5 March 2025 (Wednesday) - Atypical Lymphocytes

The nice people at the American Society of Hematology sent me this article today. A review of atypical lymphocytes.

If there’s one thing I see all the time it is atypical lymphocytes. On reflection I describe them by waving my hands in the air and using swear words. This article rather consolidates what I know and gives it some formal grounding.

Feature	Reactive	Malignant
Patient’s age	<30	>50
Lymphadenopathy	Typically absent	May be present
Absolute lymphocyte count	Usually increased	Increased, normal, or decreased
Percent lymphocytes	Usually increased	Increased, normal, or decreased
Platelets	Normal	Normal or decreased
Anemia	Absent or mild	Usually present
Cell heterogeneity	Present	Absent
Cell size	Variable but usually large	Small to medium to large
Nucleus	Irregular	Round, indented, folded, irregular
Nucleolus	Absent or inconspicuous	Absent, prominent
Cytoplasm	Abundant, radiating basophilia	Scant to moderate
Cytoplasmic projections	Absent	May be present *
Red blood cell molding	Present	Usually absent
Smudge cells	Absent	May be present **