F-FDG uptake in focal organising pneumonia mimicking bronchial carcinoma.

BACKGROUND AND AIMS

Organising pneumonia (OP) is not a well-known cause of increased F-FDG uptake, and the relationship of the increased F-FDG uptake to clinical parameters has not been clearly identified. This study aims to assess the role of positron emission tomography-computed tomography (PET-CT) for the diagnosis of focal organised pneumonia that may mimic malignity because of mass-like lesions on the radiological images it causes.

METHODS

Among 40 patients of whom histopathological exams were consistent with OP, medical records of 14 focal OP patients diagnosed with surgical biopsy were evaluated retrospectively.

RESULTS

There were 10 male (71.4%) and 4 female (28.6%) patients. The mean age at the time of diagnosis was 57.2 ± 11.7 years, ranging from 38 to 85 years. Nine subjects (64.3%) were smokers. Eleven patients (78.5%) had symptoms, the remaining 3 patients (21.5%) were asymptomatic. Three patients (21.3%) had a history of malignancy. Focal lung lesion was initially detected by chest radiography in 10 patients (71.4%) and by computed tomography (CT) scan in all patients. CT scan showed a single lesion in 12 (85.7%) patients. The lesions were located in the right lung of the half of patients (50%) and in the left lung of the other half. The median diameter of the lesions was 3.4 cm (range, 1.8-6.0 cm). PET with F-FDG was performed in all patients, and hypermetabolic activity of the focal lung lesion was demonstrated in all cases. The median values of maximum standardized uptake value was 3.5 ± 2.7 (min 2.1-max 13.1).

CONCLUSION

Focal OP is a discrete form of OP that is associated with unifocal lesions on radiological images, and it can easily mimic lung cancer because of positivity on PET scans. There are no specific findings of PET scan for the diagnosis of OP.