GATA3 expression in sarcomatoid urothelial carcinoma of the bladder

The current available data on GATA-binding protein 3 (GATA3) expression in sarcomatoid urothelial carcinoma are limited, especially in the non-tissue microarray-based setting. In this study, we analyzed the expression of GATA3 in sarcomatoid urothelial carcinoma of the bladder in cystectomy/cystoprostatectomy specimens. A search was made through our surgical pathology and consultation files for cystectomy/cystoprostatectomy specimens with a diagnosis of sarcomatoid urothelial carcinoma. Only cases with available tissue blocks were selected. Immunohistochemical staining for GATA3 was performed, and staining in adjacent/overlying conventional urothelial carcinoma and/or benign urothelium was also documented. Twenty-two cases were obtained. Of 22 cases, 16 (73%) of sarcomatoid urothelial carcinoma were positive for GATA3. In the 7 (27%) of 22 cases that were negative for GATA3, it was observed that these cases were predominantly composed either of pleomorphic undifferentiated sarcomatoid areas or foci composed of extensive heterologous elements (chondroid, osteoid, or rhabdoid). GATA3 staining was positive in the adjacent/overlying conventional urothelial carcinoma and/or benign urothelium in all cases. This is one of the largest studies to date analyzing the expression of GATA3 in sarcomatoid urothelial carcinoma in cystectomy/cystoprostatectomy specimens. GATA3 is expressed in most cases of sarcomatoid urothelial carcinoma. Negative expression may, however, be observed in cases composed predominantly of pleomorphic undifferentiated sarcomatoid areas or extensive heterologous elements. We recommend including GATA3 in the panel of immunohistochemical stains for sarcomatoid carcinomas of unknown origin, especially if a bladder primary is being considered in the differential diagnosis.