What is a Congenital Melanocytic Nevus?
Giant Congenital Melanocytic Nevi Background
- Compiled by Dr Dagmar Whitaker
President of the Melanoma Advisory Board South Africa
Vice President of the Melanoma World Society
Congenital Melanocytic Nevi (CMN) are defined as visible melanocytic proliferations present at birth. They can be light brown to black patches or plaques and can vary in size from a few mm to covering nearly any surface area or a part of the body. The incidence of CMN is independent of skin colour and ethnic factors. Small to medium sized CMN occur in more than 1 in 100 births. Large or giant CN (GCMN) exceeding a predicted diameter at adult age of at least 20cm has estimated incidents of 1 in 500 000 births (Price and Schaffer, 2010).
5 - 15 % of larger CMN can be complicated by Neurocutaneous nevomelanocytosis (NM), abnormal aggregation of nevomelanocytes in the central nervous system. Melanoma develops in 1 - 2% of patients with large or giant CNM and it occurs in earlier ages than the general population (Krengel et al 2006, Schaffer 2010). Half of the melanomas occur in the first five years of life. The melanomas tend to arise deep in the skin or even in residual fatty tissue making detection sometimes difficult.
Giant CMN happen sporadically, and familiar occurrence has only rarely been reported. GCMN are diagnosed clinically and an MRI of the brain and spine is recommended to exclude NM. Lifelong monitoring in patients with extensive GCMN is mandatory both with self-examination and follow-up with a dermatologist. Digital dermoscopy together with clinical examinatic (palpation) aids in diagnosing early stages of Melanoma; suspicious areas should be removed. Surgical removal sometimes with forced expansion is recommended wherever accessible. On-going surveillance is an option for extensive, technically inaccessible nevi.
Psychological accompaniment is highly recommended for both patients and families. The psychological burden relating to disfigurement and self-image problems is significant. Lifestyle coaching is mandatory from an early age onwards. Patient advocacy groups play an important role to lessen the burden of living with a visible, cosmetically challenging, skin condition. Children can feel they are not alone and so can their parents.
The Nevus Association South Africa is a step towards helping and supporting children with GCMN and their families, to learn more about their disease and to help them understand it better and improve their lives through sharing. It is an initiative started in collaboration with the Melanoma Society and an
interested and active parent body supported by Galderma.