Bone Scan With SPECT/CT Demonstrated C1 to C2 Involvement in Rheumatic Arthritis.

An 80-year-old man was treated with rituximab for active rheumatoid arthritis until 2019, now controlled with Salazopyrin, prednisolone, methotrexate, and folic acid. However, laboratory data showed elevated C-reactive protein and erythrocyte sedimentation rate. Whole-body bone scan showed bony and joint destruction to the upper cervical vertebra (C spine), bilateral shoulders, wrists, finger joints, ankles, and left knee. SPECT/CT localized the upper C spine uptake to the C1/C2 joint and adjacent C1 and C2 with C1/C2 subluxation. C spine CT showed vertical atlantoaxial subluxation and bony erosions.