CA9 and neoplasm: In addition to routine diagnostics for the classification of the tumor, e.g., the determination of the isocitrate dehydrogenase (IDH) mutation status and the O6-methylguanine-DNA methyltransferase (MGMT) promoter methylation status, workup included the immunohistochemical detection and quantification of lactate dehydrogenase A (LDHA), carbonic anhydrase IX (CAIX) and Ki67, as well as the quantification of tumor cells, vessels and the extent of necrosis in hematoxylin-eosin (HE) stained tissue sections.