Neurocysticercosis mimicking cystic brain metastasis in a patient with lung cancer: a diagnostic pitfall

The coexistence of neurocysticercosis (NCC) and lung cancer in the same individual is relatively rare. Lung adenocarcinoma (LUAD) has a high risk of central nervous system metastasis. In the context of lung malignancies, the presence of multiple intracranial cystic lesions is often prioritized as brain metastasis. However, NCC can be highly mimicked by cystic brain metastases (CBM) on imaging, posing a significant diagnostic pitfall and potentially leading to unnecessary radiotherapy and chemotherapy, and delaying anti-cysticercosis treatment. We report a 71-year-old male patient with cognitive dysfunction as the initial symptom. Imaging showed a huge cystic brain lesion, and pathology confirmed the coexistence of NCC and lung mucinous adenocarcinoma (LMA), and a 58-month follow-up was completed. The patient ultimately died of leptomeningeal metastasis of lung cancer. This case suggests that when brain cystic lesions occur in tumor patients, infectious causes should be fully considered to avoid making treatment decisions solely based on imaging.