Question: what are the atypical lymphocytes in infectious mononucleosis?
Answer: Atypical lymphocytes are shown here. These WBC's are "atypical" because they are larger (more cytoplasm) and have nucleoli in their nuclei. The cytoplasm tends to be indented by surrounding RBC's. Such atypical lymphocytes are often associated with infectious mononucleosis from Epstein-Barr virus (EBV) infection.