Extra‐articular involvement of rheumatoid arthritis in three seropositive patients in the absence of initial joint involvement

Introduction Extra‐articular involvement (EAI) in rheumatoid arthritis (RA) is rare, severe and usually presents after years of joint involvement. Onset of RA as lung involvement has been published. We describe a series of three patients with strongly positive anti‐citrullinated peptide antibodies (ACPA) and rheumatoid factor (RF) positive in the absence of joint symptoms, but with significant EAI. Methods This is a descriptive case series of three patients evaluated in an academic medical center rheumatology clinic. Results A 50‐year‐old female presented with severe recurrent scleritis in the background of strongly positive ACPA, but no joint involvement. Her ocular disease responded well to rituximab. Four years later, she developed peripheral inflammatory arthritis consistent with RA. A 74‐year‐old male presented after developing recurrent steroid‐dependent serositis (pleuro‐pericarditis) and interstitial lung disease (ILD). Serology was notable for strongly positive ACPA, but no joint involvement. Serositis responded well to adalimumab. Two years after initial symptoms, he developed peripheral joint involvement after holding adalimumab. A 56‐year‐old female presented with an isolated, biopsy‐proven subcutaneous rheumatoid nodule. Subsequently, she developed pancytopenia and fatigue. She tested strongly positive for ACPA and RF. Bone marrow biopsy was negative for malignancy and she had no evidence of infection. She responded to steroids and hydroxychloroquine and had not developed joint involvement after 2 years of follow‐up. Conclusion EAI as an onset of RA is a complex and not easily recognized entity if typical joints involvement is not yet present. Early diagnosis may help guide specific therapy and prevent sequelae and co‐morbidities.