Abstract
We report a case of infectious mononucleosis initially presented with lymphoma-like features. Examinations revealed abdominal ascites, splenomegaly, elevated lactic dehydrogenase, extensive lymphadenopathy from neck to the mediastinum, and a high 18F-fluoro-2-deoxy-D-glucose uptake pattern on positron emission tomography scan. The impression of lymphoma could not be ruled out based on the clinical manifestations, most importantly the diffuse necrosis with focal monotonous pattern and a high Ki-67 proliferation index found on pathological examination. Our presentation emphasizes the potential challenge in misdiagnosis of advanced infectious mononucleosis. Knowledge of its unusual clinical features is therefore essential to avoid misdirected interventions when it mimics diseases like lymphoma.