Elevation in creatine kinase isoenzyme-MM associated with hepatocellular carcinoma: a case report and review of literature

We report the case of a 79-year-old woman with hepatocellular carcinoma (HCC) who presented with creatine kinase (CK)-MM elevation. On admission, her serum CK-MM level exceeded 4000 IU/L (normal, 44–206 IU/L), and computed tomography revealed two HCCs in hepatic segment VIII (23 mm, 86 mm). The patient denied experiencing muscular symptoms such as weakness or pain. Hypothyroidism, ischemic heart disease, muscular dystrophy, autoimmune myopathy, drug-induced rhabdomyolysis, and paraneoplastic inflammatory myositis syndrome (PIMS) were included in the differential diagnosis for high CK-MM, but none were suspected. Although the cause of elevated CK-MM was not elucidated, an HCC-related mechanism was considered and the tumor was resected. The CK-MM levels declined gradually to 300 IU/L postoperatively without any special perioperative management. Nineteen cases of HCC-associated CK-MM elevation have been reported in English thus far, in all of which, inflammatory myositis was concluded as the cause of CK-MM elevation. However, in this case, the elevation of CK-MM was associated with HCC-related mechanisms distinct from PIMS, suggesting HCC-related mechanisms should not be excluded as a cause of high CK-MM, even though PIMS is negative.