Smudge cells

Appearance:
Smudge cells are formed when lymphocytes rupture during the preparation of a blood film. These damaged cells are not usually counted. Since damaged lymphocytes often occur in chronic lymphocytic leukemia, they are classified separately in the differential blood count.

Occurrence:
Smudge cells are seen in chronic lymphocytic leukemia, in reactive lymphocytosis (e.g. CMV infection), and other lymphoproliferative processes.