Recurrent proliferating trichilemmal cyst of the scalp.

Pilar tumors, commonly called trichilemmal cysts, are usually benign in nature, malignant transformation ( so called proliferating pilar tumors or proliferating trichilemmal cysts [PTCs]) with high recurrence rates, local invasion and metastases have been described. A 64-year-old women presented to our hospital with a recurrent ulcerated mass lesion of the scalp. Non-contrast-enhanced computed tomography scan of the head was performed. The mass was managed by complete excisional biopsy and the defect closure was achieved by using a full-thickness skin graft. Histopathological analysis revealed the characteristic structures of PTC; in addition foci of squamous pearls, squamous cells with pleomorphic nuclei suggestive of cellular atypia and increased typical mitotic activity were also noticed. PTCs are related to high recurrency rates, local invasion and possible metastases. Radical surgical treatment and precise histological analysis are essential in order to achieve a fast and complete healing. Cooperation of the clinician and the pathologist is essential for accurate diagnosis, treatment and follow-up planning.