Immunohistochemical study on spontaneous transitional cell carcinoma of urinary bladder in an Indian water buffalo (Bubalus bubalis)

A spontaneous, rare and focally infiltrating type of transitional cell carcinoma (TCC) in urinary bladder from a buffalo is reported. The tumorous vegetative growth in the lumen was observed, as scattered papilliferous growth with broader base involving larger luminal surface area with histological evidence of atypical appearance of transitional epithelium and hyperplasia with irregular stratification at some places. The atypical tumor cells invading the underneath stroma, were discernible as lobules having confluent sheets of cells (cell nests) at numerous places. Following immuno-histochemistry, the atypical tumorous cells appeared moderately to highly reactive in response to Ki-67, a nuclear proliferation marker, while marked response to cytoplasmic cytokeratin 7 (CK7) and low to poor reactivity towards cytokeratin 20 (CK20) in atypical transitional epithelium and invasive cell nest was observed.