Last updated: January 2024
Also known as: Becker’s melanosis
What is Becker’s naevus?
Becker’s naevus is a birthmark that appears as a flat brown discolouration in which darker thicker hairs may later grow. It is usually located on the shoulder, chest or back.
Who gets Becker’s naevus?
Becker’s naevus occurs most commonly in males. It usually appears in adolescence or in the twenties.
What causes Becker’s naevus?
Becker’s naevus is a developmental abnormality in which there is an overgrowth of some tissue types. It can be triggered by circulating androgens, such as testosterone.
Becker’s naevus is not an inherited disorder and is not passed onto the next generation.
What does Becker’s naevus look like?
Becker’s naevus starts as a large area of more pigmented, but otherwise normal skin.
It is mostly seen on the trunk, particularly the shoulder or chest, but can also be seen on the legs or arms.
After puberty, there is an increased growth of hair that slowly becomes thicker and darker.
In some cases, the pigmentation change is absent and only the hairs are seen. The skin may feel thicker if the deeper skin muscle fibres are present in greater than normal amounts.
How is Becker’s naevus diagnosed?
The diagnosis is usually made clinically.
In some cases, a biopsy may be required to differentiate a Becker’s naevus from a café au lait macule which is usually present at birth or develops within the first year of life.
How is Becker’s naevus treated?
Treatment options will vary depending on the individual and their needs.
While there is no effective treatment for the majority of Becker’s naevus, there are some treatment options available to minimise the appearance and treat complications including:
- Pigmentation may be improved by the use of camouflage make-up. Pigment laser treatments can also be used to reduce the pigmentation, but have not been very successful and may worsen the pigmentation.
- Hair removal on a Becker’s naevus may be conducted using waxing, shaving, threading, and epilation creams. These methods will not increase the hair growth on the naevus.
- The excess hair may be reduced with laser treatment. Multiple treatments are needed.
What is the likely outcome of Becker’s naevus?
Although an instance of Becker’s naevus cannot be removed entirely, the cosmetic appearance can be improved. There is currently no evidence that Becker’s naevus can become malignant.