Background: [F-18]-fluorodeoxy-D-glucose (18FDG) positron emission tomography (PET) is a sensitive modality for detecting malignant lesions. The purpose of the present study was to describe unknown bone and soft tissue lesions in adults identified at cancer screening using PET.
Methods: A total of 4283 individuals of more than or equal to 40 years of age were enrolled. All individuals underwent scans from the base of the skull to proximal thigh. The images were reviewed and a consensus was reached by two board-certified radiologists and a nuclear medicine specialist for the diagnoses. Diagnoses of the lesions were confirmed by histological examination, typical radiologic findings, obvious progression in number and/or size of the lesion on follow-up examinations, and medical examination of interview.
Results: Unsuspected focal abnormality in the bone and soft tissue were found in 62 individuals (1.4%). The mean size of the lesion was 26 mm (range, 6-155 mm). There were 29 bone lesions (47%) and 33 soft tissue lesions (53%). A malignant lesion was found in one case (1.6%) and histologic diagnosis was primary non-Hodgkin lymphoma of the vertebra. Other major diagnoses were healing bone (n = 11, 18%) and benign cystic lesions of bone and soft tissue (n = 9, 15%), and brown fat of soft tissue (n = 4, 6%).
Conclusion: Unsuspected bone and soft tissue lesions of a wide variation of pathologic and clinical diagnoses were encountered at cancer screening using PET. Correlation with clinical history and other imaging findings is essential in the differential diagnosis.