Fine-Needle Aspiration Cytology (FNAC)-Based Diagnosis of Disseminated Tuberculosis in an HIV-Positive Patient Presenting With Pyrexia of Unknown Origin.

Pyrexia of unknown origin (PUO) in immunocompromised patients presents a significant diagnostic challenge, particularly when common clinical clues are absent. In human immunodeficiency virus (HIV)-positive individuals, tuberculosis (TB) often manifests atypically, leading to diagnostic delays and potentially worsening outcomes. We report the case of a middle-aged HIV-positive man who presented with persistent high-grade fever without an identifiable source. Despite comprehensive investigations, routine diagnostic tests yielded inconclusive results. Fine-needle aspiration cytology (FNAC) of an axillary lymph node revealed necrotizing granulomatous inflammation consistent with tuberculosis. The initiation of anti-tuberculosis therapy (ATT) led to rapid clinical improvement. This case highlights the importance of considering disseminated TB in the differential diagnosis of PUO in HIV-infected patients, even in the absence of classical pulmonary or systemic signs. FNAC proved to be a pivotal diagnostic tool in identifying the etiology and guiding effective treatment. Early recognition and timely intervention can markedly improve outcomes in such complex presentations.