Download Blood Cell ID: Common Peripheral Blood Cells (2014)

EDUCATIONAL COMMENTARY – BLOOD CELL ID: IDENTIFYING COMMON PERIPHERAL BLOOD
CELLS
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Pathology (ASCP). To obtain FREE CME/CMLE credits click on Earn CE Credits under Continuing
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paragraphs below. This will open a virtual image of the selected cell and the surrounding fields. If the
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Instructions.
Learning Outcomes
On completion of this activity, the participant should be able to:

describe the significant morphologic features of common peripheral blood cells.

discuss characteristics of red blood cell and platelet morphologic variations.
Case Study
A 78 year old female was seen in the emergency room for leg pain. The CBC results are as follows:
9
12
WBC=18.2 x 10 /L, RBC=3.43 x 10 /L, Hgb=10.1 g/dL, Hct=35.6%, MCV=103.8 fL, MCH=29.3 pg,
9
MCHC=28.2 g/dL, RDW=22.0%, Platelet=2615 x 10 /L.
Educational Commentary
The images presented in this testing event represent normal white blood cells and platelets that may be
seen in the peripheral blood. In addition, photographs of an abnormality in platelets and another with
erythrocytes are presented for educational review and discussion.
The cell in Image BCI-15 is a normal lymphocyte.
This is an example of a small lymphocyte, although
these cells are variable in size. Small lymphocytes
typically have a thin rim of blue cytoplasm. The
nucleus is usually oval, round, or slightly indented,
with clumped and dark purple chromatin.
American Proficiency Institute – 2014 3rd Test Event
EDUCATIONAL COMMENTARY – BLOOD CELL ID: IDENTIFYING COMMON PERIPHERAL BLOOD
CELLS (cont.)
Image BCI–16 shows an eosinophil. Note the
distinctive and numerous red-orange cytoplasmic
granules. These granules are usually large and
uniform in size. Often eosinophils are bilobed,
although that is not the case in this example. The
nuclear chromatin appears dense and stains purple.
Because eosinophils are normally present in small
numbers in the peripheral blood, it is not necessary to
classify them according to maturation stage.
Image BCI–17 identifies another type of granulocyte,
a basophil. As with eosinophils, basophils are present
in such small numbers in the peripheral blood that
they do not have to be classified based on stage of
maturation. The cell in this image is a typical basophil.
In contrast to eosinophils, the cytoplasmic granules in
basophils are dark purple, almost black. The granules
are often large, round, and characteristically so
numerous that they obscure the nucleus. Because
basophilic granules are also water soluble, they
sometimes appear faded or washed-out from the
staining process.
Basophils should not be confused with neutrophils containing toxic granulation or intracellular cocci
(bacteria). Toxic granules are smaller than the granules in basophils and do not overlay and hide the
nucleus as is typical for basophilic granules. Likewise, bacteria will be seen only in the cytoplasm of a
cell and will not obscure the nucleus. In addition, bacteria may appear not just as single organisms, but
sometimes in clusters or pairs. Often, bacteria may also be seen extracellularly, which can be helpful in
distinguishing them from other intracellular inclusions or granules. Another useful tip when trying to
decide the identity of a cell or an inclusion is to review other cells (or images) on the peripheral blood
smear. When suspecting toxic granulation or intracellular bacteria in a cell, look for other indications of
infection, such as Döhle bodies, vacuolization, and immature granulocytes.
American Proficiency Institute – 2014 3rd Test Event
EDUCATIONAL COMMENTARY – BLOOD CELL ID: IDENTIFYING COMMON PERIPHERAL BLOOD
CELLS (cont.)
Image BCI-18 illustrates a normal platelet. Platelets
originate from nucleated cells in the bone marrow
called megakaryocytes and represent cytoplasmic
remnants of these cells. Therefore, although platelets
lack a nucleus and are therefore technically not cells,
they can be called “cells” because of their derivation
from megakaryocytes. Platelets are small, generally
1 to 4 µm in diameter. Their shape may vary, but they
are usually round or oval. Platelets often appear
granular and stain blue-gray or light purple. The
platelet in this picture is morphologically typical.
Image BCI-19 shows a segmented neutrophil.
Segmented neutrophils characteristically have 3 to 4
nuclear lobes that are connected by strips of
chromatin. Sometimes, as in this example, the
chromatin filaments may be obscured. However, the
density of the chromatin and areas of parachromatin
suggest that this is a mature cell. The rule of thumb
when uncertain as to the maturation stage of a cell is
to classify the cell as the most mature stage. The
other typical feature of segmented neutrophils is the
numerous pink, tan, or violet-pink cytoplasmic
granules.
The arrow in Image BCI-20 identifies a giant platelet.
The term giant is used to define a platelet that is larger
than a normal red blood cell. Giant platelets may be
round, oval, or irregularly shaped. The edges of the
cell may be smooth, ruffled, or scalloped, as in this
example. The cytoplasm is usually a blue-gray or light
purple, like the color of a normal platelet. The cell may
have no granules or, as in this platelet, may have
numerous granules, either dispersed or in aggregates.
Giant platelets should not be confused with artifacts or
American Proficiency Institute – 2014 3rd Test Event
EDUCATIONAL COMMENTARY – BLOOD CELL ID: IDENTIFYING COMMON PERIPHERAL BLOOD
CELLS (cont.)
any type of nucleated cell. One type of artifact is the smudge cell, a leukocyte that has been
mechanically disrupted during the process of blood smear preparation, forming a fragile cell. The name
originates from the “smudge” appearance that results when the cytoplasm disintegrates and is stripped
away, leaving only nuclear material. Smudge cells have no defined size or shape, although they are
often as large as or larger than white blood cells. They are often lymphocytes, because these cells are
particularly susceptible to physical trauma during smear preparation. Therefore, smudge cells are a
common finding in chronic lymphocytic leukemia. Likewise, smudge cells have no granules and stain
red-purple.
In addition, giant platelets should be distinguished from nucleated cells such as megakaryocytes and
monocytes. The concentration of granules in the center of this giant platelet suggests a nucleus.
However, there is no nuclear membrane and the staining color is not the dark purple typically associated
with nuclear chromatin. In fact, the overall color of this cell is similar to other platelets seen in the image.
Therefore, this giant platelet should not be confused with any nucleated cell, such as a megakaryocyte or
monocyte.
Image BCI-21 identifies a spherocyte. Spherocytes
have a decreased surface to volume ratio because
they have lost membrane. Therefore, they are smaller
than normal red blood cells, are dense, and lack any
area of central pallor. Spherocytes are most often
seen associated with hereditary spherocytosis,
immune-mediated hemolytic anemia, and
microangiopathic hemolytic anemias. However, as the
underlying mechanism resulting in thrombosis is not
specified in this case study patient, identifying a
spherocyte on the peripheral blood smear can be
clinically significant. Also note that if the entire smear is scanned using API’s ImageViewer, many
examples of other spherocytes as well as the giant platelet previously described may be seen.
Summary
This testing event presented images of normal and abnormal peripheral blood cells. Identification of
these cells involves a systematic process evaluating all morphologic features of cells, including overall
cell size, nuclear characteristics, and cytoplasmic appearance. Appropriate identification and
classification of cells provides important information to help the clinician determine a diagnosis.
© ASCP 2014
American Proficiency Institute – 2014 3rd Test Event