Large-cell Neuroendocrine Carcinoma of the Lung with Carcinoid Syndrome

A 76-year-old woman was admitted to our hospital for refractory diarrhea with a poor antidiarrheal effect. Chest and abdominal computed tomography revealed a 24×22-mm mass in the left upper lobe of lung and multiple masses in the liver. Urine 5-Hydroxy indol acetic acid was markedly elevated. A liver biopsy revealed large-cell neuroendocrine carcinoma with serotonin production, suggestive of a lung origin, and a lung biopsy revealed combined large-cell neuroendocrine carcinoma and squamous cell carcinoma. Therefore, we made a definitive diagnosis of carcinoid syndrome caused by large-cell neuroendocrine carcinoma of the lung. Although chemotherapy was performed after diagnosis, the patient died 50 days postadmission.