Renal cell carcinoma marker reliably discriminates central nervous system haemangioblastoma from brain metastases of renal cell carcinoma

Aims: The distinction between central nervous system (CNS) metastases of clear cell renal cell carcinoma (RCC) and CNS haemangioblastoma still poses a challenge to the pathologist. Since both entities occur in von Hippel-Lindau disease, this aggravates the issue. The antibody renal cell carcinoma marker (RCC-ma) has been suggested to identify primary RCCs specifically, but its value for diagnosing metastases of RCC is controversial. The aim was to assess two distinct clones of the RCC-ma for their potential to: (i) identify primary RCCs and (ii) differentiate between CNS metastases of clear cell RCC and CNS haemangioblastomas. Methods and results: Using tissue microarrays, 77% (n = 363; PN-15) and 66% (n = 355; 66.4C2) of clear cell RCCs, and 93% (PN-15) and 74% (66.4C2) of papillary RCCs (n = 46) were immunopositive for RCC-ma, whereas none of the investigated chromophobe RCCs (n = 22) or any of the oncocytomas (n = 15) showed immunoreactivity. Importantly, 50.9% of CNS metastases of clear cell RCCs (n = 55) exhibited RCC-ma expression, whereas all CNS haemangioblastomas (71) were negative. Conclusions: Both RCC-ma clones, despite some variation in their sensitivity to detect clear cell and papillary RCCs, are of value in differentiating subtypes of primary RCC and are excellent markers for discriminating clear cell lesions in the brain.