Flourine-18 fluoro-2-deoxy-glucose (18F-FDG) positron emission tomography combined with computed tomography (PET/CT) is a useful test for the management of malignant conditions. Inflammatory and infectious processes, however, can cause increased uptake on PET scanning, often causing diagnostic dilemmas. This knowledge is important to the rheumatologist not only because of the inflammatory conditions we treat but also because certain rheumatic diseases impose an increased risk of malignancy either due to the disease itself or as a consequence of medications used to treat the rheumatic diseases. There is an increasing body of evidence investigating the role of PET scans in inflammatory conditions. This paper describes a patient with rheumatoid arthritis who developed pulmonary nodules that showed increased uptake on PET/CT scan and reviews the use of PET scanning in the diagnosis and management of rheumatoid arthritis. 1. Introduction Fluorine-18 fluoro-2-deoxyglucose (18F-FDG) positron emission tomography combined with computed tomography (PET/CT) is a useful test to evaluate malignancies [1]. However, inflammatory diseases may also show increased uptake of 18F-FDG and cause false-positive PET scan results, necessitating further investigations to rule out malignant conditions [2]. Positron emission tomography (PET) is an analytical imaging technology developed to use compounds labeled with positron-emitting radioisotopes as molecular probes to image and measure biochemical processes in vivo [3]. Numerous tracers have been used in conjunction with PET scanning to aid in the diagnosis of various disorders. 18F-FDG has now become the most commonly used radiotracer for PET scanning. Because of the increased metabolic activity of the tumor cells, there is an increased uptake of glucose in tumor cells, thus forming the basis for widespread use of 18F-FDG PET scan in the diagnosis, staging, and management of malignancies. However, the increased uptake of 18F-FDG tracer is not limited to malignant states and has been seen in benign as well as inflammatory conditions such as sarcoidosis, large vessel vasculitis, inflammatory bowel disease, and rheumatoid arthritis (RA) [2, 4–8]. We describe a patient with RA who developed pulmonary nodules, showing increased uptake on 18F-FDG PET/CT scan. We also review the current literature on the use of PET scanning in articular and extra-articular RA. 2. Case Report A 50-year-old Caucasian woman with a history of RA presented with dyspnea on exertion. RA was diagnosed 4 years earlier and has been treated with methotrexate
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