Corticosteroids may favor proliferation of thoracic inflammatory myofibroblastic tumors.

Inflammatory myofibroblastic tumor (IMT) was thought to represent a benign post-infectious or post-inflammatory process cured by surgical resection. However, reports of cases with an aggressive clinical course suggest the need for caution about the prognosis. The treatment of choice is a complete surgical resection, while medical treatment options are limited. Corticosteroid therapy has been used with some success in unresectable lesion. However, rapid progression of lung IMT after prednisone treatment has been reported, raising the hypothesis that corticosteroids may favor a tumultuous proliferation of this lesion, possibly through immunosuppression. We here report a similar observation and suggest that other mechanisms may be involved. A 5-year and 6-month-old boy presented with a 72 hr history of breathlessness, initially responsive to albuterol and prednisone. He represented 15 days later with increasing symptoms despite further prednisone treatment. CT chest scan showed a mass lesion in the tracheal lumen, which on biopsy was found to be an IMT. The possibility that prednisone may have an enhancing effect on IMT cell proliferation is demonstrated through IMT cell culture and discussed.