Confronting the Clinical Uncertainty Regarding Syphilis

Roy S., a 45-year-old HIV-infected man who is not receiving antiretroviral therapy, comes to clinic with a fever and diffuse maculopapular rash. Medical evaluation finds a newly positive RPR of 1:64 with a positive FTA. His CD4 count is 365 cells/mm3, and his viral load is 35,000 copies/mL. He is treated with 3 once-weekly doses of intramuscular benzathine penicillin. A lumbar puncture is discussed, but Roy declines. Two months later he returns with new complaints of severe tenesmus and bloody stool. On digital rectal exam, a mass is palpable in the anal canal and bloody discharge is evident on the examiner's glove. Flexible sigmoidoscopy shows a flat, ulcerated mass. Biopsies reveal sheets of plasma cells and spirochetes in the mucosa. The patient's RPR is 1:8 at this time. His rectal symptoms persist and, after some delay, he is admitted to the hospital for a full evaluation. He continues to complain of pain and difficulty with bowel movements. He declines repeat digital rectal exam. Now, 5 months after his initial diagnosis of syphilis, his serum RPR is 1:2 and the serum FTA is positive. A lumbar puncture reveals slightly hemorrhagic CSF, which clears; glucose and protein levels are within normal limits. The last tube of CSF obtained has 25 RBC and 8 WBC per mL, all mononuclear cells. CSF VDRL is negative. CSF FTA is trace positive. What do you think is going on with this …