A single dose of benzathine penicillin G as an effective treatment for malignant syphilis in an HIV-positive patient: a case report

Malignant syphilis (MS) is a rare, atypical manifestation of secondary syphilis. Ulcerative lesions should be suspected as MS when found with supporting microscopic morphology, a high syphilis serology titer test, a Jarisch–Herxheimer reaction (JHR), and rapid disease resolution. To date, there is no specific recommendation for treatment for MS. A 24-year-old HIV-positive MSM patient with a CD4 count of 470 cells/µl presented with a chief complaint of necrotic, ulcerative lesions and oyster shell–like surface plaques on his face, trunk, groin, and extremities. The patient also developed various typical presentations of secondary syphilis. Dark-field microscopy revealed spirochetes. Histopathological examination showed spongiotic dermatitis with many neutrophil cells in the dermis, together with endarteritis and fibrin micro-thrombus in the blood vessels. The patient had a high venereal disease research laboratory (VDRL) titer of 1:512. There was rapid disease resolution following a single injection of 2,400,000-unit benza-thine penicillin G (BPG); together with anti-retroviral therapy, this was supportive treatment for MS. JHR was not observed in this study and many other reports. This case showed that ulcerative lesions with an oyster shell–like surface presenting in HIV-positive patients along with supporting microscopic morphology, high VDRL titer, and a dramatic improvement after antibiotic treatment is highly suggestive of MS. JHR may no longer be a characteristic of MS. A single dose of 2,400,000-unit BPG is sufficient for MS treatment.