Atypical Dermatological Manifestations of Syphilis in Advanced Hiv: A Case-Based Narrative Review

Syphilis is re-emerging globally, particularly among people living with HIV. Secondary syphilis classically presents with a maculopapular rash involving the trunk and extremities, but atypical cutaneous manifestations are increasingly recognized, especially in immunocompromised patients. We report the case of a 60-year-old male living with HIV with poor adherence who presented with intermittent fever, dry cough, and widespread, non-pruritic polymorphic skin lesions sparing the palms and soles. The patient had a prior history of treated latent syphilis. Physical examination revealed papule-nodular and annular lesions with minimal scaling. Initial diagnostic workup excluded common differentials including monkeypox and fungal infections. Serologic testing confirmed active syphilis with a reactive Rapid Plasma Reagin (RPR) titer of 1:32. Skin biopsy showed dense plasma cell-rich infiltrate, and immunohistochemistry was positive for T. pallidum. Despite negative cerebrospinal fluid findings, neurological symptoms prompted treatment with intravenous penicillin G. Antiretroviral therapy was resumed concurrently. The patient’s symptoms resolved with treatment.