IMPORTANCE Immune checkpoint inhibitors (ICIs) have transformed the treatment paradigm for an ever-increasing number of cancers. However, their use has also led to the emergence of immunerelated adverse events, such as ICI-induced inflammatory arthritis. A reproducible, reliable, and accessible modality is needed to assess and distinguish early ICI-induced inflammatory arthritis and help in management. Magnetic resonance imaging (MRI) of joints may be helpful for early diagnosis, guiding therapeutic decision-making, and identifying patients at high risk for erosive disease.OBJECTIVE To assess the role of MRI of joints in patients with ICI-induced inflammatory arthritis. DESIGN, SETTING, AND PARTICIPANTSThis retrospective case series included patients enrolled at the National Institutes of Health Clinical Center in Bethesda, Maryland. Patients were evaluated by the rheumatology consultation service between December 27, 2016, and May 28, 2019. A retrospective health record review was performed to determine demographic characteristics, clinical characteristics of inflammatory arthritis and malignant tumors, and imaging findings. Inclusion criteria were patients who were enrolled on various institutional review board-approved protocols of ICIs, developed joint-related symptoms, and had MRI data for at least 1 joint. Data were analyzed from EXPOSURES Undergoing MRI of at least 1 joint. MAIN OUTCOMES AND MEASURESAll MRIs were reviewed for synovitis, tenosynovitis, bone marrow edema, and soft tissue conditions. RESULTS A total of 8 patients (mean [SD] age, 58.8 [5.2] years; 6 women and 2 men) between the ages of 50 and 65 years who were undergoing ICI therapy for a variety of malignant tumors were included in this study. Only 1 patient was receiving combined ICI therapy. The results of 13 separate MRI examinations were reviewed. The most commonly performed MRIs were of the hands and wrists (9 MRIs), followed by knee examinations (3 MRIs). Tenosynovitis and synovitis were frequently seen in the hands and wrists. Bone marrow edema and erosions were also found in 3 patients, suggesting early damage. In larger joints (ie, knees and ankles), joint effusions and synovial thickening were characteristic. Most patients (5 patients) were treated with corticosteroids and had good responses.In patients with high-risk features on MRI imaging (eg, bone marrow edema, erosions), diseasemodifying antirheumatic drug therapy was also discussed as a treatment option.CONCLUSIONS AND RELEVANCE These findings suggest that advanced imaging may help to distinguish ICI-induced inflammatory arthritis from other causes of joint pain, aid in identifying (continued)

Leukopenia is a common manifestation of SLE. Addition of immunosuppressive therapy in a SLE patient who is already leukopenic is a clinical concern. It could worsen leukopenia, increase the risk of infection, or both. The aim of this study was to analyze the immediate effect of mycophenolate mofetil on the white blood cell count and the rate of infection in SLE patients. Two hundred and forty-four patients within the Hopkins Lupus Cohort who were newly started on mycophenolate mofetil were included in the study. The white blood cell count and interval infection history on the day mycophenolate mofetil was started were compared with the white blood cell count and interval infection history at the next visit. The study was based on 244 patients who began taking mycophenolate mofetil in the cohort. The study population included 47 % African Americans, 44 % Caucasians, and 9 % other ethnicities. There was a slight but not statistically significant increase in the white blood cell count (6.63 vs. 7.01), after starting mycophenolate mofetil. Patients with a baseline white blood cell count <3000/mm3 did have a statistically significant increase in the white blood cell count after starting mycophenolate mofetil (2.57 vs. 5.13, P = 0.0047). We also found a statistically significant increase in the risk of bacterial infection (but not viral infection) after starting mycophenolate mofetil (4 vs. 9 %, P = 0.0036). Leukopenia does not worsen with mycophenolate mofetil. However, mycophenolate mofetil appears to slightly increase the rate of bacterial (but not viral) infection.

A 58-year-old white woman with history of metastatic human papillomavirus-positive cervical adenocarcinoma presented with multiple joint deformities. Her initial symptoms started 1 month after the initiation of nivolumab, which was 1 year prior to the index visit. Treatment with nonsteroidal anti-inflammatory drugs failed, and the patient had a partial response to intra-articular steroids. She refused systemic therapies owing to concern about diminishing the effectiveness of nivolumab. Despite the joint symptoms, nivolumab treatment was continued for a year. Evaluation showed fixed swan neck deformities in multiple fingers (Figure , A). There was evidence of chronic synovial hypertrophy with no active synovitis on examination. The results of a comprehensive autoantibody blood panel, including antinuclear antibody, rheumatoid factor, and anti-citrullinated peptide antibody, were unremarkable. Plain radiographs of the hands demonstrated diffuse osteopenia, joint space narrowing, and multiple deformities. Magnetic resonance imaging of both hands revealed multifocal osseous erosions (Figure , B), synovitis, and tenosynovitis. DiagnosisC. Nivolumab-induced inflammatory arthritis 9. Schadendorf D, Wolchok JD, Hodi FS, et al. Efficacy and safety outcomes in patients with advanced melanoma who discontinued treatment with nivolumab and ipilimumab because of adverse events: a pooled analysis of randomized phase II and III trials.