Nevi

Nevi, commonly known as moles, are benign skin lesions formed by clusters of nevus cells derived from melanocytes. They typically appear in childhood or adolescence and may darken or enlarge before stabilizing. Nevi vary in color from tan to brown or black and can be flat (macular) or raised (papular). They are usually well defined and symmetric.

Histologically, nevi are classified by the location of nevus cells: junctional nevi (at the dermal-epidermal junction), compound nevi (both at the junction and in the dermis), and intradermal nevi (within the dermis). Clinically, they may appear round or oval, with uniform color and borders.

Most nevi are harmless and do not require treatment. They can change over time, and any new or evolving lesion should be evaluated by a clinician to exclude melanoma. Individuals with many nevi or with dysplastic (atypical) nevi have a higher risk of melanoma, particularly in the context of genetic predispositions such as familial atypical multiple mole melanoma (FAMMM) syndrome.

Management generally involves observation and sun protection. Regular skin self-examination using the ABCDE criteria—Asymmetry, Border irregularity, Color variation, Diameter over 6 mm, and Evolution—helps identify changes that warrant professional assessment. Removal is performed for diagnostic purposes or cosmetic reasons, or if a lesion appears suspicious; methods include shave, punch, or excisional biopsy.

Prognosis is favorable for typical nevi, as most remain benign. Malignant transformation is uncommon but early detection of suspicious changes is important for effective treatment.