Figure 1
Case 1: (a) The tumor cells appeared to be lining an irregular space and a papillae-like structure (center). There is marked pleomorphism of the neoplastic cells, some of which are multinucleated. Two mitotic figures can be seen in the center of the figure. (b) Higher magnification of the neoplastic cells, many of which are multinucleated. The cytoplasm is abundant and the nuclei often exhibit clumped chromatin. Two mitoses are present in the upper left corner of the figure. (c) Immunohistochemical preparations showing diffuse strong positivity for pan-keratin in the cytoplasm of the neoplastic cells. (d) Strong keratin expression can be seen in both mononucleated and multinucleated tumor cells.
