Last updated: February 2024
What is epidermal naevus?
Epidermal naevus is a term for a group of birthmarks made from cells from the outer portion of the skin (the epidermis), which appear in one or many lines or in a swirled pattern.
Who gets epidermal naevus?
Epidermal naevi most commonly occur in the first year of life. However, they can present at birth or develop throughout childhood.
What causes epidermal naevus?
Epidermal naevi occur when early in the life of the embryo a genetic mutation develops in one cell, which divides and populates the cells along a line of development (Blaschko’s lines). This mutation is not found in other cells of the body.
To date mutations have been found in HRAS, KRAS, PIKC3A, FGFR (fibroblast growth factor 2 and 3), KRT1 and KRT10 (keratin) when the skin is sampled. However, skin biopsy is not the usual way for making the diagnosis.
What does epidermal naevus look like?
Epidermal naevi can have a dark, rough or warty texture (verrucous EN) or a yellow bumpy appearance (naevus sebaceous) or may look like a swirl or line of blackheads (naevus comidonicus) or can even be red and scaly (inflammatory linear verrucous epidermal naevus ILVEN). Becker’s naevus usually appears on the trunk of an older child with a raised, brown and hairy patch.
Figure 1. © 2021 Elsevier Inc. All rights reserved. Habif’s Clinical Dermatology. A Color Guide to Diagnosis and Therapy. SEVENTH EDITION James G.H. Dinulos, MD
How is epidermal naevus diagnosed?
The diagnosis is usually made by a dermatologist or a paediatrician who has seen the child and recognises the appearance of the lesion(s).
How is epidermal naevus treated?
Treatment options will vary depending on the individual and their needs.
Small lesions can be surgically excised. Larger lesions should be discussed with a dermatologist and/or plastic surgeon.
What is the likely outcome of epidermal naevus?
Most epidermal naevi remain unchanged in adulthood and do not cause any further complications.
| Professor Orli Wargon, Dr Davin Lim and Dr Heba Jibreal | February 2024 |
| Professor Orli Wargon, Dr Davin Lim and Dr Heba Jibreal | August 2015 |