Multidetector Computed Tomography Imaging Features of Inflammatory Myofibroblastic Tumors of the Gastrointestinal Tract in Adults: Radiological, Histopathological, and Immunohistochemical Features

Background: Inflammatory myofibroblastic tumors (IMTs) of the gastrointestinal (GI) tract are rare phenomena, and the computed tomography (CT) findings of GI IMTs are not well-established. Objectives: To describe the characteristics of CT scans, pathological specimens, and histological subtypes of GI IMTs in adults. Patients and Methods: The multidetector computed tomography (MDCT) scans of 11 adult patients (8 males, 3 females; age range, 19 - 76 years) with pathologically proven GI tract IMTs (stomach, small bowel, and colon) were retrospectively evaluated by two abdominal radiologists. The radiological features of IMTs were investigated. The imaging features were correlated with three microscopic IMT subtypes (myxoid vascular, spindle cell, and hypocellular fibrous). Immunohistochemistry was also performed on the specimens, including smooth muscle actin (SMA), vimentin, desmin, S-100, and anaplastic lymphoma kinase. Results: The tumor size ranged from 1.4 to 15 cm (mean, 5.7 cm). Two growth patterns were classified, namely, wall-thickening (n = 3) and solitary mass-forming (n = 8) patterns; each pattern was matched with a characteristic pathological subtype. All solitary, well-circumscribed masses corresponded to the spindle cell type. Low-attenuation wall thickening with perienteric infiltration was observed in three patients with a wall-thickening pattern. All solitary, well-circumscribed masses (n = 8) showed homogeneous enhancement with variable internal low attenuation, correlated with cystic degeneration, necrosis, myxoid change (n = 6), and hemorrhagic necrosis (n = 2). No patient showed bowel obstruction, while one patient showed regional lymphadenopathy. Immunophenotypes were not correlated with any growth pattern or histological subtype. Conclusion: The GI IMTs can be classified into two patterns, including wall-thickening and well-circumscribed masses, each matched with a characteristic pathological subtype, which can help explain the tumor behavior. Concomitant CT findings may also provide diagnostic clues for IMT.