Skin nonmelanocytic tumor
Cysts
Proliferating pilar tumor
Author: Christopher S. Hale, M.D.
Topic Completed: 1 June 2012
Minor changes: 17 January 2022
Copyright: 2002-2022, PathologyOutlines.com, Inc.
PubMed Search: Pilar tumor
Table of Contents
Definition / general | 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 January 21st, 2022.
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
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:
Trichilemmal type keratinization
Molecular / cytogenetics description
- Nondiploid DNA
Differential diagnosis
