From the Guidelines
The percentage of mildly and moderately dysplastic nevi that transform into melanoma is estimated to be very low, with no occurrences of melanoma reported in a study of 195 dysplastic nevi with mild to moderate atypia over a 2-year follow-up 1. This suggests that the risk of transformation is minimal, and most dysplastic nevi remain stable throughout a person's lifetime.
- The risk of transformation may increase slightly with the degree of dysplasia, but the data from the study by Kmetz et al. as mentioned in 1 shows no progression to melanoma in patients with biopsy-proven atypical nevi, even with involved biopsy margins.
- Individuals with multiple dysplastic nevi are considered to be at higher risk of developing melanoma, but this risk is more related to the overall increased susceptibility rather than the direct transformation of existing nevi.
- Regular skin examinations are crucial for patients with dysplastic nevi, typically every 6-12 months, depending on risk factors such as personal or family history of melanoma, number of nevi, and severity of dysplasia, as recommended by general clinical guidelines and supported by the findings in 1.
- Any changing nevi should be evaluated promptly, as change can signal malignant transformation, highlighting the importance of vigilant monitoring over prophylactic removal of all mildly or moderately dysplastic nevi.
From the Research
Dysplastic Naevus and Melanoma Risk
- The exact percentage of mildly and moderately dysplastic naevus that turn into melanoma is not explicitly stated in the provided studies 2, 3, 4, 5, 6.
- However, it is established that dysplastic naevi are a risk factor for melanoma, with studies suggesting that they are associated with an increased risk of developing melanoma 3, 5, 6.
- A study published in 2006 found that individuals with naevi having greater than mild histological dysplasia had an increased risk of melanoma, with an odds ratio of 2.60 5.
- Another study published in 2013 noted that dysplastic nevi are important due to their association with an increased risk for melanoma, although the transformation of any individual nevus to a melanoma is rare 6.
Classification and Diagnosis of Dysplastic Naevus
- The classification and diagnosis of dysplastic naevus can be complex, with different studies using varying criteria to define these lesions 3, 4, 5.
- A study published in 1997 defined clinically atypical naevi as those meeting three of the following five criteria: > or = 5 mm in diameter, vaguely bordered, asymmetrically shaped, irregularly pigmented, and a red hue (erythema) 3.
- Digital dermoscopy analysis has been used to distinguish between dysplastic naevi and in situ melanomas, although the results have been inconsistent 4.
Risk Assessment and Management
- The risk of melanoma associated with dysplastic naevi is not fully understood, and further studies are needed to establish reproducible and predictive criteria for grading naevi 5.
- Individuals with a family history of melanoma and dysplastic naevi may be at increased risk of developing melanoma, and regular skin examinations and monitoring may be necessary 3, 6.