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11 Variations in shape and distribution of erythrocytes

Poikilocytosis is a general term for the presence of abnormally shaped red blood cells. In most cases, we have opted to use the more specific name for each abnormally shaped red blood cell in place of the term poikilocytosis.

Acanthocyte

Spur cell

FIGURE 11–1A Acanthocytes.

FIGURE 11–1B Acanthocytes.

FIGURE 11–1C Acanthocytes; two nucleated red blood cells in field.

Description:

Erythrocyte with irregularly spaced projections that vary in width, length, and number; usually dense, lacking central pallor

Associated with:

Severe liver disease, splenectomy, malabsorption, hypothyroidism, vitamin E deficiency, abetalipoproteinemia

Schistocyte

Schizocyte

FIGURE 11–2A Schistocytes.

FIGURE 11–2B Schistocytes.

FIGURE 11–2C Bite cells.

FIGURE 11–2D Blister cells.

Color:

Red to salmon

Shape:

Fragmented erythrocytes; many sizes and shapes may be present on a smear; often display pointed extremities

Associated with:

Microangiopathic hemolytic anemia (hemolytic uremic syndrome, thrombotic thrombocytopenic purpura, disseminated intravascular coagulation), severe burns, renal graft rejection

Note:

Bite and blister cells are the result of splenic pitting of Heinz bodies (see Figure 12-5, B). These cells are often included in the schistocyte category.

Echinocyte

Burr cell

FIGURE 11–3A Echinocytes/burr cells.

FIGURE 11–3B Echinocytes/burr cells.

Description:

Erythrocyte with short, evenly spaced projections usually with central pallor

Associated with:

Uremia, pyruvate kinase deficiency, microangiopathic hemolytic anemia, neonates (especially premature), artifact

Spherocyte

FIGURE 11–4A Spherocytes.

FIGURE 11–4B Spherocytes.

Color:

Darker than surrounding red blood cells

Shape:

Round; no central pallor zone

Associated with:

Hereditary spherocytosis, some hemolytic anemias, transfused cells, severe burns

Target cell

Codocyte

FIGURE 11–5A Target cells.

FIGURE 11–5B Target cells.

Color:

Red to salmon

Shape:

Bull’s eye; central concentration of hemoglobin surrounded by colorless area with peripheral ring of hemoglobin resembling bull’s eye; may be bell (Figure 11-5, A, arrow A) or cup (see Figure 11-5, A, arrow B) shaped.

Associated with:

Hemoglobinopathies, thalassemia, iron deficiency anemia, splenectomy, obstructive liver disease

Sickle cell

Drepanocyte

FIGURE 11–6A Sickle cells.

FIGURE 11–6B Sickle cells.

FIGURE 11–6C Schistocyte resembling sickle cell. (Note: Central area is markedly thicker than the ends.)

Color:

Dark red to salmon, lacks central pallor

Shape:

Elongated cell with point on each end; may be curved or S-shaped

Composition:

Hemoglobin S

Associated with:

Homozygous hemoglobin S disease, sometimes hemoglobin SC

Hemoglobin C crystal

FIGURE 11–7A Hemoglobin CC crystals.

FIGURE 11–7B Hemoglobin CC crystals with visible red blood cell membrane.

Color:

Dark red

Shape:

Hexagonal

Number per cell:

1

Composition:

Hemoglobin C

Associated with:

Homozygous hemoglobin C disease

Hemoglobin SC crystal

FIGURE 11–8A Hemoglobin SC.

FIGURE 11–8B Hemoglobin SC.

FIGURE 11–8C Hemoglobin SC.

Color:

Dark red

Shape:

1-2 fingerlike projections; may look like a mitten or the Washington Monument (obelisk); cell may appear folded

Number per cell:

1-2

Composition:

Hemoglobin SC

Associated with:

Hemoglobin SC disease

Elliptocyte/ovalocyte

FIGURE 11–9A Elliptocytes.

FIGURE 11–9B Ovalocytes.

Description:

Elliptocyte—cigar-shaped erythrocyte

Description:

Ovalocyte—egg-shaped erythrocyte

Associated with:

Hereditary elliptocytosis or ovalocytosis, thalassemia major, iron deficiency anemia, megaloblastic anemias (macro-ovalocytes), myelophthisic anemias

Tear drop cell

Dacryocyte

FIGURE 11–10A Tear drop cells.

FIGURE 11–10B Tear drop cells.

Description:

Erythrocyte shaped like a tear drop or pear; may have one blunt projection

Associated with:

Primary myelofibrosis, thalassemia, myelophthisic anemia, other causes of extramedullary hematopoiesis

Stomatocyte

FIGURE 11–11A Stomatocytes.

FIGURE 11–11B Stomatocytes.

Description:

Erythrocyte with slitlike area of central pallor (similar to a mouth or stoma)

Associated with:

Hereditary stomatocytosis, alcoholism, liver disease, Rh null phenotype, artifact

Rouleaux versus autoagglutination

Rouleaux

FIGURE 11–12A Rouleaux (×500).

FIGURE 11–12B Rouleaux (×1000).

Description:

Erythrocytes arranged in rows like stacks of coins; increased proteins in patients with rouleaux may make the background of the slide appear blue

Associated with:

Acute and chronic inflammatory disorders, plasma cell myeloma, lymphoplasmacytic lymphoma

Note:

These aggregates will disperse with saline.

Autoagglutination

FIGURE 11–12C Autoagglutination (×500).

FIGURE 11–12D Autoagglutination (×1000).

Description:

Clumping of erythrocytes; outlines of individual cells may not be evident

Associated with:

Antigen-antibody reactions

Note:

Aggregate will not disperse with saline.

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11 Variations in shape and distribution of erythrocytes

Poikilocytosis is a general term for the presence of abnormally shaped red blood cells. In most cases, we have opted to use the more specific name for each abnormally shaped red blood cell in place of the term poikilocytosis.

Acanthocyte

Spur cell

FIGURE 11–1A Acanthocytes.

FIGURE 11–1B Acanthocytes.

FIGURE 11–1C Acanthocytes; two nucleated red blood cells in field.

Description:

Erythrocyte with irregularly spaced projections that vary in width, length, and number; usually dense, lacking central pallor

Associated with:

Severe liver disease, splenectomy, malabsorption, hypothyroidism, vitamin E deficiency, abetalipoproteinemia

Schistocyte

Schizocyte

FIGURE 11–2A Schistocytes.

FIGURE 11–2B Schistocytes.

FIGURE 11–2C Bite cells.

FIGURE 11–2D Blister cells.

Color:

Red to salmon

Shape:

Fragmented erythrocytes; many sizes and shapes may be present on a smear; often display pointed extremities

Associated with:

Microangiopathic hemolytic anemia (hemolytic uremic syndrome, thrombotic thrombocytopenic purpura, disseminated intravascular coagulation), severe burns, renal graft rejection

Note:

Bite and blister cells are the result of splenic pitting of Heinz bodies (see Figure 12-5, B). These cells are often included in the schistocyte category.

Echinocyte

Burr cell

FIGURE 11–3A Echinocytes/burr cells.

FIGURE 11–3B Echinocytes/burr cells.

Description:

Erythrocyte with short, evenly spaced projections usually with central pallor

Associated with:

Uremia, pyruvate kinase deficiency, microangiopathic hemolytic anemia, neonates (especially premature), artifact

Spherocyte

FIGURE 11–4A Spherocytes.

FIGURE 11–4B Spherocytes.

Color:

Darker than surrounding red blood cells

Shape:

Round; no central pallor zone

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