Reactivation of Pulmonary Tuberculosis Vs. Connective Tissue Disease Related Interstitial Lung Disease – A Diagnostic Conundrum

Background Distinguishing between reactivation of pulmonary tuberculosis (TB) and interstitial lung disease (ILD) associated with connective tissue diseases poses a diagnostic challenge due to overlapping clinical and radiological features. This case highlights the complexities in differentiating these conditions and the need for a multidisciplinary approach.  Case Presentation An 18-year-old male, a farmer and a part time driver by occupation, presented with cough with expectoration, fever with chills and exertional breathlessness for 15 days. He had a history of incomplete antitubercular treatment therapy (ATT) initiated six months prior based on radiological suspicion of pulmonary TB. Examination revealed digital clubbing, calcinosis cutis and skin thickening of the upper extremities  Investigations: Chest Xray (CXR) and high resolution computed tomography (HRCT) of the thorax demonstrated fibrobronchiectatic and fibrocavitatory changes with diffuse lung involvement suggestive of active Koch'sinfection. However, sputum CBNAAT was negative and further autoimmune workup revealed a positive rheumatoid factor and strongly positive anti-SCL-70 antibodies indicative of an underlying connective tissue disease. Pulmonary function tests showed a restrictive pattern and echocardiography suggested mild pulmonary hypertension.  Management and Outcome The patient was initiated on antibiotics for infection control, antifibrotic therapy for ILD management and closely monitored for disease progression. The case underscores the necessity of comprehensive immunological and microbiological workup in patients with suspected TB, especially in endemic areas to avoid misdiagnosis and delayed intervention.  Conclusion: The overlap in clinical and radiological features between TB and connective tissue disease associated ILD necessitates a high index of suspicion and thorough diagnostic evaluation. Early differentiation is crucial to guide appropriate treatment and improve patient outcomes. A multidisciplinary approach, including pulmonologists, rheumatologists and infectious disease specialists, is essential in managing such diagnostic dilemmas.