What is typically a characteristic of high-grade tumors?

High-grade tumors are often characterized by high cellular pleomorphism, which refers to significant variation in the size, shape, and appearance of the tumor cells. This pleomorphism is indicative of the aggressive nature of these tumors and their higher degree of anaplasia, which means that the cells exhibit abnormal features compared to normal cells. The marked variability in morphology reflects the tumor's poor differentiation and increased potential for rapid growth and invasion into surrounding tissues.

In contrast, low-grade tumors typically present with less pleomorphism and more uniform cell structures. Therefore, the presence of high cellular pleomorphism serves as an important histopathological feature in the assessment of tumor grade and prognosis.