Clinicopathological characteristics of lymphoproliferative disorders in 232 patients with rheumatoid arthritis in Japan: A retrospective, multicenter, descriptive study

Abstract Objective To describe the clinicopathological characteristics of lymphoproliferative disorders (LPDs) in patients with rheumatoid arthritis (RA). Methods In this multicenter case series, we retrospectively reviewed the medical records of RA patients who were newly diagnosed as having LPDs with or without biopsy confirmation between 2000 and 2017 in eight hospitals in Japan. Results We included 232 patients with LPDs. The median age was 67 years (interquartile range [IQR], 60–73 years), and 77.1% were female. At the time of LPD diagnosis, 94.8% and 62.6% of the patients were methotrexate users and in remission or had low RA disease activity, respectively; lymphadenopathy and extranodal involvement were present in 77.1% and 51.9%, respectively. Major extranodal sites were the lungs and oral/oropharyngeal mucosa. The most common LPD pathological subtype was diffuse large B-cell lymphoma (40.5%), followed by classic Hodgkin lymphoma (10.8%), Epstein–Barr virus-positive mucocutaneous ulcer (7.7%), and reactive lymphoid hyperplasia (6.2%). The clinical and laboratory characteristics varied across the pathological subtypes. Conclusion LPD occurred mainly in methotrexate users, while RA disease activity did not seem to be associated with LPD development. Although the clinical manifestations vary among pathological subtypes, manifestations of LPD in patients with RA can include lymphadenopathy, extranodal mass, and mucocutaneous ulcer.