Q & A, 5/13

References

1. College of American Pathologists Commission on Laboratory Accreditation. Chemistry and Toxicology Checklist. Sept. 25, 2012 edition. Northfield, Ill.: College of American Pathologists.

Anthony Killeen, MD, PhD
Director of Clinical Laboratories
Department of Laboratory Medicine and Pathology
University of Minnesota Medical Center
Fairview, Minneapolis

Chair, CAP Instrumentation Resource Committee Member,
CAP Council on Scientific Affairs

[pulledquote]Q. How should smudge cells present on peripheral smear review be handled in reporting results? Should albumin preparation be performed each time the smudge cells are present in an individual patient with known smudge cell results? Should the smudge cells be counted as lymphocytes in a peripheral smear manual differential, or should smudge cells be reported as a gradient 1+, 2+, and so on, or just as present? What is the general practice carried out in most laboratories? [/pulledquote]

A. Smudge, or basket, cells are the remnant of a fragile cell that has been damaged in the process of making a blood smear. Most commonly these cells are lymphoid in nature. Precise lineage assignment cannot be done, as the cell is not intact. The “smudge” is condensed nuclear material without identifiable cytoplasm. This artifact can be avoided by adding a drop of serum albumin to four to five drops of blood before making the blood smear. Smudge cells are most commonly seen in disorders characterized by lymphocyte fragility, such as chronic lymphocytic leukemia (CLL) and infectious mononucleosis.

Most laboratories do not report smudge cells in the white blood cell differential, but do note the presence of smudge cells. Ideally, albumin is added to the blood and the white blood cell differential is performed using the albumin smear. Smudge cells should not be assumed to be lymphocytes, and thus a manual differential should be performed only on intact leukocytes. Red blood cell morphology, however, should be reported using the smear prepared without albumin, because albumin will alter the erythrocyte morphology.

In some laboratories, grading of smudge cells is performed in patients with known CLL. In an informal survey of CAP Hematology/Clinical Microscopy Resource Committee members, all laboratory directors recommended that the presence of smudge cells be noted, but none of the members graded smudge cells. However, a literature search reveals that in some laboratories the percentage of smudge cells may be a prognostic factor in CLL. Your laboratory’s policy on smudge cells will also depend on whether your hematologist/oncologists find this information useful in the setting of chronic lymphocytic leukemia; discussions with your institution’s hematologist/oncologists will clarify this point.

References

1. Johansson P, Eisele L, Klein-Hitpass L, et al. Percentage of smudge cells determined on routine blood smears is a novel prognostic factor in chronic lymphocytic leukemia. Leuk Res. 2010;34(7):892–898.
2. Nowakowski GS, Hoyer JD, Shanafelt TD, et al. Percentage of smudge cells on routine blood smear predicts survival in chronic lymphocytic leukemia. J Clin Oncol. 2009;27(11):1844–1849.
3. Paydas S. Smudge cells: very old history and new conclusions. Leuk Res. 2010; 34(12):1680.

Tracy I. George, MD
Associate Professor of Pathology
Chief, Hematopathology Division
University of New Mexico Health Sciences Center
Albuquerque

Advisor, CAP Hematology/Clinical
Microscopy Resource Committee
Member, CAP Council on Scientific Affairs