Pilomatrixoma D23.L

A. Painted sherbet 1880

Frequent, mostly solitary, rarely multiple, benign adnexal tumor originating from the hair matrix cells and calcifying early with hair follicle differentiation.

Solitary, rarely multiple, painless, hard to bony, sharply defined, 0.5-3 cm in diameter (rarely larger - giant pilomatricoma), subcutaneous, skin-colored, reddened or reddish-brown nodule. Frequently calcifications, more rarely ossifications. Very slowly progressive, usually growing over several years.

Rare clinical variants are.

• anetodermic variant (skin over the tumor appears atrophic)
• pigmented pilomatrixoma
• ulcerated pilomatrixoma
• giant forms (up to 20 cm in size)
• multiple pilomatrixomas possibly in association with Turner syndrome, trisomy 9, Gardner syndrome
• multiple familial pilomatrixomas

Lobular tumor in the middle to deep dermis, in some places also extending into the subcutis. The appearance depends on age (regressive changes). Basophilic cells with hyperchromatic nuclei and some (sometimes numerous) mitoses are localized in the outer layer. Centrally, there are usually eosinophilic cells (shadow cells). Older tumors show extensive zones of necrosis and metaplastic calcifications. Regressive tumors are surrounded by dense granulation tissue.

Clinic is characteristic, histology is conclusive.

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