Pulmonary nodulosis and sterile pleural exudates are well-known extra-articular manifestations in rheumatoid arthritis patients with a positive rheumatoid factor. In some patients, treatment with methotrexate has been postulated as the trigger of these complications. We report a patient with psoriatic arthropathy, negative RF, negative anticyclic citrulinated peptide antibodies but positive antibodies to cardiolipin who developed massive sterile pleural empyema and multiple cavitary pulmonary nodules during methotrexate treatment. We suggest that awareness of methotrexate-induced lung and pleural complications should be extended to other than rheumatoid arthritis diseases, not necessarily accompanied by rheumatoid factor or anticyclic citrulinated peptide antibodies.