When It’s Not TB: A Case of Metastatic Lung Adenocarcinoma Mimicking CNS and Miliary Tuberculosis

Background: The radiological presentation of multiple ring-enhancing brain lesions with concurrent miliary pulmonary infiltrates is classically associated with disseminated tuberculosis (TB), often prompting empirical anti-TB treatment. However, such features may also mimic metastatic malignancy, particularly when microbiological evidence for TB is lacking. Case Presentation: We report a case of a 39-year-old previously healthy male who presented with a three-month history of constitutional symptoms, including weight loss, low-grade fever, non-productive cough, and headache. Imaging revealed miliary nodularity in the lungs and multiple intracranial ring-enhancing lesions, raising strong suspicion for disseminated TB. Despite comprehensive investigations—including multiple sputum studies, CSF analysis, EBUS-TBNA, and TB-PCR testing—no microbiological or histological confirmation of TB was obtained. The patient was treated empirically for CNS TB, but he deteriorated clinically and radiologically. After several multidisciplinary team (MDT) reviews, a supraclavicular lymph node biopsy revealed metastatic adenocarcinoma of pulmonary origin. Unfortunately, the patient succumbed to advanced disease shortly thereafter. Conclusion: This case underscores the diagnostic challenges in distinguishing disseminated TB from metastatic lung cancer when classical radiological findings are not supported by microbiological evidence. It highlights the critical importance of early histological confirmation, especially in TB-endemic regions or high-prevalence differentials, to avoid delays in appropriate cancer-directed therapy.