Undifferentiated carcinoma of the parotid gland with bizarre giant cells. Clinicopathologic report with ultrastructural study.

A rare autopsy case of undifferentiated carcinoma of the parotid gland with bizarre giant cells is reported. Grossly, the tumor was fist-sized, firm, solid, grayish-white in color, and was not encapsulated, with a bean-sized ulceration on the skin. Microscopical examination revealed undifferentiated carcinoma of the parotid gland composed of bizarre giant cells, large tumor cells, and spindle cells in part. Ultrastructural examination, recovered from formalin-fixed material, disclosed filamentous structure in some large tumor cells. It is strongly suggested that myoepithelial cells played an important role in the development of the undifferentiated carcinoma of the parotid gland. The clinical and histopathological characteristics of this case is described, and the literature concerning undifferentiated carcinoma of the parotid gland is reviewed.