• The Journal of the Korean bone and joint tumor society
• /
• v.15 no.1
• /
• pp.65-68
• /
• 2009

Proliferating trichilemmal tumor(PTT) is a rare neoplasm derived from the outer root sheath of the hair follicle. Malignant transformation is rare, but abrupt enlargement of size, infiltrative growth, and non-scalp location are suggestive of malignant PTT. Histopathologic characteristics of malignant PTT are nuclear atypia, pleomorphism, and mitotic figures. Recurrence and metastasis have been documented in malignant PTT. Wide resection of the tumor with the normal tissue and accurate follow-up is the treatment of choice of the both malignant and benign PTT. We report a 51-year-old man with the mass on right 5th finger distal phalanx for 7 years. The tumor was excised with middle phalangiectomy, and based on the histopathologic findings of the tumor, this case was diagnosed as mailignant PTT. We cannot detect recurrence and metastasis because the patient was lost to follow-up.