Secondary Syphilis with Nodular Vasculitis Mimicking Behçet's Disease
A 22-year-old man visited the Department of Rheumatology with several months history of recurrent oral ulcers, genital erosions () and crops of hyperpigmented tender nodules located on both shins (). The initial diagnosis was BD, which led to the initiation of steroid therapy. After 1 week, the nodular skin lesions on both shins had slightly improved, but the genital erosions and oral ulcers were aggravated and fever developed. To evaluate the patients for other diseases, the serum rapid plasma reagin (RPR) test was performed, and the result was positive. The patient had no history of medication before the appearance of the skin lesions. He did, however, have a history of heterosexual intercourse with multiple partners without the use of a condom. Laboratory profiling revealed a white blood cell count of 7,900/mm3, a hemoglobin level of 16.3 g/dL, a platelet level of 313,000/mm3, and a high sensitivity C-reactive protein level of 7.57 mg/dL. Hepatitis B, hepatitis C, and HIV serology were negative. The immunoglobulin (Ig) M-fluorescent treponemal antibody absorption test (FTA-ABS), the IgG-FTA-ABS, and the Treponema pallidum hemagglutination assay were all reactive. Spirochetes were also identified in a scrotal specimen using the Warthin-Starry stain (). The results of skin biopsies from his shins were concordant with nodular vasculitis (). After the diagnosis of secondary syphilis was made, intramuscular benzathine penicillin G was immediately initiated at a dosage of 2.4 MU once per week for 3 weeks. After the initiation of penicillin treatment, his signs and symptoms, including skin lesions, gradually improved. All lesions had resolved after 3 months. Non treponemal titer was also decreased from 2.6 RPR unit (R.U) to 1.5 R.U.