[PET-CT features of the lung benign lesions misdiagnosed as lung cancer]

To analyze why lung benign nodules or masses are misdiagnosed as lung cancer in positron emissin tomography-computed tomography (PET-CT).

We retrospectively analyzed the imaging, clinical and pathological data of 18 patients with benign lung nodules or masses misdiagnosed as lung cancer from May 2012 to August 2013.

18F-fluorodeoxyglucose (FDG) uptake was found in all 18 patients [maximum standardized uptake value (SUVmax) of FDG ranged from 1.2-12.2, mean=4.99]. SUVmax of FDG was greater than 2.5 in 13 patients, and delayed scan was not performed in 17. The contrast enhanced CT scan and high resolution CT (HRCT) was not performed in all the patients. The diameter was greater than 3 cm in 4 patients in CT. There were 5 patients locating in contact with the pleural surface and including clear subpleural fat clearance. Other radiographic signs included regular shape and smooth margin in 7 patients, calcification in 4, satellite opacities in 3, and long spiculation in 1. Neglecting the CT features was the main cause of misdiagnosing the lung benign nodules or masses as lung cancer in PET-CT, while lacking of contrast enhanced CT scan, HRCT and PET-CT delayed scan also led to misdiagnosis.

We should learn to apply the contrast enhanced CT scan, HRCT and PET-CT delayed scan and analyze the CT and PET imagings to avoid the misdiagnosis of lung benign lesions. In-depth study of other tracers is a new direction to prevent the misdiagnosis.