ABERRANT PATTERN OF LECTIN-BINDING IN LOW AND HIGH-GRADE PROSTATIC INTRAEPITHELIAL NEOPLASIA

Background. High grade prostatic intraepithelial neoplasia (PIN) is co nsidered a precursor lesion for peripheral prostatic adenocarcinoma. T he biologic significance of low grade PIN is unknown; however, the lik elihood of progression from low to high grade PIN has been suggested. Methods. A battery of nine lectins was applied to paraffin sections fr om 20 prostatectomies to identify prostatic carcinoma. The patterns of lectin binding were compared among normal/hyperplastic, dysplastic, a nd malignant glands. The increase in the Ki-67-defined growth fraction was compared with the lectin binding pattern. Results. An aberrant le ctin binding pattern, similar to that observed in adenocarcinoma, was observed in PIN for four of the lectins; this distinct staining patter n was found in glands with minimal dysplastic changes and in glands wi th high grade dysplasia. Specifically, staining for soy bean agglutini n and Ulex europaeus agglutinin was negative in benign and hyperplasti c glands and positive in dysplastic glands and carcinoma. Staining for wheat germ agglutinin and peanut agglutinin was weakly positive or ne gative in normal and hyperplastic glands, whereas it was strongly posi tive in dysplasia and carcinoma. The staining for Concavalin A, Ricinu s communis agglutinin, Dolichos biflorus agglutinin, and Lens culinari s agglutinin showed no difference between normal/hyperplastic and dysp lastic glands. The aberrant lectin binding already was evident in low grade dysplasia versus the increased Ki-67 defined-growth fraction tha t was obvious only in high grade dysplasia and carcinoma. Conclusions. These findings suggest that the early dysplastic lesions in the prost ate may be part of a continuum in the multistep process leading to inv asive carcinoma.