Extra Pulmonary Tuberculosis Presenting as Midline Sternal Swelling in Infancy: A Case Report

Sternal tuberculosis is an extremely rare form of Extrapulmonary Tuberculosis (EPTB) in infancy, often posing diagnostic challenges due to its nonspecific presentation. A 10-month-old infant presented with a 20-day history of a progressively enlarging, tender anterior chest wall swelling. The child was otherwise asymptomatic and haemodynamically stable. Examination revealed a firm, tender, 2×2 cm swelling over the manubriosternal junction without erythema or fluctuation. Laboratory findings showed lymphocytic leukocytosis and elevated Erythrocyte Sedimentation Rate (ESR); the Mantoux test was negative, and the chest X-ray was unremarkable. Ultrasonography demonstrated a hypoechoic lesion with internal echoes. Contrast-enhanced Computed Tomography (CT) revealed a well-defined, peripherally enhancing hypodense collection adjacent to the sternum, consistent with a cold abscess. Fine-Needle Aspiration Cytology (FNAC) revealed granulomatous inflammation with necrosis, and Ziehl-Neelsen staining confirmed acid-fast bacilli, establishing the diagnosis of sternal tuberculosis. The child completed a course of eight months of Anti-Tubercular Therapy (ATT), and on eight-month follow-up, the lesion completely resolved. Anterior mediastinal swellings encompass a diverse group of neoplastic and non-neoplastic lesions, presenting a diagnostic challenge due to their varied aetiologies and potential for serious complications. Early recognition of sternal tuberculosis in infants requires high clinical suspicion and comprehensive evaluation. Prompt initiation of therapy ensures favourable outcomes.