Which organ typically enlarges during infectious mononucleosis?

During infectious mononucleosis, the spleen is the organ that typically enlarges. This condition is often caused by the Epstein-Barr virus (EBV), which primarily affects lymphoid tissue. The spleen is a crucial part of the lymphatic system, responsible for filtering blood, storing blood cells, and playing a significant role in the immune response.

In mononucleosis, the infection triggers an immune response that leads to lymphoid hyperplasia, specifically in the spleen. This results in splenomegaly, or the enlargement of the spleen. The other organs mentioned, while they can be affected in some infectious processes, do not typically enlarge specifically in the context of infectious mononucleosis. The liver may show some enlargement or changes due to the overall infection but is not as consistently affected as the spleen in this specific condition. Similarly, the kidneys and heart are not primary organs impacted by mononucleosis, maintaining their normal size in response to this type of infection.