Red Cell Morphology

Basic Introduction

Reference: Color Atlas of Hematology by Eric Glassy, M.D.

RBC Classification- - - - - - SIZE - - - - - - • Normocyte• Microcyte• Macrocyte• Anisocytosis

- - - - - - SHAPE - - - - - - • Acanthocytes• Burr Cells• Ovalocytes• Tear Drops• Stomatocytes• Spherocytes• Schistocytes• Target Cells• Sickle Cells

- - - - - - PALLOR - - - - - - • Normochromic• Hypochromic• Hyperchromic• Polychromasia

- - - - INCLUSIONS - - - - • NRBC’s• Howell-Jolly bodies• Basophilic Stippling• Pappenheimer bodies• Hemoglobin crystals

RBC Parameters

• MCV = X 10 80 – 100 fL

• MCH = X 10 27 – 31 pg/cell

• MCHC = X 100 32 – 36 g/dL

Hct_ RBC

Hgb_ RBC

Hgb_ Hct

Microcytic < 80 fL Macrocytic > 100 fL

Hypochromic < 32 g/dL Hyperchromic > 36 g/dL

Normal RBC

Normal RBC50x Objective

Normal RBC100x Objective

Microcytes

• SYNONYMS: microcytic RBCs

• KEY FEATURES:

– Size: MCV < 80 fL; diameter < 6 m

– Cytoplasm: normochromic or often hypochromic with increased central pallor

MicrocyticCompare RBC and Lymph sizes

Macrocytes

• SYNONYMS: macrocytic RBCs; macro-ovalocyte (oval form)

• KEY FEATURES:

– Size: MCV > 100 fL; diameter > 8 m

– Shape: round or oval

– Cytoplasm: normochromic, but may sometimes be hypochromic; no polychromasia

MacrocytesCompare RBC and Lymph sizes

AnisocytosisSize Variation

RDW Guide (g/dL)• Slight = 16-20• Moderate = 20-26• Marked = > 26

• Only use RDW as a guide

Hypochromia

• SYNONYMS: hypochromic RBCs

• KEY FEATURES:

– Size: microcytic or macrocytic cells

– Cytoplasm: central pallor > 1/3 of RBC diameter (increased central pallor); some cells contain so little hemoglobin that they are “ghost cells”

Microcytic – HypochromicCompare RBC and Lymph sizes

Polychromasia

• SYNONYMS: polychromatophil; reticulocyte (presumptive)

• KEY FEATURES:

– size: slightly larger than erythrocyte

– shape: round to slightly oval

– cytoplasm: little or no central pallor; color is slightly more gray-blue or purple than that of an erythrocyte

Polychromic

Acanthocytes

• SYNONYMS: spur, spike or horn cell

• APPEARANCE: Crenated RBC with very spiny, irregular projections

• KEY FEATURES:

– Size: diameter smaller than normal cells (like spherocytes)

– Shape: 3 – 20 irregular membrane spikes, unevenly distributed

– Cytoplasm: no central pallor

Acanthocytes

Burr Cells

• SYNONYMS: Echinocyte , crenated cell

• APPEARANCE: Similar to crenated RBCs but projections are less pointed and more regular than acanthocytes

• KEY FEATURES:

– Size: normocytic

– Shape: 10-30 evenly distributed short, blunt or pointed spicules; projections uniformly sized

– Cytoplasm: normochromic; retains central pallor (unlike acanthocytes)

Burr Cells

Elliptocytes

• SYNONYMS: ovalocyte, pencil cell

• APPEARANCE: elongate with round ends (cigar, egg, pencil shapes)

• KEY FEATURES:

– Size: variable; usually longer than normal red cell and much more narrow

– Shape: uniform, symmetrical rod shape; sides nearly parallel

– Cytoplasm: often retain central pallor

Elliptocytes

Teardrop Cells

• SYNONYMS: dacrycocyte

• APPEARANCE: Round cells with elongated tail or point; resembles a teardrop

• KEY FEATURES:

– Size: microcytic to normocytic

– Shape: teardrop or pear-shaped RBC with single tapered end (tail) that is blunt or round

– Cytoplasm: normochromic to hypochromic

Teardrop Cells

Stomatocytes

• SYNONYMS: hydrocyte

• APPEARANCE: RBC with a slit-like central pallor

• KEY FEATURES:

