The immunohistochemical markers frequently used in CNS metastases (CK5/6, CD56, CK7, CK20, TTF-1, napsin A, GCDFP-15, CDX2, RCC, PSA, EMA, PAX8, vimentin, and Melan-A) are very useful for the diagnosis of the primary tumor [6]. The gene discussed is PAX8; the disease is renal cell carcinoma.