Anatomic Pathology / SERUM CREATINE KINASE IN WILMS TUMOR

A right-sided renal mass in an 11-month-old girl was diagnosed by percutaneous needle biopsy as Wilms tumor, which on histologic examination was found to be predominantly rhabdomyomatous. As part of the examination, serum creatine kinase (CK) and CK-MB levels were measured and were significantly elevated 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 the hospital with septicemia and was found to have an abdominal mass. A diagnosis of bilateral Wilms tumor was made following percutaneous biopsy of both kidneys; histologic examination confirmed that the tumor was predominantly rhabdomyomatous. Serum CK and CKMB levels also were measured and were significantly 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 serum levels was associated with tumor recurrence, infarction, or chemotherapy-related necrosis. We conclude that these enzymes have clinical usefulness as markers for Wilms tumor showing rhabdomyomatous morphologic features. The development of treatment protocols for Wilms tumor, resulting from the outcomes of the 4 National Wilms Tumor Studies, is arguably one of the great achievements in collaborative medicine of the 20th century, with 2-year relapse-free survivals now exceeding 91%.1 Treatment protocols based on the recommendations of the National Wilms Tumor Study depend on accurate staging of disease at the time of diagnosis, and, in addition, early detection of recurrent disease is essential to maximize favorable outcome. At present, staging relies on clinical, imaging, and surgical findings, and no marker for Wilms tumor that accurately predicts active disease has been described. A tumor marker ideally should be tumor specific and detectable at low levels, while levels should correlate with tumor mass and reflect clinical response to anticancer therapy.2 Although various tumorrelated proteins have been detected in cases of Wilms tumor,3-11 none satisfy these criteria. We studied the clinical usefulness of creatine kinase (CK) and the isoenzyme CK-MB as tumor markers for Wilms tumor showing rhabdomyomatous differentiation. Materials and Methods The study received approval from the Wellington Central Region Health Authority Ethics Committee, Wellington, New Zealand, and procedures followed were within the ethical standards of the Helsinki Declaration of 1975.