Abnormal nuclear structures (micronuclei, nucleoplasmic bridges, and nuclear buds) in a pleomorphic giant cell carcinoma of the stomach.

A rare case of pleomorphic giant cell carcinoma of the stomach in a 70-year-old man is reported. Characteristic microscopic findings included a general lack of architectural cohesiveness, aggregates of mononucleated or multinucleated giant cells, extensive areas of coagulative necrosis, and numerous mitoses. Immunohistochemically, tumor cells displayed cytoplasmic immunoreactivity for cytokeratin AE1/AE3 as well as overexpression of p53 and Ki-67. Electron microscopy revealed paranuclear tonofilaments bundles in giant cells confirming their epithelial nature. Furthermore, giant cells contained two or more nuclei with heterogeneous size, nucleoplasmic bridges, nuclear buds, and micronuclei. Similar abnormal nuclear structures have been closely related to breakage-fusion-bridge type of mitotic disturbances in tumor cell lines, and have not been previously reported in a human tumor.