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Dysplastic nevi: causes, symptoms, diagnosis, treatment
Last reviewed: 23.04.2024
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Dysplastic nevuses (blue clark 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 atypism of cells of varying severity. Clinically reminiscent of ordinary pigment nevi, differing in larger sizes (on average 6-12 mm), irregular, often bizarre, stellate outlines, with uneven coloration, ranging from light brown to black. Dysplastic nevi are flat or slightly elevated in the center above the level of the skin, they always have a spotted component. In the presence of a central papular component, dysplastic melanocytic nevi are compared in appearance with "fried eggs". The number of them is different: from single to one hundred or more, scattered throughout the skin, with a preferred location on the upper half of the body.
Pathomorphology. Border or mixed melanocytic nevus with signs of atypism of individual melanocytes in the epidermis in the zone of the dermo-epiermal border are detected. The degree of severity of dysplasia (mild, moderate, severe) is determined depending on the size of nevomelanocyte nuclei (smaller or larger than the size of the keratinocyte nucleus of the spinous layer), the presence of variability in shape and size of nuclei, the characteristics of chromatin and the nucleolus. In addition to the actual dysplasia, lentiginous melanocytic hyperplasia and irregularity of the location of the nests of melanocytes in the epidermis along the dermo-epidermal border are characteristic, their fusion among themselves, as well as the formation of bridges between neighboring epidermal outgrowths. In the swallowed nevi, the epidermal component is longer than the dermal component and occupies not less than three zidermal processes along the periphery of the neoplasm. Signs of dysplastic nevi include the presence of perivascular lymphoid infiltrates and fibrotic changes in the papillary dermis (concentric or lamellar eosinophilic fibroplasia).
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