Infectious mononucleosis in hospitalized patients over forty years of age.

Clinical and laboratory features of 17 patients over 40 years of age (mean age: 55 years) admitted with infectious mononucleosis were compared with those of 17 adolescents (mean age: 13 years) hospitalized with this illness. Elderly patients with infectious mononucleosis were found to run a longer febrile course (13 vs. 7 days, p less than 0.01) and to have a lower peak total white blood cell count (6,600/mm3 vs. 11,000/mm3, p less than 0.001) and a lower incidence of splenomegaly (50% vs. 76%, p less than 0.05), lymphadenopathy (25% vs. 94%, p less than 0.001), and pharyngitis (25% vs. 47%, p less than 0.05), compared with young patients with infectious mononucleosis. Patients in both groups had a high prevalence of abnormal liver function tests. It is concluded that infectious mononucleosis in patients over 40 years of age is not as uncommon as previously reported, and that clinical and laboratory features differ between young and older patients suffering from this disease.