Tuberculosis Presenting as Incidental Pulmonary Nodules: A Clinical Case Series and Review

Background: The increasing use of diagnostic imaging, particularly low-dose CT (LDCT) for lung cancer screening, has led to an increase in the detection of solitary pulmonary nodules. While these nodules are often evaluated for malignancy, infectious causes, such as tuberculosis (TB), may be under-recognized, particularly in asymptomatic individuals. Methods: We present a case series of five patients diagnosed with tuberculosis during the evaluation of lung nodules in a community-based pulmonary practice in the United States between June 2024 and May 2025. All patients were asymptomatic, and lung nodules were found incidentally or during LDCT screening. Each patient underwent biopsy, either via CT-guided or robot-assisted bronchoscopy, for tissue diagnosis due to concern for malignancy. All patients were smear-negative and had no respiratory or systemic symptoms suggestive of TB. Results: Biopsy in all five cases revealed necrotizing granulomatous inflammation, and subsequent culture or biopsy results confirmed Mycobacterium tuberculosis. One patient was found to have multidrug-resistant TB. Four of the five patients were immigrants from TB-endemic regions. The imaging findings varied, demonstrating cavitation, airway obstruction, or satellite nodules. In all cases, sputum samples remained negative for AFB, and contact investigations, including those among healthcare workers, revealed no evidence of transmission. Conclusion: This series highlights the emerging phenomenon of incidental pulmonary tuberculosis, which is asymptomatic, sputum-negative, biopsy-proven TB discovered during malignancy workup. These cases suggest that such presentations may represent a less infectious form of TB, raising important questions regarding transmission risk, infection control, and diagnostic strategy. As imaging and biopsy tools continue to improve, clinicians should maintain a broader differential diagnosis when evaluating solitary pulmonary nodules, particularly in patients from high-risk populations.