Which term describes a tumor that is well-differentiated and does not invade surrounding tissues?

• A. Malignant tumor
• B. Benign tumor
• C. Metastatic tumor
• D. High-grade tumor

Answer: (B)

A well-differentiated tumor that does not invade surrounding tissues is classified as a benign tumor. Benign tumors are typically composed of cells that resemble normal cells and maintain their functional characteristics. Because of their well-organized structure and limited growth, benign tumors generally do not spread to other parts of the body or invade nearby tissues, which is a defining characteristic of malignant tumors.

In contrast, malignant tumors exhibit uncontrolled growth and a tendency to invade surrounding tissues and structures. They often display poor differentiation, meaning their cells are not specialized and vary greatly from normal cells, which contributes to their aggressive nature and ability to metastasize to distant sites. Metastatic tumors arise when cancer cells spread from their original site to other areas in the body, signifying a more advanced stage of malignancy. High-grade tumors, on the other hand, refer to tumors that have a higher degree of abnormality and aggression, typically associated with poor prognosis. Thus, the characterization of a tumor as benign is directly linked to its well-differentiated nature and lack of invasive behavior.