Coexistence of rheumatoid arthritis and sarcoidosis: difficulties encountered in the differential diagnosis of common manifestations.

Two patients with rheumatoid arthritis (RA) and sarcoidosis illustrate the dilemmas posed by their coexistence in the same patient. The first patient with classical RA developed iridocyclitis, interstitial lung disease and cranial neuropathies, initially attributed to extraarticular rheumatoid disease. Subsequent lung and skin biopsy revealed many granulomas consistent with sarcoidosis whereas synovium revealed changes typical for RA. In the second patient with cutaneous and pulmonary sarcoidosis development of persistent erosive polyarthritis and a subcutaneous nodule with typical pathology permitted the diagnosis of coexistent RA. These cases emphasize that uveitis alone or multiple cranial neuropathies are not features of RA and symptomatic interstitial lung disease in patients with RA warrants further investigation.