Nonpigmented dysplastic melanocytic nevi.

BACKGROUND

Dysplastic melanocytic nevi (DMN) are thought to represent a clinical and histologic bridge between common pigmented nevi and superficial spreading malignant melanoma. The following clinical criteria for DMN were established to aid in the proper identification of these lesions: irregular perimeter, size exceeding 5 mm in diameter, background erythema, and variegated color (shades of browns, tans, blacks, and reds). Histologic features include basilar melanocytic proliferation with nuclear atypia, a patchy lymphocytic infiltrate with concentric eosinophilic fibroplasia, and lamellar fibroplasia. To our knowledge, there have been no previously reported cases of uniformly nonpigmented DMN.

OBSERVATIONS: A 31-year-old brown-haired, browneyed white woman with no personal or family history of either DMN or melanoma presented for evaluation of numerous, discrete, nonindurated, 2- to 5-mm-diameter, nonpigmented macules and slightly elevated papules that had appeared in a truncal distribution over the course of several years. Microscopic examination of these lesions showed lentiginous epidermal hyperplasia and disordered proliferation with variable cellular atypia of intraepidermal melanocytes.

CONCLUSIONS

Nonpigmented, nonindurated, macular or slightly elevated papular lesions may represent nevi with features of dysplasia. In light of the significant risk of malignant melanoma that is associated with pigmented varieties of dysplastic nevi, it is essential that clinicians consider nonpigmented DMN in the differential diagnosis of entities that present as hypopigmented macules.