ABSTRACT
Purpose To study the clinicopathologic characteristics,immunophenotype and Epstein-Barr virus (EBV) infection in infectious mononucleosis (IM),and to enhance the knowledge and diagnosis of the disease.Methods The clinical data,laboratory examination,and lymph nodes biopsy of 9 cases of IM were collected.Immunohistochemistry of EliVision twostep,flow cytometry and EBER in situ hybridization double labeling were studied in 9 cases.Relevant literatures were also reviewed.Results The average age of 9 cases of IM was 22 years old.Patients presented with acute onset,short disease duration,fever,and liver,spleen and lymph node enlargement,and increased abnormal lymphocyte.Also,it was positive in the antiEBV VCA-IgM detection.EBV-DNA copy numbers were all increased.Most WBC counts were increased.Liver function index was abnormal.The ratio of peripheral blood lymphoeytes obviously increased and the ratio of atypical lymphocyte was greater than 10％.Immunophenotype of peripheral blood flow cytometry was characterized by high expression of T cells markers and CD8.CD4 expression was significantly reduced or even not expressed.CD4+/CD8 + ratio was reversed.Lymph nodes were destroyed in different extent and presented mottling without the thickening of the capsule and interstitial fibrous hyperplasia.B cells differentiation spectrum was visible.The lesion cells were mostly CD3-positive cells.CD20,CD30-positive activated cells and immunoblast cells diffused distribution and showed different degrees of strength.The site of EBER in situ hybridization was mainly in T region.Conclusion IM is an EBV-related acute self-limiting lymphoproliferative disease.Taking clinical characteristics,morphology,EBV infection and immunophenotype into considerations will help to correct diagnoses.