Smudge cells – include or exclude?

Increased focus is placed on the importance of smudge cells in connection with certain types of diagnoses.

A number of articles explore this subject and according to the article Percentage of Smudge Cells on Routine Blood Smear Predicts Survival in Chronic Lymphocytic Leukemia the writers suggest that the number of smudge cells may have important biologic correlations rather than being only an artifact of slide preparation.

Smudge Cells or Basket Cell-A Diagnostic Pitfall reviews that the smudge cells on the film will not be included in manual differential, thereby resulting in an undercounting of the actual lymphocytes present. So education is needed.

This is an interesting discussion and we would like to find out how your policies and routines look like when it comes to smudge cells.

Do you include the smudge cell in the differential? If yes when and why?

Smudge _cells

21 thoughts on “Smudge cells – include or exclude?”

  1. No. We make an albumin slidesmear to strengthen the smudge cells so that the cells can maintain cellular integrity for identification and then perform the differential.

    1. We also make albumin smears on any patient with significant number of smudge cells. We report our differential from the albumin smear, and our RBC/Platelet morphology from the original smear.

  2. Smear cells must always be included in the differential count or the absolute count of all cell types will be wrong. If the type of cell is obvious, as in chronic lymphocytic leukaemia, then the cells should be counted as that cell type. If their nature is not certain they should be assigned to a separate category, e.g. ‘other’ or ‘unidentified’. However, if the reason for excessive smear cells is that the blood specimen has spent too long in transit then no differential count should be attempted and no opinion should be given on the blood film.

    1. I totally agree with Barbara Bain. We have for years had a separate category for this kind of cells called “Smudge cells” – in blood and – soon – in Body Fluids. The reason is, that we use other/Unidentified for other kind of cells, which we will comment on.

    2. Thank u dr Bain.
      U mean if we know that the origin of smudge cells are lymphocytes, we include them with lymphocytes, without writing any comment in the report?

  3. Automated differential count is best method. Analyzer print may flag “Lymphocytosis”. It depends upoun your laboratory policy to make slide. I would like to make slide and review. However, if manual slide is needed and found significant number of smudge cells, prepare albuminized slide. Most of the time, it works.

  4. And I do agree, that if it is possibly (in “normal” CLL-samples) it is best to report the numbers from the automated differential from the cell counters (where smudge cells do not excist) .
    We hope to have a smoother workflow, when we start to use SYSMEX XN, and will then consider that possiblilty.

  5. If we have a fresh sample, we always try to minimize the number of smudge cells (if they exceed 20% ) by adding Albumin and make the slide manually. This often helps but not always.

    If the % of smudge cells >10% we include the smudge cells in the WBC-diff and quantify them (they have their own cell-type).
    We are about to change this procedure, so that we always will report the number of smudge cells, if they excist (which they often do) . The same rule will apply to smudge cells in Body Fluids as well. (They will have their own cell-type there too).

    Smudge cells are importent to report, because they also tells something about the uncertainty of the differential count. It is often lymphocytes – or blastcells – but in samles from children, we often see neutrophiles appear as smudge cells.
    RIght now we are validating a DIff Spin2 (slide spinner) which looks very promising (fewer smudge cells). But unfortunately this instrument is not produced any more.

  6. In most cases in our lab we take the automated differential off our cell counters as this is the most accurate count. If we do a CellaVision or manual diff and there are significant numbers of smear cells we count them in the differential. If we require an accurate manual differential we may do an albumin film but this is very rare. The automated differential is the most accurate and efficient option.

  7. We report smudge cells as an absolute value when patient is a known CLL and smudge cells are > 10%. When patient history is unknown we make an albuminized slide and report out the differential with a comment ” differential performed on an albuminized slide due to smudge cells present”.

  8. We prepare and albumin treated slide in the event smudge cells are observed. However, the resultant cells the are preserved generally have abnormal morphology. We do not encounter a lot of non-lymphocytic smudge cells.

  9. We should also consider that not all smudge cells, or bare-nucleus, were lymphocytes. Smudge cell presence in a case of CLL makes sense and is expected, but what if we report smudge cells on a newborn slide? Does that indicate that the reported % lymphocyte is falsely decreased? Not necessarily. Perhaps the cells that smudged were not lymphocytes. I think reporting smudge cells without any further resolution is a way of the past. Current laboratory excellence should include resolution of smudge cells and a differential that is accurate because a new slide was made that does not contain smudge cells.

  10. I agree with Warry van Gelder and Sherry Ippolito: the automated differential count is more reliable than the manual differential when significant smudge cells are present (approximately 10% or more). We rarely rely on a manual differential, but when we do, we always prepare an albumin smear with the minimum amount of albumin to keep the smudges intact. We use 1 drop of 10% albumin to 5 drops of blood. The lower the albumin concentration, the better the preservation of abnormal morphology.

  11. My belief is that the presence of smudge cells, in either fresh or old blood, equals an inaccurate leukocyte differential. The only cell that can be accurately identified when smudged is an eosinophil because of the spilling of the orange granules. It is essential to remake the smear to remove the smudge cells and acquire and accurate differential. In the case of old blood, no resolution is possible except for a redraw; however, with fragile lymphocytes or other cells, adding a small amount of albumin (from the blood bank) to the drop of blood prior to smearing gives the fragile cells the protection they need to survive the glass-to-glass forces. An accurate leukocyte differential can be obtained from this slide.

  12. Smudge cells are included in the report only as slight, moderate, or many. Our CellaVision interface is set up to translate the number of smudge cells classified into slight, moderate, or many.

  13. We report the presence of smudge cells separately, but do not quantify the number of smudge cells. Whether you take the percentage smudge cells into account when reporting the percentage of lymphocytes, depends on which result you report. In general, the hematology analyser will have no problems counting lymphocytes in case of a CLL. Therefore a reliable estimate of the absolute number (or percentage) of lymphocytes is readily available.
    As for the link between the number of smudge cells in CLL and survival: it will be a major challenge to compensate for different techniques to preparae smears and the outcome of this study.

  14. Make an albumin smear to perform a manual differential. Albumin will most likely prevent the cells from smudging when the smear is made. Then just report the smudge cells as present.

    1. We don’t include smudge cells but a comment is added to the report ( ex. Few smudge cells noted on original smear). Differential count is performed on a slide prepared from a sample with a drop of 20% albumin to prevent smudging of cells.

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