Frequency of dysplastic nevi among nevomelanocytic lesions submitted for histopathologic examination. Time trends over a 37-year period

All cutaneous nevomelanocytic specimens accessioned for histopathologic examination at Massachusetts General Hospital, Boston, in 1950, 1960, 1970, and 1987 were reviewed. The specimens were categorized as malignant melanoma, acquired or congenital benign nevi, blue nevi, spindle and epithelioid cell nevi, and dysplastic nevi. Other processes such as lentigines were excluded. There was a threefold increase in percentage of patients having nevomelanocytic lesions removed (1.5% in 1950 to 4.6% in 1987) compared with total surgical cases over the 37-year period. A progressive increase in numbers and percentages of dysplastic nevi (among nevomelanocytic surgical cases) was noted over a 37-year interval--2 cases (1% of nevomelanocytic cases) in 1950, 4 cases (2%) in 1960, 23 cases (5%) in 1970, and 189 cases (12%) in 1987. These findings confirm the existence of dysplastic nevi by histopathologic criteria as early as 1950 and illustrate the frequencies of various nevomelanocytic surgical specimens among all surgical specimens at four points in time over a 37-year period at a major referral center for pigmented lesions.