Additional diagnostic workup drawn a day prior to the 18F-FDG PET/CT became available showing positive EBV VCA-IgM and negative EBV VCA-IgG indicating acute infectious mononucleosis. CMV-IgM was furthermore positive. HIV and hepatitis panels were negative. Given the patient’s age, the clinical course with no past medical history and acute EBV titers, the patient’s abnormal 18F-FDG PET/CT scan was most likely secondary to acute EBV infection and no lymph node biopsy was performed. The patient was closely monitored. After a week he had resolution of symptoms clinically, ALT had increased to 461 U/L, LDH to 780 U/L. Twenty days after the initial 18F-FDG PET/CT scan the patient was feeling well, he had regained his appetite and returned to daily activities although still complained of tiredness. ALT = 193 U/L, LDH = 295 U/L. At this time both EBV VCA-IgG and EBV VCA-IgM antibodies were positive. CMV IgG was negative and CMV-IgM was borderline indicating a previous false positive CMV-IgM probably induced by the EBV infection. Follow-up 18F-FDG PET/CT scan in the patient performed 7 weeks after the initial scan (Figure 2) revealed complete metabolic response. Except for one lymph node which had decreased in size from 2.0 cm to 1.2 cm, all the other lymph nodes had regressed to normal size on CT. The size of the spleen had normalized (14 cm). ALT and LDH were normal. Reporting of this case is in accordance with the ethical standards of the institutional and/or national research committee. 18F-FDG uptake in EBV infection has been reported previously in a few cases in children [1] and organ transplant recipients [2]. Only two cases of 18F-FDG uptake in acute adult EBV infection have previously been reported [3,4]. In conclusion, this case illustrates acute adult EBV infection in a non-immunocompromised adult with EBV-induced lymphadenopathy that mimicked malignant lymphoma on 18F-FDG PET/CT scan. It highlights inflammation as one of the most well established causes of falsely interpreting 18F-FDG PET/CT as suspicious of malignancy. Any inflammatory process can demonstrate hypermetabolic activity because of the high degree of glucose metabolism by activated cells of inflammation [5,6]. As always, the benefits of 18F-FDG PET/CT in diagnostic work-up should be viewed in light of the radiation burden to the patient.