Cranial vault tumor: malignant proliferating trichilemmal tumor of the scalp

Proliferating trichilemmal tumor (PTT) is a rare cutaneous tumor that mainly occurs in the scalp, eyelids, neck, and face of elderly women. In most cases, it is a unique, large, multi-lobulated, cystic lesion originating from a hair follicle. These tumors are mostly benign and are characterized by trichilemmal keratinization. However, in rare cases, they may be aggressive with a propensity for distant metastasis. We report the case of a 69-year-old male patient, who presented with as welling on his forehead that had rapidly increased in size over the past year. CT scan and magnetic resonance imaging (MRI) showed a tumor located on the cranial vault, associated with an intracranial extension. Chest X-ray and CT scan found a tumor in the right lung. The patient underwent surgery for the removal of the tumor. The histological examination confirmed the diagnosis of malignant PTT (MPTT). To the best of our knowledge, only a few cases of MPTT have been published. Furthermore, only one case of MPTT of the scalp with endocranial extension and lung metastasis has been eported to date. Through this case, we discuss the prognostic factors and the management of this aggressive lesion.