Lung adenocarcinoma with brain metastases presenting as unilateral weakness: A rare case report

Lung adenocarcinoma is a leading cause of cancer-related mortality worldwide, with brain metastases occurring in approximately 16%-20% of cases. These metastases typically present with non-specific neurological symptoms such as headache, seizures, and altered mental status. However, focal presentations such as unilateral limb weakness without respiratory symptoms are rare and diagnostically challenging, especially in resource-limited settings where such symptoms are frequently misattributed to stroke or central nervous system infections. We report the case of a 61-year-old Tanzanian woman with a history of hypertension who presented with new-onset seizures and left-sided hemiparesis. She was initially treated as a case of ischemic stroke at a regional hospital. Neurological examination revealed unilateral motor weakness, while brain CT and MRI showed multiple enhancing lesions in the cerebral hemispheres and basal ganglia. A chest CT scan revealed a mass in the left lower lung with bilateral nodules. Fine needle aspiration cytology confirmed primary lung adenocarcinoma. Notably, the patient had no respiratory symptoms at presentation. She was referred to oncology for palliative care. This case illustrates a rare and atypical presentation of metastatic lung adenocarcinoma with neurological symptoms in the absence of pulmonary complaints. Clinicians should consider brain metastases in the differential diagnosis of new- onset focal neurological deficits, even when classical respiratory symptoms are absent. Early neuroimaging and histopathological confirmation are essential to guide appropriate and timely management.