Atypical infectious mononucleosis in the cervical region mimicking lymphoma in an adult: a case-based literature review

Background: Infectious mononucleosis (IM) is an infectious clinical entity commonly seen in adolescence and early adulthood. It is caused in the majority of cases by Epstein-Barr virus (EBV) and it presents as pharyngitis, fever, and lymphadenopathy. As the viruses mainly target the lymphocytes and reticuloendothelial system of the body, leading to the proliferation of the lymphatic tissues, it is often mistaken as lymphoma. Most cases of IM can be easily distinguished from lymphoma by clinical presentations and laboratory findings. However, atypical clinical presentations or laboratory findings occasionally occur, including the ages of patients over 30, generalized or isolated lymphadenopathy at unusual sites, negative heterophile antibody tests, absence of atypical lymphocytosis in the peripheral blood smear, etc. These atypical cases may lead to confused diagnosis. Therefore, IM should be differentiated from malignant lymphoma. In this paper, we reported a case of atypical IM in the cervical region of an adult, with elder age and longer disease course than typical IM.Case presentationIn this paper, we reported a case of IM in the cervical region of a 31-year-old man, and reviewed the recent literatures on the pathogenesis, as well as differential diagnosis of IM.ConclusionWhen facing enlarged tonsil or cervical lymph nodes, the pathologists should increase vigilance to the differential diagnosis between infectious diseases and lymphomas. Especially in ambiguous cases, it is essential to test for EBER by in situ hybridization to rule out IM before making a preliminary diagnosis of lymphoma.