Diagnostic challenges of a rare disease with an unusual presentation

Sarcoidosis is a chronic systemic granulomatous disease that can show overlapping clinical features with various rheumatological entities. Even though it can be more commonly associated with Sjögren syndrome and systemic lupus erythematosus, only on rare occasions, it can concomitantly occur with rheumatoid arthritis. While lacking a gold standard diagnostic tool, sarcoidosis remains an exclusion diagnosis. Moreover, an atypical presentation of a rare disease on the background of another systemic disease can be challenging, even for an experienced physician. We present a rare case of a patient with a long-standing history of rheumatoid arthritis treated with methotrexate who developed sarcoidosis with an unusual presentation and possible cardiac involvement.