A 23-year-old pregnant woman with left-foot and left-ankle ulceration.

(See pages 81–2 for Photo Quiz) Figure 1. Painless shallow ulcer in the oral cavity of a 23-year-old pregnant woman Diagnosis: Secondary syphilis. The patient has secondary syphilis. The diagnosis was established by serological testing and the presence of Treponema pallidum on the biopsy specimen (figure 4). A rapid plasma Figure 2. Diffuse, oval, hypopigmented, nonpruritic macules on the back of a 23-year-old pregnant woman reagin (RPR) test performed by the state laboratory was reactive (titer, 1:32), and a microhemagglutination test for antibody to T. pallidum was also reactive. The patient was sexually active, with multiple partners since an early age. A serological test for Figure 3. Painful round ulceration on the left ankle and plantar surface Figure 4. Silver stain of a biopsy specimen from a lesion on the left ankle (original magnification, ϫ100). Note the presence of spirochetes. HIV was nonreactive. Secondary syphilis may present with many different clinical manifestations—it is frequently referred to as the " great imitator. " It can present as a macular, papular, papulosquamous, or nodular eruption [1, 2]. Any surface area of the body can become involved. Hypopigmented macular lesions are well described in patients with secondary syphilis. The skin lesion is not painful unless it is infected secondarily. In our patient, the lesion was infected secondarily with Staphylococcus aureus. Her symptoms subsided with receipt of treatment for S. aureus infection. Other skin lesions, such as those due to leprosy, sar-coidosis, lymphoma, and deep mycosis, should be considered in the differential diagnosis [3]. The patient was successfully treated with penicillin G. A total of 7.2 million units of benzathine penicillin was administered over a 3-week period. The skin lesions on the left foot healed well and remained asymptomatic. Two months later, the RPR titer decreased to 1:2. The newborn has no signs of congenital syphilis, and the serological RPR test was nonreactive.