Usefulness of GATA3 and p40 immunostains in the diagnosis of metastatic urothelial carcinoma in cytology specimens.

GATA3 (GATA-binding protein 3) expression in urothelial carcinoma (UC) and mammary carcinomas has been recently reported. However, to the authors' knowledge, studies examining GATA3 staining of metastatic UC (MUC) in cytology specimens are lacking. Delta Np63 (p40) has been shown to be expressed highly selectively in squamous cell carcinomas (SCCs) but the literature concerning the expression of p40 in UC is limited and controversial. In the current study, the authors evaluated the usefulness of GATA3 and p40 in the diagnosis of MUC in cytology specimens. Thirty-two MUC cytology cases and 44 controls (22 UC cases and 22 SCC cases) were stained for GATA3, p40, and p63 and nuclear staining intensity and the percentage of positive cells were recorded and compared. MUC cytology cases stained positive for GATA3, p40, and p63 in 78.13%, 80.65%, and 61.29% of cases, respectively, with moderate/strong staining intensity. MUC cases had a significantly higher percentage of GATA3 positivity compared with SCC controls (P<.001), but GATA3 positivity was not found to be significantly different from UC controls (90.91%) (P = .28). For p40 positivity, there was no significant difference observed between MUC cases, UC controls (95.45%), and SCC controls (90.91%) (P=.29). p63 positivity was found to be significantly lower in MUC cases compared with UC controls (95.45%) and SCC controls (95.45%) (P<.01). The results of the current study demonstrate that GATA3 is useful in confirming the diagnosis of MUC in cytology specimens and in distinguishing between MUC and SCC. p40 is a valuable adjunct to GATA3 in the diagnosis of MUC in cytology specimens, especially when SCC is not part of the clinical differential diagnosis.