Inflammatory myofibroblastic tumors in childhood: a report from the Italian Cooperative Group studies

Abstract

Background: Inflammatory myofibroblastic tumors (IMTs) are myofibroblastic lesions with unpredictable biologic behavior that occur at a young age. For this report, the authors investigated clinicopathologic features in a series of pediatric IMTs. The objective of the study was to identify morphologic or immunohistochemical prognostic markers and the possible pathogenic role of human herpes virus 8 (HHV-8).

Methods: Twenty-six patients were observed over a period of 18 years. Clinical/histologic data were reviewed, and immunohistochemical/molecular studies were performed.

Results: Patients ages 8-216 months (median age, 60 months) presented with tumors of the lung-bronchus (8 patients), abdomen (17 patients), and thoracic wall (1 patient). Twenty-one patients underwent complete excision, and microscopic or macroscopic residual disease was present in 5 of those patients. Chemotherapy was received by 5 patients. After a median follow-up of 6.6 years, 24 patients were in complete remission, and 2 patients had died of disease. Local recurrences were observed in 6 patients (including 4 recurrences that occurred after a complete excision). Cytologic atypia, low inflammatory infiltrate, and a rich myxoid pattern were detected in patients who had recurrent disease or a poor prognosis. Anaplastic lymphoma kinase (ALK) was positive in 7 patients (including 2 patients with recurrent disease). No correlation between clusterin expression and prognosis was demonstrated. HHV-8 was identified in 1 pulmonary IMT.

Conclusions: IMTs are locally aggressive lesions. In this series, the local recurrence rate was 23%, and the 5-year and 10-year event-free survival rates were 87.4% and 72.8%, respectively. The results indicated that the treatment of choice is a complete, nonmutilating excision; chemotherapy may be given to patients who have microscopic or macroscopic residual disease, although the results are controversial; cytologic atypia and positive ALK status are more frequent in aggressive tumors, whereas metastatic tumors are negative for ALK; and HHV8 is not involved in the pathogenesis of IMT.