The thoracic mass: An unusual etiology

Inflammatory myofibroblastic tumor (IMT) is a rare proliferative lesion also known as inflammatory pseudotumor. IMTs consist of variable amounts of spindle cells, collagen, and inflammatory cells, including plasma cells, foamy histiocytes, and lymphocytes. IMTs have been reported in numerous organ systems, but most commonly are encountered within the thorax, usually the lung or tracheobronchial tree, and uncommonly the mediastinum.IMTs show variable biological behavior, ranging from spontaneous regression to locally aggressive behavior, including recurrence after resection and even distant metastatic disease. Genetic analysis has shown features consistent with true neoplasia in some IMTs, but not others; these observations, and the variable biological behavior of these lesions, make them difficult to properly classify.Pulmonary IMTs occur over a wide age range, but are most commonly encountered in children, adolescents, or young adults. These lesions are often discovered asymptomatically but may present fever, chest pain, dyspnea, or hemoptysis-these latter 2 symptoms may be more frequently encountered in airway lesions.The imaging findings of thoracic IMT primarily consist of a solitary pulmonary nodule or mass, which may show calcification-this appearance, in a young patient, while not pathognomonic, suggests IMT.The margins of thoracic IMTs may be smoothly circumscribed or lobulated or poorly defined. These lesions often show intense contrast enhancement and may even be associated with aberrant systemic arterial supply, resembling pulmonary sequestration.The treatment of choice for thoracic IMT is limited surgical resection, with corticosteroid therapy or radiation reserved for unresectable patients or patients with inadequate surgical margins.