Caption |
The tumor, in this portion, shows epithelial and neuro-endocrine differentiation. One area of epithelial differentiation is characterized by the formation of a dilated tubule lined by a one cell-thick columnar epithelium reminiscent of the respiratory epithelium. However, most epithelial areas are composed of thick trabeculae and tubules lined by a pluristratified epithelium. These cells are polygonal to columnar and have a moderate amount of basophilic to acidophilic cytoplasm. Neuroendocrine-like areas are characterized by the formation of small nests composed of columnar to fusiform cells with a pale acidophilic cytoplasm. Mitotic index is high and numerous neoplastic cells undergo single cell necrosis. |