Extrapulmonary oat-cell carcinoma of the tongue: an electron-microscopic study.

An extrapulmonary oat-cell carcinoma arose in the tongue of a 62-year-old man who had a long history of cigarette smoking and ethanol ingestion. At presentation, he had the primary tongue lesion and cervical lymph-node metastases only, and search for a pulmonary primary was negative. Ten months later he died with metastases to liver, cerebrum, ribs, vertebrae, calvarium, and clavicle. Electron microscopy demonstrated cells with cytoplasmic processes and many dense-core neurosecretory granules that had a tendency to concentrate in the processes. Cells were linked by desmosomes. Electron microscopy is necessary for definitive diagnosis of extrapulmonary oat-cell carcinomas.