Tuberculosis on FDG PET-CT: The great imitator

Objectives The aim of this retrospective study was to describe patterns and the added value of whole-body 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) guiding the diagnosis of tuberculosis (TBC).

Methods Whole-body FDG PET/CT was performed in 15 immunocompetent patients. A diverse clinical presentation was de reason to perform the metabolic examination. Seven patients presented clinical lymphadenopathies, five clinical suspicion for peritoneal carcinomatosis , two patients with fever of unknown origin and only one with deterioration of general status. Definitive diagnosis of TBC was proven either on bacteriological or histopathological studies.

Results PET/CT showed misleading imaging mimicking neoplasia in almost all cases. Abnormal hypermetabolic FDG foci were found in 14/15 patients. Pathological FDG foci were also identified in lymph nodes (87% of patients), peritoneum (40% of patients), pleura (27% of patients), lungs (20 % patients), bone/articular sites (20% of patients), soft tissues (13% of patients), liver (7% of patients) and spleen (7% of patients). In 13/15 patients. FDG PET/CT helped in the final diagnosis guiding the biopsy Diagnosis was confirmed by lymph nodes biopsy (n=5), peritoneal biopsy (n=5), pleural biopsy (n=2), sputum cultures (n=2) and lumbar disk biopsy (n=1). All of the 13 biopsy proven sites of tuberculosis were correctly identified by PET/CT.

Conclusions Whole-body FDG PET/CT appears to be a valuable tool in the work up of tuberculosis diagnosis. PET/CT can bring accurate and easy localization for biopsy, in particular lymph nodes and peritoneum which are the most common site of the involvement as well as providing a full image of the extent of the disease.