Skin nonmelanocytic tumor
Adnexal tumors
Hair follicles
Hair follicle nevus
Author: Hillary Rose Elwood, M.D.
Last author update: 1 June 2016
Last staff update: 16 October 2020
Copyright: 2001-2024, PathologyOutlines.com, Inc.
PubMed search: hair follicle nevus
Table of Contents
Definition / general | Clinical features | Case reports | Microscopic (histologic) description | Differential diagnosisCite this page: Elwood HR. Hair follicle nevus. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/skintumornonmelanocytichairfolliclenevus.html. Accessed December 19th, 2024.
Definition / general
- Rare, congenital, hamartomatous proliferation of mature vellus hairs
- Also known as congenital vellus hamartoma
Clinical features
- Usually present at birth or early childhood
- Solitary skin colored papule, less than 1 cm in greatest dimension
- Sometimes with hypertrichosis
- Most commonly on head and neck
- Rarely multiple or arranged in a linear distribution, following the lines of Blaschko (J Am Acad Dermatol 2002;46:S125)
Case reports
- 2 year old boy with nose nodule (Pediatr Dermatol 2008;25:60)
- 26 year old man with small soft nodules on his nose since childhood (Eur J Dermatol 2008;18:185)
- Hair follicle nevus with features of comedo nevus (Am J Dermatopathol 2016;38:e81)
Microscopic (histologic) description
- Increased numbers of closely situated mature vellus hair follicles
- Some are associated with small sebaceous glands or have thickened perifollicular fibrous sheaths
- Follicles may be located abnormally high within the dermis
- No cartilage (seen in accessory tragus), central cysts or a central canal (seen in trichofolliculoma)
Differential diagnosis
- Accessory tragus: also has increased vellus hairs, but usually has other types of tissue (i.e. mature adipose tissue or cartilage); location around the ear is also helpful
- Trichofolliculoma: has central cyst or canal; deeper levels may be necessary to find trichofolliculoma in a lesion that resembles hair follicle nevus
