Figure 2

Histopathological findings. The tumor was predominantly composed of circumscribed cellular islands (A, 100×) comprised of large and small solid nests of polygonal cells that had moderate amounts of cytoplasm, and round to oval nuclei with minimal to moderate atypia (B, 400×). The mitotic cells were easy to find. The tumor cells widely expressed pan-cytokeratin, which appeared as typical dot-like positive on the nuclear side (C, 400×). CgA expression was patchy (D, 400×). Tumor cells exhibited partial strong AFP immunoreactivity with a granular pattern (E, 400×). Tumor cells focally showed strong HCG immunoreactivity (F, 400×). Transmission electron microscopic examination showed that the tumor cells contained electron-dense neuroendocrine granules measuring 230 nm in diameter (G).