Lung Metastasis from an Immature Teratoma of the Nasal Cavity Masquerading as Small Cell Carcinoma of the Lung

We report a case of small cell lung cancer that turned out to be a metastatic teratoma from the nasal cavity rather than a new primary cancer. A 54-year-old woman was diagnosed with an immature teratoma of the nasal cavity with a predominant neuroblastomatous component. Small cell lung cancer was detected by bronchoscopic biopsy 21 months later, and it was treated with concurrent radiochemotherapy as if it had been a new primary cancer. Since a recurrent tumor containing fat-like density grew slowly on the serial chest CT scans after achieving complete response, we reached the conclusion that the small undifferentiated cells could be metastatic neuroblastomatous components from the immature teratoma of the nasal cavity.