Abstract
Histological and ultrastructural features of a pri-mary small cell carcinoma of the larynx were pre-sented. Lightmicroscopically, the tumor was compos-ed of small round cells with high nucleocytoplasm ratios. They were arranged in irregular sheats or nests. Immunohistochemically, most of the tumor cells were stained with antibodies to neuron specific enolase (NSE), and some were stained with antibo-dies to cytokeratin. Ultrastructurally, the tumor cells contained spherical dense core granules (neuro-secretary granules), approximately 100-500nm in dia-meter. The other cytoplasmic organellae were also well developed. Small cell carcinoma of the larynx must be differentiated from metastatic small cell carcinoma from other sites or undifferentiated squa-mous cell carcinoma. In our case there was no evi-dence of primary lesion in other regions. Further-more, immunohistochemical and ultrastructural exa-minations were useful for differential diagnosis.
