Atypical clinical presentation of rheumatoid arthritis

Introduction. Rheumatoid arthritis is a systemic autoimmune disease with inflammation of the joints as its hallmark. Extra-articular manifestations affect nearly half of the patients either at the onset of disease or later during the disease course. Case outline. A 43-year-old man complained over a chest pain, dry cough and fatigue. Diagnosis of pericarditis was made based on echocardiography findings. Due to worsening of respiratory symptoms he was admitted to the hospital. Initial diagnostic workup revealed elevated concentrations of acute phase reactants, pericardial effusion and bilateral pulmonary nodules. Pathohistological analysis of lung nodules ruled out malignancy and tuberculosis. He was treated with colhicine which led to a regression of a pericardial effusion. Afterwards, due to arthritis of the right wrist, high erythrocyte sedimentation rate and C-reactive protein, positive immunoserology and bone erosion at the distal ulna diagnosis of seropositive rheumatoid arthritis was established. He was treated with antimalarial, methotrexate and glucocorticoids until suffering from COVID-19 pneumonia which triggered arthritis flare. Owing to the loss of efficiency of combination therapy with methotrexate and glucocorticoid, baricitinib was added to the treatment. Low disease activity was achieved after 3 months of administering baricitinib and methotrexate, and no adverse events occurred during 20 months of this therapy. Conclusion. Every patient with pericarditis of unknown etiology should be diagnostically evaluated in term of connective tissue disease including rheumatoid arthritis, because the initial clinical presentation in some group of patients could lack characteristic synovitis.