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New York State Department of Health - Wadsworth Center - Cytohematology Proficiency Testing

Slide 154 [100X]        Click here for a higher resolution image.

This slide was taken from a case of infectious mononucleosis, the arrowed cell is a reactive/atypical lymphocyte (code: 11).  The lymphocytes present in the field are reacting to an abnormal stimulus and as a result are similar in appearance to each other. The characteristic amoeboid basophilic cytoplasm partially surrounds adjacent red blood cells and displays darker staining in the peripheral margins. Thirty-two percent of the participants identified this cell as a monocyte, although the morphological features of the cells are more characteristic for reactive/atypical lymphocytes.

Due to lack of consensus by participants, pass credit was assigned.

Number of Responses

Percent of Laboratories

Cell Code and Type

214

50.0%

Code 11: Reactive/Atypical lymphocyte

137

32.0%

Code 12:  Monocyte

26

6.1%

Code 01:  Blast cell, not classified

24

5.6%

Code 23:  Lymphoma / Sézary cell

14

3.3%

Code 06:  Myelocyte

6

1.4%

Code 10:  Normal lymphocyte

4

0.9%

Code 07:  Metamyelocyte

1

0.2%

Code 17:  Smudge cell / Basket cell

1

0.2%

Code 05:  Promyelocyte

1

0.2%

Code 04:  Monoblast

Return to January 2003 Proficiency Test Event