Skin nonmelanocytic tumor
Adnexal tumors
Hair follicles
Proliferating pilar tumor
Author: Christopher S. Hale, M.D.
Topic Completed: 1 June 2012
Minor changes: 16 October 2020
Copyright: 2002-2020, PathologyOutlines.com, Inc.
PubMed Search: Pilar tumor
Table of Contents
Definition / general | Case reports | Clinical images | Gross description | Microscopic (histologic) description | Microscopic (histologic) images | Molecular / cytogenetics description | Differential diagnosisCite this page: Hale CS. Proliferating pilar tumor. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/skintumornonmelanocyticpilartumor.html. Accessed October 21st, 2020.
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
- 64 year old man with tumor on scalp (Dermatol Online J 2008;14;10:25)
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
Differential diagnosis
