title: 18F-FDG uptake in focal organising pneumonia mimicking bronchial carcinoma.
abstract: OBJECTIVE
  Organising pneumonia (OP) is not a well-known cause of increased18F-FDG uptake, and the relationship of the increased18F-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 with18F-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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Pulmonary Medicine, Gazi University Faculty of Medicine, Ankara, Turkey. dr_aysedemir@hotmail.com.
authors.forename: Ayse
authors.initials: A
authors.lastname: Baha
authors.affiliation: Department of Pulmonary Medicine, Gazi University Faculty of Medicine, Ankara, Turkey.
authors.forename: Fatma
authors.initials: F
authors.lastname: Yildirim
authors.affiliation: Department of Pulmonary Medicine, Gazi University Faculty of Medicine, Ankara, Turkey.
authors.forename: Nurdan
authors.initials: N
authors.lastname: Kokturk
authors.affiliation: Department of Nuclear Medicine, Gazi University Faculty of Medicine, Ankara, Turkey.
authors.forename: Umit Ozgur
authors.initials: UO
authors.lastname: Akdemir
authors.affiliation: Department of Chest Surgery, Gazi University Faculty of Medicine, Ankara, Turkey.
authors.forename: Sedat
authors.initials: S
authors.lastname: Demircan
authors.affiliation: Department of Pulmonary Medicine, Gazi University Faculty of Medicine, Ankara, Turkey.
authors.forename: Haluk
authors.initials: H
authors.lastname: Turktas
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002283:Carcinoma, Bronchogenic / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology; D003937:Diagnosis, Differential; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics*; D006801:Humans; D008175:Lung Neoplasms / Q000175:diagnosis / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D011014:Pneumonia / Q000000981:diagnostic imaging / Q000378:metabolism*; D049268:Positron-Emission Tomography / Q000379:methods; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics*; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
keywords: 18F-FDG uptake; focal organising pneumonia; malignity; pulmonary nodule