Case Report: Immune reconstitution–related neurological deterioration in advanced HIV infection with multiple opportunistic infections: a diagnostic challenge

Immune reconstitution inflammatory syndrome (IRIS) is a serious complication following antiretroviral therapy (ART) initiation in patients with advanced HIV infection, particularly when the central nervous system is involved and multiple opportunistic infections coexist. We report the case of a 26-year-old man with newly diagnosed advanced HIV infection who developed rapid neurological deterioration shortly after ART initiation during hospitalization. Neuroimaging revealed a necrotic central nervous system mass lesion with extensive edema and mass effect. Serological testing demonstrated prior exposure to <i>Toxoplasma gondii</i> and active <i>Treponema pallidum</i> infection. Despite broad antimicrobial therapy, corticosteroids, and supportive care, the patient experienced progressive clinical deterioration and died. Retrospective reassessment of the clinical course, imaging findings, epidemiological context, and treatment response suggested an IRIS-related inflammatory process, with central nervous system tuberculosis-associated IRIS representing the most plausible underlying mechanism, while toxoplasmosis and syphilis were considered potential concomitant or confounding conditions. This case underscores the diagnostic complexity of IRIS in advanced HIV infection and highlights the importance of a cautious, probabilistic, and evidence-based approach to avoid etiologic misclassification in severe neurological presentations.