Also known as … Comedonal naevus, Follicular keratotic naevus and Pilosebaceous naevoid disorder.
Naevus comedonicus is a rare type of epidermal nevus. A benign overgrowth derived from a hair follicle unit.
It is a condition that shows equal prevalence across all races and sexes. Although most cases arise sporadically, familial clustering has been reported.
While the exact cause is unknown, it is believed to be related to a genetic imbalance during the development of the skin, hair follicle sand sebaceous glands. A couple of particular genes, called Fibroblast Growth Factor Receptor 2 (FGFR2) and NIMA Related Kinase 9 (NEK9), has been implicated.
Naevus comedonicus usually develops shortly after birth or during childhood. It looks like a group or cluster of widely opened follicles with keratinous plugs inside them (Comedo-like). They can appear in various formations, which include in clusters, in a straight line, or along the skin fold lines (called a Blaschkoid pattern).
Naevus comedonicus aggregates mostly on the face, chest, and upper limbs. There is an inflammatory variant that is associated with cysts, pus filled bumps and abscess.
Rarely, extensive naevus comedonicus may be associated with:
- Neurological defect: brain abnormalities, seizures or developmental delay
- Musculoskeletal anomalies
At puberty, hormonal influences often worsen the condition with the appearance of inflamed lesions & cysts within the naevus.
The diagnosis is usually made clinically by a Dermatologist. A biopsy may be needed to support the diagnosis.
Naevus comedonicus does not require active or medical treatment. Mild improvement can be achieved using
- Topical retinoids
- Topical keratolytics
- Manual Comedo extraction
For disfiguring lesions, surgical excision or Laser therapy may be considered.
Naevus comedonicus persists throughout the individual’s life. Most patients will only seek treatment for cosmetic purposes.
This information has been written by Dr Ramez Barsoum and Dr Heba Jibreal
Wong. Published October 2020