title: Malignant disease as an incidental finding at ¹⁸F-FDG-PET/CT scanning in patients with granulomatous lung disease.
abstract: OBJECTIVE
  Fluorine-18 fluorodeoxyglucose (¹⁸F-FDG)-PET/computed tomography (CT) is used for assessment of the extent and activity of disease in patients with inflammatory granulomatous lung disease, in particular sarcoidosis and tuberculosis. The aim of this retrospective analysis was to assess the value of ¹⁸F-FDG-PET/CT in the identification of previously unknown malignant disease during routine investigation of granulomatous lung disease.
  
  
  METHODS
  From July 2008 to December 2013, a total of 122 patients with tuberculosis (76 male and 46 female patients; age range 19.6-88.6 years, mean 52.8±16.6 years) and 85 patients with sarcoidosis (46 male and 39 female patients; age range 17.8-76.5 years, mean 48.6±13.8 years) underwent ¹⁸F-FDG-PET/CT. Reports were generated in consensus by both a nuclear medicine physician and a radiologist. Possibly malignant findings underwent biopsies and/or follow-up. Quantitative parameters (maximum standardized uptake value) were pooled and compared from reference lesions in each group.
  
  
  RESULTS
  Malignant disease was suspected in 18 of 122 tuberculosis patients and in eight of 85 sarcoidosis patients. Malignancy was finally confirmed in six patients with tuberculosis and in two patients with sarcoidosis. In one single case a malignant lung tumour had been overlooked on PET/CT. Patients were also analysed according to their age. In the patient group older than 60 years, four malignancies were confirmed in 44 tuberculosis patients and in one in 20 sarcoidosis patients, whereas in patients aged between 30 and 60 years only three of 63 tuberculosis and one of 58 sarcoidosis cases showed malignancy compared with the 18 false-positive findings on a total patient basis. The most common site of malignant disease was the chest. Besides the intrathoracic findings, two cases of malignancy were detected outside the thorax. Quantitative evaluation did not reveal any statistically significant difference between the tuberculosis and sarcoidosis groups.
  
  
  CONCLUSIONS
  Differentiation between granulomatous inflammation and malignancy is challenging with ¹⁸F-FDG-PET/CT because of a large number of false-positive findings. The highest probability of detecting coexistent malignant disease was seen in patients older than 60 years who were suffering from tuberculosis. An important feature for identification of malignant disease, especially in the assessment of intrathoracic findings, has turned out to be the CT pattern; quantitative evaluation, in contrast, seems to have little clinical value.
authors: aInstitute of Nuclear Medicine and Endocrinology bDepartment of Pneumology cInstitute of Radiology, Kepler University Clinic, Medical Faculty, Johannes Kepler University Linz, Linz dNuclear Medicine Research Department, IASON, Graz eUniversity Clinic of Nuclear Medicine, Innsbruck Medical University, Innsbruck, Austria fFriedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany Departments of gImaging hNuclear Medicine & PET/CT Centre, Rovigo, Italy iDepartment of Radiology, University of Southern California, Los Angeles, California, USA.
authors: Helmut
authors: H
authors: Huber
authors: Marina
authors: M
authors: Hodolic
authors: Ingrid
authors: I
authors: Stelzmüller
authors: Rainer
authors: R
authors: Wunn
authors: Margit
authors: M
authors: Hatzl
authors: Franz
authors: F
authors: Fellner
authors: Bernd
authors: B
authors: Lamprecht
authors: Domenico
authors: D
authors: Rubello
authors: Patrick M
authors: PM
authors: Colletti
authors: Michael
authors: M
authors: Gabriel
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D005189:False Positive Reactions; D005260:Female; D019788:Fluorodeoxyglucose F18; D006099:Granuloma / Q000175:diagnosis* / Q000000981:diagnostic imaging; D006801:Humans; D033162:Incidental Findings; D008175:Lung Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D049268:Positron-Emission Tomography; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D055815:Young Adult
chemical_list: D019788:Fluorodeoxyglucose F18