A TALE OF FEVER – RETROPERITONEAL TUBERCULOUS LYMPHADENOPATHY MIMICKING LYMPHOPROLIFERATIVE DISORDER

Pyrexia of Unknown Origin (PUO) still remains one of the diagnostic challenges, often presenting as the sole clinical clue in systemic illnesses. In tuberculosis-endemic countries like India, extrapulmonary tuberculosis (EPTB) must always be considered in PUO workups, even in immunocompetent individuals. EPTB constitutes approximately 15–20% of all TB cases and can involve virtually any organ system. Diagnosing TB especially extra pulmonary TB is often challengeing due to its complexity and atypical clinical presentation Retroperitoneal tuberculous lymphadenopathy is a rare manifestation that lacks specific symptoms and often presents with nonspecific findings, mimicking malignancy or inflammatory disorders leading to delayed diagnosis and management. We report the case of a 51-year-old immunocompetent female presenting with a 15-day history of high-grade, continuous fever with absence of localizing signs or symptoms. Initial routine investigations, including blood cultures, imaging studies, yielded inconclusive results. However, positron emission tomography (PET) of the abdomen revealed metabolically active retroperitoneal lymphadenopathy. Based on imaging features, an initial clinical suspicion of lymphoma was raised. Bone marrow biopsy was performed but returned inconclusive findings. Definitive diagnosis was established through histopathological examination of the lymph nodes, which demonstrated caseating granulomas consistent with tuberculosis, and were positive for acid-fast bacilli. This case underscores the diagnostic challenges associated with extra pulmonary tuberculosis (EPTB), particularly in the absence of definitive clinical and laboratory findings. It highlights the importance of maintaining a high index of suspicion for tuberculosis in patients presenting with prolonged unexplained fever, especially in endemic regions. In this scenario, early utilization of advanced imaging and targeted tissue sampling proved instrumental in establishing the diagnosis, thereby enabling prompt initiation of anti-tubercular therapy and contributing to a favourable clinical outcome.