What does the term "pleomorphism" refer to in pathology?

In pathology, the term "pleomorphism" specifically refers to variation in cell shape and size. This characteristic is often observed in neoplastic tissues and can indicate the presence and severity of a disease, particularly cancer. The presence of pleomorphism can suggest that a tumor is more aggressive and may have a different prognosis compared to tumors with homologous or uniform cellular characteristics.

Pleomorphic cells can vary significantly in appearance, which may include differences in the size of the nuclei, the cytoplasm, and the overall shape of the cells. This heterogeneity in cellular appearance is often associated with malignancy, as cancer cells undergo genetic changes that allow them to diverge from their normal counterparts.

Memorable examples of pleomorphism can be found in certain types of tumors, such as anaplastic carcinomas, where the cells exhibit significant variations indicating a high grade of malignancy, often leading to poorer outcomes.

In contrast to pleomorphism, uniform cell characteristics would indicate a more organized appearance typical of benign lesions or well-differentiated tumors. Inability to respond to treatment and rapid cell death do not define pleomorphism and refer instead to other aspects of tumor biology and behavior.