Creatine kinase isoenzyme BB increased in serum and tumor tissue of patients with giant cell tumor of bone.

Increased creatine kinase isoenzyme BB (CK-BB) has been observed in sera from patients with brain injuries and occasionally in sera from patients with malignancy. We report here that, in two patients with giant cell tumor of bone (GCT), preoperative serum CK-BB increased to approximately 20 and 90 U/L, but in postoperative serum the CK-BB decreased to normal values. That the tumors contained CK-BB was indicated by electrophoretic analysis and immunohistochemical staining. Furthermore, serum CK-BB was detectable in five additional cases of GCT and in cultured tumor cells from a patient with GCT by an electrophoretic method. These results suggest that CK-BB may be a marker for GCT.