Differential expression of GATA-3 in urothelial carcinoma variants.

GATA binding protein 3 (GATA-3) is a novel immunohistochemical marker for urothelial carcinoma (UC); however, few studies have investigated GATA-3's role as a marker for UC variants. We used immunohistochemistry to assess GATA-3 expression in different UC variants, including micropapillary (n = 46), sarcomatoid (n = 43), small cell carcinoma (n = 22), and plasmacytoid (n = 16) variants, and we also compared GATA-3 expression in conventional bladder UC (n = 103) to that in squamous cell carcinoma (n = 14). GATA-3 expression was present in 70% (72/103) of conventional bladder UCs and highly concordant between matched primary and metastatic UCs. The GATA-3 expression levels of the micropapillary variants (57%; 26/46) and plasmacytoid variants (44%; 7/16) were not significantly different from that of conventional UC. However, the GATA-3 expression levels of the sarcomatoid variants (16%; 7/43) and small cell carcinoma variants (5%; 1/22), which only weakly expressed the protein, were significantly lower than that of conventional UC (P < .001). Only 7% of squamous cell carcinomas (1/14) expressed GATA-3, and it was also significantly lower than that of conventional UC (P < .001). GATA-3 expression was not significantly associated with tumor stage or patients' clinical outcomes. In conclusion, GATA-3 expression differed among UC variants. GATA-3 is a useful marker for confirming the urothelial origin of micropapillary and plasmacytoid UC variants but not that of sarcomatoid or small cell carcinoma variants. GATA-3 can also be used in differentiating UC from squamous cell carcinoma.