Metastatic Alveolar Rhabdomyosarcoma with Increased Serum Creatine Kinase MB and Cardiac Troponin T and Normal Cardiac Troponin I

Abstract

We describe a 53-year-old man with metastatic alveolar rhabdomyosarcoma who had a massively increased creatine kinase MB (CK-MB) mass and index. The CK-MB increase was initially interpreted as evidence of myocardial infarction (MI), but the CK-MB remained increased. The patient had increased serum concentrations of cardiac troponin T (cTnT) and normal cardiac troponin I (cTnI). We theorize that tumor anaplasia caused malignant myocytes to re-express CK-MB and cTnT isoforms. Rhabdomyosarcoma release of both CK-MB and cTnT has not been described previously. Serum CK and lactate dehydrogenase (LD) activities were assayed at 37 °C with the Hitachi 911 automated analyzer [Boehringer Mannheim (BM)]. CK-MB mass was measured with the Access (Beckman Instruments) immunoenzymatic assay. Serum cTnT was evaluated using a second-generation Elecsys 1010 immunoassay (BM). Serum cTnI was analyzed using both the AxSYM (Abbott) microparticle enzyme immunoassay and the Opus Plus (Dade Behring) fluorogenic two-site immunoassay. The patient presented to a community hospital with acute, bilateral leg weakness. He had a 3-week history of worsening thoracic back pain and lower extremity paresthesias, and 3 months earlier he had discovered a subcutaneous mass of his left foot. Foot x-ray at that time was unremarkable. The patient’s neurologic examination revealed that lower extremity motor power was decreased to 2+/5. He was unable to walk. His deep tendon reflexes were diminished, and his plantar responses were abnormal bilaterally. The patient was continent of urine but had anal sphincter laxity. He had decreased sensation below the nipples. Spinal cord compression was diagnosed. Computerized tomography scan revealed a …