trichilemmal Cyst: A New Observation of Carcinomatous Degeneration

Abstract

The trichilemmal cyst, also called the hair cyst, is an infrequent adnexal tumor that derives from the isthmic portion of the hair follicle. It is an oftensolitary tumor with preferential localization of the scalp. Its evolution is generally benign. Malignant cases are very rare and sometimes aggressive. Only about fifty cases are reported in the literature. We report a new observation of carcinomatous degeneration illustrating the difficulty of the therapeutic management of this aggressive form. It was a 55-year-old patient with no significant pathological antecedents who, since 2012, has had voluminous and numerous scalp swelling, slow and indolent evolution. The management was surgical with excision of 13 cysts initially. Pathological examination showed an appearance consistent with proliferative trichilemma cysts without evidence of malignancy. The patient had a recurrence of cystic lesions after five years. She was reoperated with excision of three cysts whose histopathological examination showed a well-differentiated keratinizing squamous cell carcinoma developed on one of the cysts. We decided on a surgical revision with extensive excision of the tumor followed by recovery by a sliding flap and rotation. The evolution was favorable with a follow-up of two years. The main take away of our case is the locally aggressive character of this malignant form which necessitate an extensive surgical excision, thus posing the problem of reconstruction.