Dermoscopic Patterns of Nevi and Melanoma Differentiation

Conclusions

• Dermoscopy can distinguish benign from malignant melanocytic lesions by evaluating global pattern, symmetry, organization, color count, and specific local structures.
• Benign nevi usually show ordered, symmetric, and recurrent patterns such as reticular, globular, homogeneous blue, or mixed but symmetric multicomponent patterns.
• Melanoma is more likely when a lesion is asymmetric, disorganized, multicolored, and shows atypical structures such as off-center blotches, irregular dots and globules, atypical network, or regression features.
• The meaning of a dermoscopic feature depends on context, because some signs can occur in both benign and malignant lesions but are concerning when focal, asymmetric, or combined with other warning signs.
• Patient age, skin type, and anatomic location strongly influence the expected dermoscopic pattern of nevi, so interpretation must be adjusted to clinical context.
• Congenital nevi and nevi with congenital-like features commonly show globular, cobblestone, reticular-globular, diffuse, or multicomponent patterns with hairs, perifollicular changes, or milia-like cysts.
• Acquired melanocytic nevi more often show reticular or reticular-homogeneous patterns and can evolve with age toward more reticular appearances.
• Blue nevi are characteristically homogeneous blue lesions, usually with a global pattern of homogeneous pigmentation and little structural complexity.
• Intradermal nevi often appear as homogeneous globular, pink-tan, or cobblestone lesions with comma vessels and may mimic other benign tumors.
• Spitz/Reed nevi commonly show a starburst pattern with symmetric radial streaming or pseudopods, but atypical or traumatized lesions can resemble melanoma and may require excision.
• Pink lesions often have few pigment structures, so vessel morphology becomes especially important for diagnosis, with benign lesions tending to have uniform comma-type vessels and melanoma tending to show polymorphous or irregular vessels.
• When a lesion displays melanoma-specific dermoscopic features or a pattern that strongly simulates melanoma, biopsy or complete excision is often warranted rather than simple observation.