Age distribution and histologic patterns of dysplastic nevi.

A total of 676 dysplastic moles collected from 487 patients over a 1-year period were reviewed together with demographic data. The associated nevus in 642 cases (95%) had a superficial, or "acquired," pattern within the papillary dermis, in comparison with the nevus in the remaining 34 cases (5%), which showed a deep, or "congenital," pattern. The dysplasia was graded in severity as mild, moderate, or severe (on a scale of 1 to 3). When patients with mild to severe dysplastic melanocytic nevi were compared with those patients showing atypical intraepidermal melanocytic hyperplasia (also called in situ malignant melanoma) or early invasive malignant melanoma associated with dysplasia, a progression of ages was noted. The average ages in the five diagnostic groups were as follows: 34.8 years, mild dysplasia (group 1); 35.1 years, moderate dysplasia (group 2); 41.5 years, severe dysplasia (group 3); 44.4 years, in situ malignant melanoma (group 4), and 46.9 years, early invasive malignant melanoma (group 5). Statistical analysis revealed that the two younger groups differed significantly in age from the three older groups. Men and women had an equal proportion of acquired and congenital pattern nevi, but men were older in each category and had more severe dysplasia, a greater tendency toward truncal lesions, and more regressive changes. Biopsy of trunk lesions was done in 275 cases (80%), of extremity lesions in 60 cases (17%), and in head and neck sites in 9 cases (3%).(ABSTRACT TRUNCATED AT 250 WORDS)