Skin nonmelanocytic tumors
Adnexal tumors - hair follicles
Pilar tumor

Author: Christopher Hale, M.D. (see Authors page)

Revised: 5 September 2018, last major update June 2012

Copyright: (c) 2002-2018,, Inc.

PubMed Search: Pilar tumor

Cite this page: Hale, C. Pilar tumor. website. Accessed October 20th, 2018.
Definition / general
  • Also called proliferating trichilemmal cyst
  • Neoplastic version of trichilemmal cyst
  • Women > men, base of neck and scalp
  • Usually benign, may recur locally, metastases are very rare and seen only with obvious malignant cytologic features resembling a focal trichilemmal carcinoma or a sarcomatoid carcinoma
Case reports
Clinical images

Images hosted on other servers:

Pilar tumor

Gross description
  • Pure tumors are multinodular, may be huge
  • May coexist with trichilemmal cyst
Microscopic (histologic) description
  • Solid with pushing borders and lobulated contour, usually involves epidermis but may open into skin surface
  • Bands of squamous epithelium with trichilemmal-type keratinization
  • May have prominent atypia, focal stromal invasion
Microscopic (histologic) images

Images hosted on other servers:

Various images

Molecular / cytogenetics description
  • Nondiploid DNA