High fluorine-18 labeled deoxyglucose uptake in sarcoidosis

A 72-year-old man underwent a whole-body fluorine-18 labeled deoxyglucose (FDG) PET study for cancer screening. On the PET images, multiple foci of intense FDG uptake were noted in the mediastinum. CT scan showed enlarged mediastinal nodes. Chest X-ray was normal. Mediastinoscopy and lymph node biopsy were performed. Histology results showed noncaseating granulomas and a diagnosis of sarcoidosis was obtained. The patient was asymptomatic and was observed without medications. Early reports have indicated that high FDG uptake can be observed in sarcoid granulomas. Inflammatory cells, especially macrophages, are characterized as cells with high glucose use. In interpreting multiple increased FDG accumulations in the mediastinum, sarcoidosis needs to be considered as a differential diagnosis.