Infective Endocarditis Masquerading as Rheumatoid Arthritis.

Infective endocarditis (IE) is associated with high inflammatory markers including rheumatoid factor (RF). Diagnosis can be difficult when it presents with musculoskeletal symptoms, and a raised RF titer as it points towards an autoimmune joint disease. It is imperative to rule out IE by echocardiography and blood cultures. A 42-year-old male with type two diabetes mellitus presented to our hospital with severe back pain, hemoptysis, mild pain in multiple joints, and low-grade fever for three months. He was previously seen by a rheumatologist and was clinically diagnosed with rheumatoid arthritis along with a RF level of 505.3 IU/mL. After an extensive investigation, transthoracic echocardiography (TTE) showed vegetations on the ventricular side of the aortic valve. Transesophageal echocardiography (TEE) confirmed vegetations on the aortic valve and also detected anterior mitral valve leaflet perforation with regurgitation. He was treated with ceftriaxone and gentamycin for six and two weeks, respectively. High RF is associated with IE possibly due to an intense immune response generated by a chronic intravascular infection. Echocardiography should be performed in a suspected case as a prompt diagnosis is related to better outcomes.