In patients with infectious mononucleosis, abdominal pain is usually a
ttributed to visceral enlargement. A teenage girl with symptoms of app
endicitis was found at laparotomy to have mesenteric adenitis. Postope
ratively, she developed classic features of Epstein-Barr virus (EBV)-i
nduced mononucleosis. The lymphoproliferation characteristic of EBV in
fection can cause severe localized abdominal pain that predates the on
set of mononucleosis.