Epithelial membrane antigen as an immunohistochemical marker for transitional cell carcinoma of the urinary bladder.

Epithelial membrane antigen (EMA) was immunohistochemically localized in transitional cell carcinomas of the bladder to clarify EMA staining pattern's relationship to the histological grading and staging of tumors and patient prognosis. Formalin-fixed, paraffin-embedded sections from 101 patients with bladder carcinoma were stained by the indirect immunoperoxidase method. In the lower histological grade and stage of transitional cell carcinoma, the localization of EMA was restricted to the luminal surface of the superficial cells. Membrane and cytoplasmic staining of EMA was frequently found in the intermediate and basal layers of the tumor cells, and the incidence of cytoplasmic staining increased with advancing grade and stage. Stromal staining was frequently observed in cases of higher grade and stage. In addition, these distribution patterns of EMA were well correlated with patient survival. Thus, we differentiated three types of EMA distribution: a luminal type, with very good prognosis; a cytoplasmic type, with fair prognosis; and a stromal type, with relatively poor prognosis. These findings suggest that EMA distribution in bladder cancer could be a valuable indicator for histological grading or staging in pathological diagnosis and for predicting the survival of bladder cancer patients.