Can syphilis cause arthritis?
Secondary syphilis due to Treponema pallidum can cause a polyarthritis that can be confused with multiple other connective tissue diseases, such as SLE, RA, vasculitis, sarcoidosis, and spondyloarthropathies. One should suspect syphilis in patients with polyarthritis who have a maculopapular rash on their palms and soles (75%–100%), generalized lymphadenopathy (75%), headache (50%), fever (50%), sore throat (33%), mucosal ulcers, and condyloma lata. The arthritis is symmetric and involves the knees and ankles more than small joints of the hands. Tenosynovitis may be present. Synovial fluid cell counts range from 4000 to 13,000/mm 3 . Spirochetes cannot be seen in the fluid on dark field exam or culturing. Diagnosis is made by either Treponemal antibody testing or nontreponemal testing (rapid plasma reagin test). Treatment for secondary syphilis is benzathine penicillin 2.4 million units intramuscularly once. Concomitant HIV infection should be ruled out.