Spontaneous mononucleosis caused by cytomegalovirus in the immunocompetent adult

BACKGROUND: The first Spanish series of spontaneous infectious mononucleosis (IM) by cytomegalovirus (CMV) in immunocompetent adults is reported. METHODS: Patients whose clinical manifestations, physical exam, analysis and serology were compatible with acute CMV infection from 1984 to 1993 were retrospectively reviewed. RESULTS: Thirty patients with a mean age of 36 years fulfilled the diagnostic criteria. All presented fever, alone or associated with other symptoms, with a mean duration of 18 days, which persisted over 3 weeks in 36%. Physical exam showed lymph node enlargement (50%), hepatomegaly (33%), splenomegaly (20%) and was normal in 8 patients (26%). Mean leukocyte count was 9.75 x 10(9) (+/- 4.63 x 10(9) with more than 50% lymphomonocytic cells in 22 patients (76%) and reactive lymphocytes, principally from the outset, although this was observed on days 2 and 60 in 11 cases (36%). LDH, ASAT and ALAT were moderately elevated and ESR was normal. Serologic diagnosis was established from IgM (13%) seroconversion or positive IgM in the two samples with IgG four-fold increase (23%), as well as the presence of positive IgM and invariable high IgG in both determinations (26%) or all IgM positive titers in a single sample (36%). CONCLUSIONS: Infectious mononucleosis by cytomegalovirus is an infrequently diagnosed disease which should be considered in any young patient with fever despite a little demonstrative initial physical exam absence of atypical lymphocytes or a lack of diagnostic serology.