Which organ can be affected by mononucleosis?

Mononucleosis primarily affects the spleen, which can become enlarged due to the infection caused by the Epstein-Barr virus. In some cases, the liver may also be affected, leading to mild liver inflammation. Symptoms can include fatigue, sore throat, and swollen lymph nodes, but the spleen's enlargement is a notable concern as it can increase the risk of rupture.