Tuberculosis meningoencephalitis mimicking lung cancer with metastasis: a case report.

This case report describes a 73-year-old male with gait disturbance and headache, presenting with widespread necrotic and contrast-enhancing brain lesions alongside lung nodules. Initial differential diagnosis strongly favored lung cancer metastasis due to these findings. Despite largely negative cerebrospinal fluid and molecular tests, systemic evaluation with positron emission tomography-computed tomography showed increased fluorodeoxyglucose uptake in both lung and lymph nodes, further suggesting malignancy. However, a crucial neck lymph node biopsy ruled out cancer. Empirical antituberculosis therapy led to significant clinical improvement, though subsequent brain imaging revealed a paradoxical reaction. This case provides a striking example of the diagnostic dilemma of differentiating tuberculous meningoencephalitis from metastatic lung cancer, emphasizing the critical roles of clinical suspicion, biopsy, and understanding paradoxical responses in challenging presentations.