title: Extra-articular knee lesion with high fluorodeoxyglucose-uptake on positron emission tomography.
abstract: 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.
authors.forename: Justin C
authors.initials: JC
authors.lastname: Paul
authors.forename: Aasis
authors.initials: A
authors.lastname: Unnanuntana
authors.forename: Stanley J
authors.initials: SJ
authors.lastname: Goldsmith
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Lane
mesh_terms: D001706:Biopsy; D003937:Diagnosis, Differential; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D033162:Incidental Findings; D007717:Knee / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D049268:Positron-Emission Tomography; D011237:Predictive Value of Tests; D019275:Radiopharmaceuticals; D013586:Synovitis, Pigmented Villonodular / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D013710:Tendons / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18