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.