What physical exam finding is common in patients with infectious mononucleosis?

Enlarged lymph nodes are a hallmark physical exam finding in patients with infectious mononucleosis, primarily caused by Epstein-Barr virus (EBV). During the illness, the lymphatic system responds to the infection, leading to lymphadenopathy, which is often most pronounced in the posterior cervical region. This swelling is a result of the immune response, involving the activation and proliferation of lymphocytes and other immune cells to combat the viral infection.

The presence of enlarged lymph nodes, in conjunction with other symptoms such as fever, sore throat, and fatigue, helps healthcare providers establish a diagnosis of infectious mononucleosis. In contrast, while a rash can occasionally be seen, especially if patients are treated with certain antibiotics, it is not as prevalent or characteristic as lymphadenopathy. Pneumonia is unrelated to infectious mononucleosis and typically would indicate a different infectious process altogether. Abdominal pain may occur in some cases due to splenomegaly, but it is not a defining feature compared to the prominent lymph node enlargement characteristic of this disease.