[Immunohistological grade of renal cell carcinoma employing anti Leu-M1 antibody and anti EMA antibody].

Attempting to establish more objective grading system of renal cell carcinoma, I studied 104 renal cell carcinoma tissue samples from 52 cases by immunohistochemical technique employing the anti-Leu M1 antibody and the anti-EMA antibody. These 52 cases could be classified into 4 groups according to the reactivity for Leu-M1 (L) and EMA (E), i.e., L+E-, L+E+, L-E+, and L-E-. Considering the expression pattern of Leu-M1 (L) and EMA (E) in normal adult/fetal renal tissue, I speculated that normal cellular characters of the proximal tubules were preserved most well in the L+E- carcinomas, and gradually lost in the L+E+ carcinomas, L-E+ carcinomas, and L-E- carcinomas in this order. The reactions L+E-, L+E+, L-E+, and L-E- were designated immunohistochemical grade 1, 2, 3, and 4, respectively. In most cases, the immunohistochemical grade corresponded with the conventional histologic grade. However, dissociation of more than 2 steps of the grade was observed in some cases. I analyzed the cases with such dissociation and discussed usefulness of the immunohistochemical grading system (as a supplemental role for histologic grading) for renal cell carcinoma.