Fig. 1

Clinical features of the patients. A Patient 1 had multiple swollen joints ()including joints in both hands, knees, ankles and feet. Nuclear magnetic resonance (NMR) imaging of the wrist, knee and ankle joints of Patient 1 were obtained before tofacitinib treatment in December 2015. Synovitis (), joint effusion and inflammatory oedema of the bone () and periarticular soft tissue were observed in the ankle and knee joints. B Features of paediatric granulomatous arthritis of Patient 2. Symmetric arthritis affecting the wrists, metacarpophalangeal and proximal interphalangeal joints, and knee in June 2018. NMR imaging of the knee and wrist joints of Patient 2 was carried out before tofacitinib treatment. Synovitis, joint effusion, and inflammatory oedema of the bone and periarticular soft tissue were observed in the wrist and knee joints. C Features of paediatric granulomatous arthritis of Patient 3. Symmetric arthritis affecting the wrists, ankle and knee. Nuclear magnetic resonance imaging (NMR) of the knee and ankle of Patient 3 in July 2019. Synovitis, joint effusion, inflammatory oedema of bone and periarticular soft tissue were observed in the wrist and knee joints. D Identification of the NOD2 R334Q (1001G>A) mutation in Patient 1, Patient 2 and their mother