Rheumatoid Arthritis with Generalized Lymphadenopathy Mimicking Lymphoma on Positron Emission Tomography/Computed Tomography with 18F-Fluorodeoxyglucose.

A 42-year-old male presented with weight loss and progressively increasing pain and swelling in joints over the past 3 months. Contrast-enhanced computed tomography (CT) demonstrated pleuropulmonary opacities and supra/infradiaphragmatic lymph nodes enlargement. Positron emission tomography (PET/CT) with 18F-fluorodeoxyglucose showed intensely increased tracer uptake in joints, in pulmonary opacities, as well as in thoracic, iliac, and inguinal nodes. On suspicion of lymphoma with synovial involvement, he was submitted to lymph node and synovial biopsy, which revealed reactive follicular lymphadenopathy and synovium inflammatory changes, respectively. Rheumatoid factor resulted increased, and thus, diagnosis of rheumatoid arthritis with related lung and lymph node involvement was made.