From the Guidelines
Nevi (moles) can be hereditary, with certain types having a genetic component that can run in families. The tendency to develop multiple moles or specific types of nevi, such as dysplastic nevi (atypical moles), often has a hereditary basis, as noted in the 2016 study by the American Family Physician 1. Genetics influence melanocyte development and behavior, which determines mole formation. People with fair skin, light hair, and a family history of numerous moles are more likely to develop multiple nevi themselves.
Key Points to Consider
- A family history of melanoma is a significant risk factor, with individuals having three or more cases in their family requiring referral to a clinical geneticist or specialized dermatology services for counseling, as recommended in the 2010 guidelines by the British Journal of Dermatology 1.
- Those with two cases in the family may also benefit from counseling, especially if one of the cases had multiple primary melanomas or the atypical mole syndrome.
- Regular skin examinations by a dermatologist are crucial for individuals with a strong family history of atypical moles or melanoma, typically annually or more frequently if recommended.
- Environmental factors like sun exposure also play a significant role in nevus development, and understanding personal risk factors and appropriate screening schedules is essential.
Recommendations for Screening and Surveillance
- Patients who are at moderately increased risk of melanoma should be advised of this and taught how to self-examine, including those with atypical mole phenotype, previous melanoma, and organ transplant recipients, as stated in the 2010 guidelines by the British Journal of Dermatology 1.
- Individuals with giant congenital pigmented naevi are at increased risk of melanoma and require long-term follow-up.
- The prophylactic excision of small congenital naevi is not recommended, as noted in the 2002 guidelines by the British Journal of Dermatology 1.
From the Research
Hereditary Aspects of Nevus
- Nevus, particularly dysplastic nevus, has been linked to hereditary factors in the development of melanoma 2, 3, 4, 5
- Familial dysplastic nevus syndrome is an autosomal-dominant precursor of hereditary melanoma, characterized by distinctive nevi and an increased risk of melanoma 2
- Studies have shown that dysplastic nevi can be found in both familial and sporadic forms, with genetic features intermediate between common acquired nevi and melanoma 3
Genetic Inheritance of Nevus Characteristics
- Research has investigated the inheritance of nevus number and size in melanoma and dysplastic nevus syndrome kindreds, suggesting a possible mendelian pattern of inheritance for total nevus density (TND) 5
- A major gene may be responsible for 55% of the phenotypic variability of TND in multiplex kindreds, indicating a significant genetic component in the development of nevi 5
- The total number of nevi on an individual (TNN) and TND have been found to be increased in relatives of probands compared to spouse controls, further supporting the hereditary aspect of nevus development 5
Implications of Hereditary Nevus
- Recognition of dysplastic nevi offers an opportunity for analysis of pathogenetic mechanisms in cutaneous melanoma, and their removal can help exclude the possibility of melanoma 3, 4
- Patients with dysplastic nevi should adopt sensible patterns of skin care, and regular examination of nevi can help determine the risk of melanoma and minimize the potential for neoplastic progression 2, 4