RESUMO
This report describes a case of a term male 3.1 kg, normal delivery, 38 weeks of gestation with a record of hydramnios by prenatal sonography. He had fetal acute suffering and respiratory distress. The first radiographic study showed a mass filling the whole left thorax cage causing erosion of the inferior edge of the third rib. The mediastinum was displaced to the right. Computed tomography scan confirmed a homogeneous tumor that filled the left thorax and displaced the mediastinum to the right without invasion. Surgical biopsy informed of a highly vascularized mesenchymal tumor. The tumor was embolized with Ivalon microparticles obtaining a nearly avascular mass. Complete surgical excision was made, including the whole mass and costal segments. Microscopically, it was an inflammatory myofibroblastic tumor. It was composed mainly of spindle-shaped cells without malignant features. On immunohistochemistry, the tumor showed positive staining for vimentin, whereas antidesmin antibodies and S-100 protein were negative. The aim of this article is to present an extremely uncommon case of neonatal distress caused by an intrathoracic, extrapulmonary myofibroblastic tumor. Complete surgical resection was possible after embolization.