PAX8 and urothelial carcinoma: By immunohistochemistry, nephrogenic adenoma should stain positive for PAX8, PAX2, keratin 7, and keratin 34betaE12, and typically does not stain for NKX3.1, p63 or PSA.12,13 Notably, GATA3 is positive in 40% of specimens with nephrogenic adenoma and should be interpreted with caution when used to differentiate from urothelial carcinoma.