Serum creatine kinase levels parallel the clinical course for rhabdomyomatous Wilms tumor

A right-sided renal mass in an 11-month-old girl was diagnosed by percutane ous needle biopsy as Wilms tumor which on histologic examination was found to be predominantly rhabdomyomatous. As part of the examination, serum crea tine kinase (CK) and CK-MB levels were measured and were significantly elev ated at 994 U/L (reference range, 42-180 U/L) and 40 U/L (reference range, 0-3 U/L), respectively. Subsequently, an 8-month-old girl was admitted to t he hospital with septicemia and was found to have an abdominal mass. A diag nosis of bilateral Wilms tumor was made following percutaneous biopsy of bo th kidneys; histologic examination confirmed that the tumor was predominant ly rhabdomyomatous. Serum CK and CKMB levels also were measured and were si gnificantly elevated at 685 U/L and 84.4 U/L, respectively. In both cases, the serum CK and CK-MB levels reflected the clinical course; elevation in s erum levels was associated with tumor recurrence, infarction, or chemothera py-related necrosis. We conclude that these enzymes have clinical usefulnes s as markers for Wilms tumor showing rhabdomyomatous morphologic features.