Malignant proliferating trichilemmal tumor.

Proliferating trichilemmal tumors are uncommon neoplasms that are usually benign, but characterized by frequent local recurrence. In this report, we describe a patient who sought treatment at our clinic for a right occiput scalp nodule measuring 1 cm in diameter. The subcutaneous lesion was mobile and without overlying skin ulceration. Excisional biopsy of the mass was performed and the pathologic diagnosis returned as malignant, proliferating trichilemmal (pilar) tumor. Resection margins were free of tumor. On further examination the patient had no evidence of metastatic disease. A schedule of routine follow-up visits was arranged to monitor the site for recurrent disease.