Pediatric inflammatory myofibroblastic tumor: Anaplastic lymphoma kinase (ALK) expression and prognosis

Background. Pediatric inflammatory myofibroblastic tumor (IMT) is rare, with unpredictable clinical behavior. Recently, it has been associated with anaplastic lymphoma kinase (ALK) expression. Methods. Patients under age 16, treated for IMT between 1976 and 2000 were reviewed. Mean follow-up was 8 years (range 1 month-22 years). Results. Eight children had IMT, with a mean age of 6 years (range, 11 months-14 years) and female to male ratio of 3:1. Tumor location was lung (four patients), abdomen (two patients), lung and abdomen (one patient), and abdomen, head, and neck (one patient). Presenting symptoms included anemia (seven patients), fever (six patients), and dyspnea (four patients). Laboratory results included thrombocytosis (six patients), hypergammaglobulinemia (four patients), elevated sedimentation rate (four patients), and leukocytosis (three patients). lmmunohistochemistry revealed ALK expression in four of eight tumors. Four children had complete resection and are alive. Two of these children had ALK-positive tumors. Four patients had incomplete resection, and two had recurrences treated successfully with resection and radiotherapy; the other two died of disease. For the incomplete resection patients, those that were ALK-positive lived, and those that were ALK-negative did not. Conclusions. Eight children were treated for IMT over a 15-year period. ALK expression was found in half the tumors. Prognosis was improved with ALK expression and complete surgical resection.