We describe a patient with systemic lupus erythematosus (SLE) who developed a palmoplantar eruption and positive serologic findings consistent with secondary syphilis. Because of the presence of antiphospholipid antibodies, patients with SLE can have both false-positive nontreponemal and treponemal-specific tests. Western blotting was used to confirm a positive diagnosis of syphilis in our patient. Western blotting is one of the most specific tests in determining whether a patient with SLE has syphilis.1 This case demonstrates the utility of the Western blot with respect to diagnosing syphilis in patients with autoimmune disease.
Levine EG, Green JJ, Heymann WR. Western Blotting as the Confirmatory Test for Syphilis in a Patient With Systemic Lupus Erythematosus. Arch Dermatol. 2004;140(4):490–491. doi:10.1001/archderm.140.4.490