A Tale of Two Diagnoses: Pulmonary Tuberculosis and Metastatic Lung Adenocarcinoma in a High-Risk Host

Tuberculosis (TB) and lung cancer are major global health burdens, often coexisting in high-risk populations such as smokers and immigrants from TB-endemic regions. We present a diagnostically complex case of a 57-year-old Filipino male with a chronic cough and a right upper lobe lung mass initially suspected to be TB. Imaging revealed spiculated nodules and widespread adenopathy, raising concern for malignancy. Although the initial biopsy was inconclusive, <i>Mycobacterium tuberculosis</i> was confirmed by polymerase chain reaction (PCR), and the patient was started on rifampin, isoniazid, pyrazinamide, and ethambutol (RIPE therapy). A repeat lymph node biopsy revealed metastatic lung adenocarcinoma with high PD-L1 expression (80%). He was treated sequentially with pembrolizumab followed by combination chemo-immunotherapy after disease progression. The patient tolerated treatment well, aside from nausea and an unrelated posterior cerebral artery infarct. This case underscores the diagnostic overlap and management challenges of coexisting TB and lung cancer and highlights the need for a multidisciplinary, staged approach in high-risk individuals.