Abstract
RATIONALE: Large cell lung carcinoma (LCLC) is a rare undifferentiated malignant epithelial tumor of the lung. The diagnostic complexity of LCLC stems from its pronounced histological heterogeneity and diverse clinical presentation, particularly when extrapulmonary manifestations constitute the initial disease presentation, complicating early detection. PATIENT CONCERNS: A 58-year-old smoker presented with acute-onset dizziness, lethargy, and communication difficulties lasting 1 day. DIAGNOSES: The patient was admitted to the hospital, where extensive hypodense lesions in the right temporal, parietal, and occipital lobes were detected via cranial computed tomography, indicative of acute massive cerebral infarction. Histopathological examination revealed a pulmonary tumor with systemic metastases in the brain, heart, liver, and pancreas. Immunohistochemical staining showed undifferentiated pleomorphic cells that were negative for thyroid transcription factor-1, p40, synaptophysin, and CD56, confirming the WHO-defined null immunophenotype LCLC. Extensive cerebral metastases explained the acute neurological presentation. INTERVENTIONS: During the initial phase of the illness, the patient received intravenous edaravone (30 mg/d) and enteric-coated oral aspirin tablets (100 mg daily). On May 15, follow-up magnetic resonance imaging revealed acute multifocal infarcts involving the bilateral frontal-parietal lobes and the right temporo-occipital regions. This radiographic progression prompted escalation of therapy, including edaravone intensification, neuroprotection (cerebroprotein hydrolysate), and supportive care (intravenous infusion of 250 mL of 5% glucose solution containing 2 g calcium gluconate and 3 g vitamin C). OUTCOMES: The patient succumbed following a 2-month hospitalization during which acute cerebral infarction was the primary treatment focus. LESSONS: This case highlights LCLC's diagnostic complexity, aggressive metastasis, and potential for non-respiratory initial manifestations of LCLC. Early whole-body imaging and multidisciplinary evaluation are imperative to detect occult malignancies in unexplained stroke cases.