Thymus variants on imaging in patients with rheumatoid arthritis—clinical and immunological significance

We sought to clarify the presence of radiographic thymus variants using a scoring system, and their association with clinical and immunological features in RA patients.A total of 387 RA patients were randomly selected from all patients visiting our department who underwent chest CT scanning, with exclusion of patients with thymoma or thymic cyst, or age < 30 years. Thymus size and attenuation score in axial CT images were quantitatively interpreted and assessed. Associations between immunophenotype data and clinical and serological features were analysed in a subset of patients.Thymic enlargement was found in 76 (19.6%) patients, and a thymus attenuation score ≥ 2 was found in 50 (12.9%) patients. The score was significantly associated with antibodies to ACPA positivity. Thymic enlargement was significantly associated with the proportions of CD4+ effector memory T cells.Radiographic thymus variants were frequently observed in RA patients and may reflect an abnormal immune response involved in the pathogenesis of RA.