Pathologically confirmed malignant syphilis in an HIV-infected patient

We report a case of pathologically confirmed malignant syphilis in an HIV-infected patient. Physical examinations revealed ulceronecrotic skin lesions. Skin biopsies demonstrated syphilis spirochetes on immunohistochemical stain, and syphilis serological titers were positive. Treatment with intravenous penicillin G was begun, and complete resolution of the skin lesions was observed. A rapid plasma reagin titer test performed 3 months after treatment revealed a 4-fold reduction in the titer, indicating successful treatment.