MLAB 1415: HematologyKeri Brophy-Martinez

AnemiaPart Three

RBC Shape VariationsAlterations in the shape of the

RBC is called poikilocytosis.

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Target Cells (Codocytes) Occur due to an

increased red blood cell surface area.

Appear as "targets" on peripheral blood smear.  Have a pale central area with most of the hemoglobin around the rim of the cell.

Are always hypochromic.

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Target Cells (Codocytes)

Mechanism in formation is related to excess membrane cholesterol and phospholipid, and to decreased cellular hemoglobin. 

Osmotic fragility is decreased.

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So what is Osmotic Fragility?It is a test to measure RBC

resistance to hemolysisThe quicker the hemolysis

occurs, the greater the osmotic fragility

What affects osmotic fragility?◦Surface to volume ratio◦Cell membrane permeability

Target Cells (Codocytes) Seen in patients with:

◦ Liver disease ◦ Hemoglobin C Disease or Trait ◦ Post-splenectomy ◦ Iron Deficiency Anemia ◦ Any Hemoglobin Abnormality◦ Can be artifactual

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Spherocytes

Have a low surface-to-volume ratio.

Smaller than normal red cell; hemoglobin relatively concentrated; and, have no area of central pallor.

Shape change is irreversible.

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SpherocytesSeveral

mechanisms for formation, but all involve loss of membrane; aging, antibody coating or genetic defect

Is the final stage for red cells before they are sequestered in the spleen.

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SpherocytesSeen in patients with:

◦Activated complement ◦Immune Hemolytic Anemia ◦Hereditary Spherocytosis ◦Post-Transfusion

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Wait! What is Complement?Complement refers to a complex set

of 14 distinct serum proteins that are involved in three separate pathways of activation.

Major Functions◦Promote the inflammatory response

by opsonization which enhances susceptibility of coated cells to phagocytosis.

◦Alter biological membranes to cause direct cell lysis.

Ovalocytes and Elliptocytes

Ovalocytes may appear normochromic or hypochromic; normocytic or microcytic.

Hemoglobin concentrated at both endsExact mechanism of formation unknown.

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Ovalocytes and Elliptocytes

Ovalocytes associated with: ◦ Myelodysplastic

Syndromes ◦ Thalassemias ◦ Megaloblastic Processes

Elliptocytes associated with:◦ Iron Deficiency Anemia ◦ Hereditary Elliptocytosis ◦ Idiopathic Myelofibrosis

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StomatocytesRed cell of

normal sizeSlit-like central

area of pallor Exact

mechanism of formation unknown

Usually artifactual

Increased osmotic fragility

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StomatocytesAssociated with following disorders:

◦ Hereditary Stomatocytosis ◦ Hemolytic, Acute Alcoholism ◦ Rh Null Phenotype

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Sickle Cells (Drepanocytes)

Have at least one pointed end.

Surface area of cell much greater than normal cell.

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Sickle Cells (Drepanocytes)

Low oxygen tension causes hemoglobin to polymerize, forming tubules that line up in bundles to deform cell.

Most sickle cells can revert back to normal shape when oxygenated.

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Sickle Cells (Drepanocytes) Associated with the following disorders: ◦Sickle Cell Anemia ◦Hemoglobin C Disease

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AcanthocytesNormal or

slightly smaller size

Possess 3-12 thorny projections of uneven length along periphery of cell membrane.

Projections are blunt 18

Acanthocytes

Specific mechanism of formation unknown. 

Contain increased cholesterol-to-phospholipid ratio.

Surface area increased

Susceptible to removal by spleen

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AcanthocytesPossible pathologies include:

◦ Alcohol Intoxication ◦ Pyruvate Kinase Deficiency ◦ Congenital Abetalipoproteinemia ◦ Vitamin E Deficiency ◦ Post-Splenectomy

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Fragmented CellsIncludes:

◦ Burr Cells◦ Helmet Cells◦ Schistocytes

Fragmentation is defined as a loss of a piece of cell membrane that may or may not contain hemoglobin.

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Fragmented Cells

Two pathways that lead to fragmentation:

◦ Alteration of normal fluid circulation (vasculitis, malignant hypertension, heart valve replacement).

◦ Intrinsic defects of red cell that make it less deformable (spherocytes and antibody-covered red cells).

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Prominent MorphologyFragmented Cells

Possible Pathology

Burr Cells

Renal diseas

e

Liver Diseas

eBurns

Schistocytes

Prosthetic

Heart Valve

Microangiopa

thic Hemol

ytic Anemi

a

DIC

TTP

HUS

Clostridial

Infections

Helmet Cells

G6PD Deficiency

Pulmonary Emboli

Burr Cells (Echinocytes)Red cells with

10-30 evenly spaced spicules over the surface of the cell. 

Normocytic and normochromic. 

In large numbers, are an artifact of sample contamination. 24

Burr Cells (Echinocytes)

"True" burr cells occur in small numbers in uremia, heart disease, stomach cancer, bleeding peptic ulcers, and in patients with untreated hypothyroidism. 

Seen in liver disease, renal disease, and burn patients. 

May occur in any situation that causes change in tonicity of intravascular fluid (dehydration). 25

Helmet Cells (Bite Cells) Usually have two

projections surrounding an empty area of red cell membrane. 

Looks as if cell has had a bite taken out of it. 

Caused by spleenic pitting and impalement of the RBC on fibrin strands

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Helmet Cells (Bite Cells)

In conditions where red cells have large inclusion bodies (such as Heinz bodies

G6PD deficiencyMay be seen in

patients with pulmonary emboli, and disseminated intravascular coagulation (DIC)

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SchistocytesExtreme cell fragmentationCell is missing

whole pieces of membrane.  

Causes bizarre shapes of red cells. 

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Schistocytes

Caused by loss of membrane by mechanical means

See in patients with microangiopathic hemolytic anemia, DIC, heart valve surgery, or severe burns.

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Teardrop CellsAppear as pear-

shaped cells.  Length of tail varies.  May be microcytic, normocytic, or macrocytic.

Exact formation process unknown.  Commonly seen in red cells that contain large inclusion bodies.

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Teardrop Cells

Most commonly seen in idiopathic myelofibrosis, thalassemia, and iron deficiency anemia.

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ReferencesHarmening, D. M. (2009). Clinical

Hematology and Fundamentals of Hemostasis. Philadelphia: F.A Davis.

McKenzie, S. B., & Williams, J. L. (2010). Clinical Laboratory Hematology . Upper Saddle River: Pearson Education, Inc.

http://www.ezhemeonc.com/index.php/hematological-disorders/

http://www.wiwe.net/irene/lab/chemheme/heme/microscope/stomatocyte.htm

http://home.ccr.cancer.gov/oncology/oncogenomics/WEBHemOncFiles/Review%20of%20Terms.html