Congenital melanocytic naevus

Created: 19th February 2012 | Last Updated: 24th April 2017

Acknowledgements: to Dr Veronica Kinsler (Clinical Fellow, Paediatric Dermatology Dept, Great Ormond St Hospital for Children NHS Trust, Great Ormond St, London) for helping develop this chapter and for providing images 7-10.

Introduction

Approximately 1% of newborns have congenital melanocytic naevi (CMN) and they are usually present at birth.

This chapter is set out as follows:

Clinical findings
Images
Management
Other resources

Related chapters

Melanocytic naevi

Clinical findings

Lesions tend to be larger in size than acquired naevi and are dark brown or black in colour with deeper extension of melanocytes into the dermis and surrounding appendages
The size can vary from small to very large
Lesions projected to be > 20 cm diameter in adulthood are termed giant congenital naevi
Congenital naevi often become protuberant and hairy
Satellite lesions - these are additional melanocytic lesions in the skin, some of which may be distant to the main CMN

Images

Please click on images to enlarge, or choose to download. Images must only be used for teaching purposes and are not for commercial use. Notice and credit must be given to the PCDS and any other named contributor.

Download	Figure: 1 Congenital melanocytic naevus of the shoulder
Download	Figure: 2 Congenital melanocytic naevus of the thigh
Download	Figure: 3 Congenital melanocytic naevus of the abdomen
Download	Figure: 4 Congenital melanocytic naevus
Download	Figure: 5 Dermoscopic appearance of figure 4 Congenital melanocytic naevi have a number of different dermoscopic appearances. This one has regular areas of hyperpigmentation (blue arrows)
Download	Figure: 6 Giant congenital melanocytic naevus Satellite lesions present on buttocks Copied with kind permission from Dermatoweb
Download	Figure: 7 Giant congenital melanocytic naevus
Download	Figure: 8 Same patient as figure 7 Satellite lesions on lower legs
Download	Figure: 9 Same patient as figure 7 Satellite lesions on arms
Download	Figure: 10 Close-up of figure 7

Management

Complications

Neurocutaneous melanosis
- The main complications of CMN result from the presence of melanin in the CNS (neurocutaneous melanosis)
- Although some patients remain asymptomatic, complications include developmental delay, fits and melanoma
- The likelihood of having neurocutaneous melanosis correlates most strongly with the size of the CMN, and with the presence of satellite lesions - the finding of other melanocytic lesions in the skin, some of which may be distant to the main CMN. The site of CMN does not appear to be relevant
- Current recommendations are that patients should have an urgent MRI if they have any clinical features of neurological complications. Whether or not asymptomatic patients with satellite lesions should be scanned early in life is debatable

Melanoma
- The main risk for the development of melanoma is in patients with giant melanocytic naevi, who require long-term follow up by a dermatologist. The risk for patients with small / moderate sized lesions is very low

Surgical management of CMN

Current recommendations from Great Ormond Street Hospital are that most CMN should not have routine surgical treatment. This decision requires substantial support of the family and patient and good explanation of the reasons for this, which are as follows:
- Surgery should not be considered to be prophylactic for melanoma because a) superficial partial removal (dermabrasion or laser) does not remove the whole lesion b) complete excision is not possible in the group at highest risk of melanoma (giant congenital melanocytic naevi), and other groups have an extremely low risk c) melanoma can arise outside the CMN, either in a different area of skin or within the CNS
- Most CMN will become lighter spontaneously over the first few years at least, and occasionally this is very dramatic. Serial photographs of CMN should be taken to assess lightening, as both families and physicians can fail to notice this gradual process
- There are some concerns that surgical treatment of the lesions may adversely affect the spontaneous lightening process and the behaviour of the melanocytes in the CMN, although further research needs to be done in this area
Surgical removal for cosmetic reasons does have a place in the management of CMN, particularly for facial lesions, however:
- There is no controlled evidence to support the belief that superficial removal techniques (dermabrasion or laser) need to be performed as early as possible
- There are also concerns about possible adverse effects of early surgery, especially under the age of one year. There is some evidence from other specialties that the use of general anaesthesia in this age group may increase the risk of neurological complications such as cognitive impairment

Other resources

Patient support group for CMN - Caring Matters Now
There is a weekly dedicated clinic for CMN and their pigmentary abnormalities at the Great Ormond Street Hospital