Giant hair matrix tumor

Twelve cases of a peculiar, relatively uncommon, benign but locally invasive tumor occurring in the skin of the scalp and mocha are reported. The neoplasm occurs primarily in elderly women and only exceptionally in men. Its growth is very slow and usually many years elapse before the patient comes under treatment; thus, the tumor may attain a huge size. These deeply invasive neoplasms do not metastasize but may recur if not completely excised. Morphologically, it is an epithelial keratinizing growth clearly showing differentiation into the pilosebaceous structures, especially into the outer sheath of the hair follicle. It does not correspond to the “pilomatrixoma” of Forbes and Helwig (calcifying epithelioma of Malherbe) and constitutes a distinct clinicopathologic entity.