MELANOCYTIC LESIONS IN A PRIVATE PATHOLOGY PRACTICE - COMPARISON OF HISTOLOGIC FEATURES IN DIFFERENT TUMOR TYPES WITH PARTICULAR REFERENCE TO DYSPLASTIC NEVI

This study reviews a total of 1000 melanocytic lesions - two separate 500 consecutive sample groupings from 1980 and 1989, respectively - di agnosed in a private non-hospital-associated pathology practice. Lesio ns were classified as lentigo simplex, congenital nevus, ''common'' ne vus, dysplastic nevus, blue nevus, Spitz's nevus or malignant melanoma . A comparison of the two periods reveals an increase in dysplastic ne vi from one in 1980 to nine in 1989. The histologic changes in these n evi were compared to those of the other tumors. Pronounced cytologic a typia was seen in the melanocytes of a few ''common'' nevi, but more o ften in the dysplastic nevi and in all of the melanomas. Slight nuclea r atypia was usual in ''common'' nevi and lentigines, and also fibropl asia, lymphocytic infiltration, vessel proliferation and pigment incon tinence were seen in both ''common'' nevi and dysplastic nevi. It is c oncluded that no single histologic variable was specific for dysplasti c nevi.