Proliferating trichilemmal cyst (PTC) is a rare but morphologically distinctive tumor that usually occurs in the scalp of elderly women. Furthermore, only 30 well-documented examples of so-called malignant PTC have been reported. Alternatively, some authors have recently proposed that PTC is squamous cell carcinoma. We describe a case of PTC with focal invasion that was indistinguishable from squamous cell carcinoma in areas, and we review the literature. This debate should be considered in PTCs to provide adequate treatment (wide local excision) and follow-up (long term), particularly in large and long-standing lesions.
From the Departments of Pathology (F.L.-R., L.H.) and Dermatology (A.A., M.G.), Severo Ochoa Hospital, and the Department of Pathology (J.L.R.-P.), 12 de Octubre Hospital, Madrid, Spain.
Results of this study were presented in part at the 19th Colloquium of the International Society of Dermatopathology, November 1998, Madrid, Spain.
Address correspondence and reprint requests to José Luis Rodríguez-Peralto, M.D., Hospital Universitario 12 de Octubre, Departamento de Anatomía Patológica, Carretera de Andalucía km 5.4, 28041 Madrid, Spain.