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Dysplastic nevi: causes, symptoms, diagnosis, treatment
Last reviewed: 07.07.2025
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Dysplastic nevi (syn. Clark's nevi) are a variant of acquired melanocytic nevi that are characterized by an increased risk of malignancy due to the preservation of the proliferative activity of immature melanocytes in the epidermis and cell atypia of varying severity. Clinically, they resemble common pigment nevi, differing in their larger size (6-12 mm on average), irregular, often bizarre, star-shaped outlines, with uneven coloring varying from light brown to black. Dysplastic nevi are flat or slightly elevated in the center above the skin level, they always have a spotted component. In the presence of a central papular component, dysplastic melanocytic nevi are compared in appearance to "fried eggs". Their number varies: from single to a hundred or more, scattered throughout the skin, with a preferred localization on the upper half of the body.
Pathomorphology. Borderline or mixed melanocytic nevi with signs of atypia of individual melanocytes in the epidermis in the dermal-epidermal border zone are revealed. The degree of dysplasia (mild, moderate, severe) is determined depending on the size of the nevomelanocyte nuclei (smaller or larger than the size of the nuclei of the keratinocytes of the spinous layer), the presence of variability in the outlines and sizes of the nuclei, the characteristics of chromatin and the nucleolus. In addition to dysplasia itself, lentiginous melanocytic hyperplasia and uneven distribution of melanocyte nests in the epidermis along the dermal-epidermal border, their fusion with each other, as well as the formation of bridges between adjacent epidermal outgrowths are characteristic. In sour cream nevi, the epidermal component is longer than the dermal one and occupies at least three epidermal outgrowths along the periphery of the neoplasm. Signs of dysplastic nevi also include the presence of perivascular lymphoid infiltrates and fibrous changes in the papillary layer of the dermis (concentric or lamellar eosinophilic fibroplasia).
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