Anaplasia is characterized by which of the following?

Anaplasia is characterized by the loss of differentiation in cells. This refers to a process where the cells become less specialized and primitive in their functions and appearance compared to normal cells. In anaplastic cells, there is often a marked deviation from the original tissue structure, and they may exhibit increased pleomorphism, meaning they vary in shape and size. These cells typically lose the specific characteristics that define their normal counterparts, resulting in a more stem-like or unspecialized state. This loss of differentiation is a hallmark of malignancy, as it indicates aggressive behavior and a tendency for uncontrolled growth.

The other options describe different cellular changes. Replacement of cell types that are usually not present refers more to metaplasia or a process of transformation rather than anaplasia. An increase in the number of cells is indicative of hyperplasia, which involves a more normal pattern of cell growth and proliferation, often in response to a stimulus. Enlargement of cells typically describes hypertrophy, which is the increase in cell size rather than a loss of differentiation. These distinctions reinforce why loss of differentiation is the defining characteristic of anaplasia.