Spontaneous rupture of the spleen detected on CT as the initial manifestation of infectious mononucleosis.

Spontaneous splenic rupture after infectious mononucleosis (IM) is a rare, potentially fatal complication of IM, occurring in 0.1-0.5% of patients with proven IM. It usually occurs several weeks after the onset of symptoms, but may, rarely, be the initial manifestation of the disease. The patient is usually examined as an emergency due to severe abdominal pain and a falling hematocrit. The radiologist should be aware of the pathologic conditions involving the spleen which may lead to its spontaneous rupture.