Peanut lectin histochemistry of 120 mammary carcinomas and its relation to tumor type, grading, staging, and receptor status.

Peanut lectin (PNL) is known to bind beta-D-galactosyl-(1-3)-N-acetyl-D-galactosamine, which provides antigenic determination of the Thomsen-Friedenreich antigen ( TFAg ). The aim of this study was to analyse the expression of peanut lectin binding sites in mammary carcinomas and to correlate these with tumor type, histological grading, staging and biochemical receptor status. The series comprised 120 invasive mammary carcinomas and 14 cases with normal breast tissue or benign epithelial proliferations as controls. In controls mainly luminal or apical PNL-binding was discovered, however, in all except three carcinomas a cytoplasmatic localisation of TFAg with three major patterns was found: diffuse, granular-globular and vacuolar reactions. The quantitative-qualitative evaluation of the PNL-staining revealed a statistically significant correlation between globular-vacuolar PNL-reaction and tumor type with a higher percentage of this type of reaction in invasive lobular carcinomas as opposed to tubular and invasive ductal carcinomas. Furthermore a statistically significant relationship was disclosed between PNL- histopositivity and estrogen positive - progesterone positive cases. However, the findings of contradictory PNL-status and hormone-receptor status illustrates clearly the difficulty of predicting the biochemical receptor status. No correlation was found between PNL-histochemistry, histological grading, and pathological staging. The practical implications of PNL-histochemistry of mammary carcinomas are discussed.