[Coexistence of lung cancer, brucellosis, and tuberculosis in a single patient: a case report].

Lung cancer, pulmonary tuberculosis, and brucellosis are common clinical diseases. They share overlapping clinical manifestations and pulmonary imaging findings, and all may involve multiple organ systems, making differential diagnosis challenging. We reported a rare case of lung cancer, and co-infection with pulmonary tuberculosis and brucellosis. A 57-year-old male was admitted to our hospital, presenting with intermittent fever for 7 months and cough accompanied by shortness of breath for 1 month. He had previously sought medical care at multiple hospitals, where he was diagnosed with brucellosis and suspected of having pulmonary tuberculosis. Despite receiving anti-tuberculosis and anti-brucellosis treatments, his pulmonary imaging abnormalities and dyspnea progressively worsened. Pathological examination of mucosal biopsies obtained via bronchoscopy and cervical lymph node biopsy at our hospital confirmed squamous cell lung carcinoma. Metagenomic next-generation sequencing of bronchoalveolar lavage fluid detected <i>Mycobacterium tuberculosis</i>. Although his pulmonary condition temporarily improved following standardized anti-tuberculosis treatment and chemotherapy for lung cancer, the lung cancer subsequently progressed, and the patient ultimately died.