Infectious mononucleosis in the elderly.

Infectious mononucleosis (IM) was diagnosed in four patients over the age of 50 years. Their age, absence of splenomegaly, lack of significant lymphadenopathy in three and an atypical presentation in one all contributed to a delay in the diagnosis. In two patients, in whom complications occurred, the Paul-Bunnell test was repeatedly negative. Confirmation of the diagnosis was made by the measurement of the Epstein-Barr virus IgM using differential sucrose gradient centrifugation. Because the presentation and clinical features of IM can be misleading in the elderly, we believe that a significant number of cases may go unrecognized.