Multifocal neuropathic arthropathy in patient with undiagnosed neurosyphilis: A case report.

Although the prevalence of syphilis has decreased significantly, syphilis is still a common cause of neuropathic arthropathy. Tabetic arthropathy means progressive painless joint destruction that is related to neurosensory deficits caused by syphilis. In general, lower limb joints are involved and gradual swelling and instability of the involved joints are observed. Diagnosis of tabetic arthropathy is difficult as its clinical presentation is not specific and differential diagnosis is wide ranging. Hence, diagnosis of tabetic arthropathy requires clinical suspicion and an appropriate serological test. Laboratory tests for the diagnosis of syphilis include nontreponemal tests and treponemal tests. Conventionally, a nontreponemal test such as the Venereal Disease Research Laboratory test or the Rapid Plasma Reagin test is performed first as a screening test for syphilis, followed by a treponemal test to confirm the positive response found in the screening test. However, the sensitivity and specificity of the serum nontreponemal and treponemal tests for the diagnosis of syphilis are different based on the test type and the syphilis stages. We herein report a case of multifocal neuropathic arthropathy found in a patient whose syphilis was not diagnosed due to a nonreactive screening test result.