Extra-articular knee lesion with high fluorodeoxyglucose-uptake on positron emission tomography
Paul, J.C.; Unnanuntana, A.; Goldsmith, S.J.; Lane, J.M.
Bulletin of the Hospital for Joint Disease 71(2): 170-174
2013
ISSN/ISBN: 2328-5273 PMID: 24032621 Document Number: 665459
Pigmented villonodular synovitis (PVNS) is an uncommon musculoskeletal tumor that is typically benign and often diagnosed radiologically by magnetic resonance imaging (MRI). Fluorodeoxyglucose (FDG)-uptake positron emission tomography (PET) is an imaging tool primarily used in oncology to evaluate malignancy. FDG measures metabolic activity with standardized uptake value (SUV). A high SUV is suggestive of malignancy. We report a case of PVNS detected incidentally by FDG-PET as an extracapsular mass adherent to vastus medialis tendon with a high SUV of 15.1. Given the patient's history of cancer and the high SUV, the lesion was initially considered a malignancy. The objective of this case report is to illustrate that even a high-SUV mass detected with PET imaging does not necessarily indicate malignancy, and thus a benign lesion can also demonstrate such elevated signal.