What diagnosis do atypical lymphocytes point to?

Atypical lymphocytes are often associated with infectious processes, particularly viral infections such as Epstein-Barr Virus (EBV), which is the causative agent of infectious mononucleosis. In the context of EBV infection, atypical lymphocytes are typically larger and have more irregular shapes compared to normal lymphocytes. These atypical cells are indicative of an immune response to the viral infection, as the body produces a unique type of lymphocyte to combat the virus, resulting in the distinct morphology observed under the microscope.

While atypical lymphocytes can be present in other hematological conditions, their strong association with EBV-related mononucleosis makes it the most relevant diagnosis in this context. In cases of acute lymphoblastic leukemia or chronic lymphocytic leukemia, other clinical signs, laboratory findings, and cellular characteristics would be more diagnostic. Non-Hodgkin's lymphoma may exhibit atypical lymphocytes as well, but the clear link of these lymphocytes to issues of infectious mononucleosis provides a stronger rationale for this diagnosis in the setting described.