Aberrant pattern of lectin binding in low and high grade prostatic intraepithelial neoplasia

High grade prostatic intraepithelial neoplasia (PIN) is considered a precursor lesion for peripheral prostatic adenocarcinoma. The biologic significance of low grade PIN is unknown; however, the likelihood of progression from low to high grade PIN has been suggested.

A battery of nine lectins was applied to paraffin sections from 20 prostatectomies to identify prostatic carcinoma. The patterns of lectin binding were compared among normal/hyperplastic, dysplastic, and malignant glands. The increase in the Ki-67-defined growth fraction was compared with the lectin binding pattern.

An aberrant lectin binding pattern, similar to that observed in adenocarcinoma, was observed in PIN for four of the lectins; this distinct staining pattern was found in glands with minimal dysplastic changes and in glands with high grade dysplasia. Specifically, staining for soy bean agglutinin and Ulex europaeus agglutinin was negative in benign and hyperplastic glands and positive in dysplastic glands and carcinoma. Staining for wheat germ agglutinin and peanut agglutinin was weakly positive or negative in normal and hyperplastic glands, whereas it was strongly positive in dysplasia and carcinoma. The staining for Concavalin A, Ricinus communis agglutinin, Dolichos biflorus agglutinin, and Lens culinaris agglutinin showed no difference between normal/hyperplastic and dysplastic glands. The aberrant lectin binding already was evident in low grade dysplasia versus the increased Ki-67 defined-growth fraction that was obvious only in high grade dysplasia and carcinoma.

These findings suggest that the early dysplastic lesions in the prostate may be part of a continuum in the multistep process leading to invasive carcinoma.