We report on a 26-year-old Japanese man who was referred to our hospital because of anal pain and hematochezia. On admission, in addition to his gastrointestinal symptoms, a generalized maculopapular rash was observed, involving the palms of his hands and soles of his feet. His history and physical examination were compatible with syphilis, confirmed by a high syphilis titer on blood examination. Further tests revealed the presence of HIV infection, with a CD4 cell count of 227/μL. Colonoscopy demonstrated a deep ulcer in the lower rectum, although biopsy specimens did not reveal any syphilis spirochetes, or any other specific microorganisms. Intravenous penicillin G was initiated, resulting in a dramatic improvement of the ulcers along with the skin lesions confirming the diagnosis of syphilis proctitis. A rapid plasma reagin titer test performed 3 months after treatment demonstrated significant decrease, indicating successful treatment.
