Imaging observations of pulmonary inflammatory myofibroblastic tumors in patients over 40 years old

Pulmonary inflammatory myofibroblastic tumors (PIMTs) are extremely rare in adults. If occurring in patients >40 years old, PIMT should be rapidly distinguished from lung cancer. The present study aimed to characterize the imaging features of PIMT in patients >40 years old in order to improve the diagnosis of PIMT. The imaging data of 10 patients with PIMT were reviewed retrospectively. Of the patients, eight underwent computed tomography (CT), two underwent positron emission tomography (PET)/CT and four underwent single-photon emission computed tomography (SPECT). Unenhanced CT revealed 10 lesions with a maximum diameter ranging between 5 and 57 mm located in the lower (n=6) or upper (n=4) lobe, in a peripheral (n=9) or central (n=1) region, and that were well- (n=4) or ill-defined (n=6), and round to oval (n=5) or irregular (n=5) in shape. Calcification (n=3), necrosis (n=6), cavity (n=4), air bronchogram (n=6) and obstructive pneumonia (n=1) were also observed in the patients. Contrast-enhanced CT revealed six lesions with moderate to high contrast enhancement in the arterial and venous phases, including four lesions with delayed enhancement. PET/CT identified two lesions with increased tracer uptake that were homogeneous and heterogeneous and each exhibited a maximal standard uptake value (SUV_max) of 6.0 and 5.4, respectively. The delayed PET/CT revealed foci that each exhibited an increased SUV_max of 6.9 and 5.9, respectively. SPECT demonstrated no definitive bone metastases, but did reveal atypical hypertrophic pulmonary osteoarthropathy in one patient. The combined imaging methods may lead to a more precise evaluation of PIMT in patients >40 years old.