label: Proliferating Trichilemmal Tumor
label_lc: proliferating trichilemmal tumor
description: A neoplasm with tricholemmal differentiation. It affects women more frequently than men. It usually presents on the scalp as a solitary, multilobular, large, exophytic mass. Morphologically, it may display benign cytological features and appear as a circumscribed solid-cystic neoplasm or it may display malignant characteristics and invasive features. Cases without malignant characteristics usually have an indolent course. Complete surgical excision is recommended in such cases to avoid recurrences and to allow complete examination of the specimen. Cases with malignant characteristics may have a locally aggressive clinical course, recur, or metastasize.