A Case of Rheumatoid Nodulosis with Extensive Bone Erosion by a Rheumatoid Nodule in the Foot

Rheumatoid nodulosis is a rare variant of rheumatoid arthritis, characterized by similar but milder joint and systemic symptoms compared to typical rheumatoid arthritis. We report a case of rheumatoid nodulosis in a 61-year-old woman with a 6-month history of swelling and pain in her right foot, with subsequent swelling on the back of her right hand, in her left wrist, and over the right tibial tubercle. Radiography showed well-defined radiolucent lesions in several bones of the right foot and the left hand, without narrowing of joint spaces. The 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) scan showed prominent uptake in multiple joints. Magnetic resonance imaging of the right foot showed an ill-defined hypervascular mass lesion with solid and cystic components involving the tarsal and metacarpal bones. Imaging features were suggestive of inflammatory lesions, and the biopsy specimen of the mass in the left foot showed typical histopathologic findings of rheumatoid nodule.