A Calcified Mass Within the Thorax

Abstract

Inflammatory myofibroblastic tumor (IMT) is a rare proliferative lesion also referred to as an inflammatory pseudotumor, among a number of other pseudonyms. IMTs are comprised of variable amounts of spindle cells, collagen, and inflammatory cells, including plasma cells, foamy histiocytes, and lymphocytes. IMTs may affect different organ systems, but the thorax is the most commonly affected, particularly the lung or the airways, and less commonly the mediastinum. IMTs exhibit a variable biological behavior, ranging from spontaneous involution to locally aggressive behavior, including recurrence after resection, regional extension, and even distant metastatic deposits. Genetic assessment has revealed neoplastic features in some IMTs, but not others, rendering the IMT classification ambiguous. Pulmonary IMTs affect patients over a wide age range, but are most frequently encountered in children, adolescents, or young adults. IMTs are occasionally discovered asymptomatically, but may present fever, dyspnea, chest pain, or hemoptysis. Thoracic IMTs primarily present on imaging as a solitary pulmonary nodule or mass, which may show calcification: an appearance suggestive of IMT when a nodule or a mass is encountered in a young patient. The margins of thoracic IMTs range from circumscribed to lobulated or poorly defined. Intense contrast enhancement is common with IMTs, and the lesions may even be associated with aberrant systemic arterial supply, simulating pulmonary sequestration. Thoracic IMTs are usually treated with limited surgical resection, with corticosteroid therapy or radiation utilized for unresectable patients or patients with inadequate surgical margins.