Disseminated Multi-System Sarcoidosis Mimicking Metastases on 18F-fluorodeoxyglucose positron emission tomography / computed tomography

A 60 year old female with no significant medical history presented with hematuria. A CT scan revealed extensive lymphadenopathy with hypodensities in the liver and spleen and she was referred for an 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography / computed tomography (PET/CT) study to assess for malignancy of unknown primary. PET/CT revealed extensive 18F-FDG avid lymphadenopathy as well as innumerable intensely 18F-FDG avid lung, liver and splenic nodules, highly concerning for malignancy. A PET-guided bone marrow biopsy of the posterior superior iliac spine revealed several non-necrotizing, well-formed granulomas, consistent with sarcoidosis. The patient was managed conservatively and remained clinically well over the subsequent 9 years of follow-up.