Malignant Syphilis Mimicking Lymphoma in HIV: A Challenging Case and a Review of Literature Focusing on the Role of HIV and Syphilis Coinfection.

The rate of reported syphilis cases is increasing worldwide, particularly among men who have sex with men. In this scenario, malignant syphilis is a rare, severe form of secondary syphilis, typically observed in immunocompromised individuals and characterized by rupioid skin lesions, together with systemic symptoms that could lead to potentially life-threatening complications. We report the complex case of a 42-year-old man, previously diagnosed with HIV infection, presenting with a five-day history of fever and multiple lymphadenopathies. His immunovirological status was well controlled, and he was fully adherent to antiretroviral therapy. His clinical presentation was severe and ambiguous, with neurological involvement being progressively excluded. The diagnosis was confirmed by serological tests, while histopathological examination of an excised lymph node revealed disrupted architecture with multiple granulomas. Differential diagnosis, including lymphoma and other potential etiologies, was performed. After completion of antibiotic therapy, clinical symptoms completely resolved. No Jarisch-Herxheimer reaction occurred. We also provide an updated review of the current literature, with a focus on HIV coinfection, which is frequently associated with the development of malignant syphilis, and discuss the need for enhanced interventions to prevent sexually transmitted infections, as well as the importance of judicious use of doxycycline post-exposure prophylaxis.