Which congenital pigmented nevus carries the greatest concern for malignant transformation?

Which congenital pigmented nevus carries the greatest concern for malignant transformation?

• A. Junctional nevus
• B. Dermal nevus
• C. Small pigmented nevus
• D. Giant congenital nevus

Answer: (D)

The key idea is that the risk of malignant transformation in congenital pigmented nevi increases with size and extent. Giant congenital nevi are present at birth and cover a large body area, containing many nevus cells spread through the skin (and sometimes deeper tissues). This abundance and depth of melanocytic tissue create more opportunities for genetic changes that can lead to melanoma over time, so they carry the greatest concern for malignant transformation compared with smaller or non-congenital types. In contrast, junctional nevi are flat lesions at the epidermal-dermal junction and, while they can transform, do so far less frequently. Dermal nevi are usually intradermal and often remain stable with a lower melanoma risk. Small pigmented nevi are common and typically pose the least risk of malignant change among the options.

The key idea is that the risk of malignant transformation in congenital pigmented nevi increases with size and extent. Giant congenital nevi are present at birth and cover a large body area, containing many nevus cells spread through the skin (and sometimes deeper tissues). This abundance and depth of melanocytic tissue create more opportunities for genetic changes that can lead to melanoma over time, so they carry the greatest concern for malignant transformation compared with smaller or non-congenital types.

In contrast, junctional nevi are flat lesions at the epidermal-dermal junction and, while they can transform, do so far less frequently. Dermal nevi are usually intradermal and often remain stable with a lower melanoma risk. Small pigmented nevi are common and typically pose the least risk of malignant change among the options.