– Size: normocytic

– Shape: round; uniconcave disc

– Cytoplasm: normochromic; central pallor appears slit-like, straight, fish mouth, or curved rod-shaped; a few cells may have tri-polar pallor creating cells that resemble sleigh bells

Stomatocytes

Spherocytes

• SYNONYMS: none

• APPEARANCE: Cells appear perfectly round and have no central pallor; often smaller than normal RBCs

• KEY FEATURES:

– Size: slightly microcytic

– Shape: round to spherical

– Cytoplasm: no central pallor

Spherocytes50x Objective

Spherocyte100x Objective

Schistocytes

• SYNONYMS: helmet cell, triangulocyte, keratocyte, horn cell, fragmented RBCs

• APPEARANCE: Pieces of RBCs that can have a vast variety of shapes and sizes

• KEY FEATURES:

– Size: irregular cell sizes; usually microcytic

– Shape: shapes vary from helmet to triangular to unclassified fragments

– Cytoplasm: small fragments lack central pallor; horn cells can be normochromic

SchistocytesFragmented RBCs

Target Cells

• SYNONYMS: codocyte

• APPEARANCE: RBCs have a bullseye appearance

• KEY FEATURES:

– Size: normocytic to slightly macrocytic

– Shape: round

– Cytoplasm: increased surface membrane to volume ratio results in a central, darker hemoglobin region within the area of central pallor creating the appearance of a target or bullseye

Target Cells

Sickle Cells

• SYNONYMS: drepanocyte

• APPEARANCE: Usually a thin, crescent shaped cell

• KEY FEATURES:

– Shape: sickle shaped with at least one pointed end; may also be crescent-shaped, boat-shaped, filament shaped, holly-leaf form (rarely) and envelope shaped

– Cytoplasm: no central pallor; very dense hemoglobin concentration (normochromic to hyperchromic)

Sickle Cells50x Objective

Sickle Cells100x Objective

RBC Inclusions

• NRBCs

• Howell-Jolly Bodies

• Basophilic Stippling

• Pappenheimer Bodies

• Hemoglobin Crystals

Nucleated Red Blood Cells

• SYNONYMS: NRBCs

• APPEARANCE: RBC with a small, pyknotic nucleus with dense chromatin

• KEY FEATURES:

– Size: 8-10 m size; slightly larger than a mature RBC

– Cytoplasm: varies depending on stage of maturation; usually more blue-gray

NRBCsNucleated RBC

NRBCs

Howell-Jolly Bodies

• SYNONYMS: nuclear fragment, HJ bodies, Ho-Jo’s

• APPEARANCE: Large, singular dark purple inclusion

• KEY FEATURES:

– Size: 1 m; sometimes as small as 0.5 m

– Shape: spherical or oblong blue-purple or blue-black inclusion

– Cytoplasm: normochromic or hypochromic

– Location: eccentrically located (off center); usually a single inclusion, but multiple can be present

Howell-Jolly Bodies

Howell-Jolly Bodies

PappenheimerBodies (Iron)

Basophilic Stippling

• SYNONYMS: punctuated basophilia

• APPEARANCE: Medium-sized, blue-black dots (granules) evenly distributed throughout the RBC

• KEY FEATURES:

– Size of granules: numerous small coarse or fine granules; uniform in size and shape ; 0.5 m in diameter

– Cytoplasm: uniformly filled with deep blue or blue-gray dots

Basophilic Stippling

Pappenheimer Bodies

• SYNONYMS: none

• APPEARANCE: Small dark blue-purple staining hemoglobin iron granules; seen on Wright stained smear and confirmed with iron (Prussian blue) stain

• KEY FEATURES:

– Size: usually less than 1 m (sometimes <0.5 m)

– Shape: blue-purple granules with irregular, sharp edges (not round)

– Location: usually found along the periphery of the cell; one or two irregular, small blue-purple-green granules; if present in multiples, they form irregular closely aggregated clusters

Pappenheimer BodiesWright Stain

Pappenheimer BodiesIron Stain

Hemoglobin Crystals

• SYNONYMS: none

• APPEARANCE: dense staining, angular crystalline forms that vary in shape; may be rectangular, rod-shaped, tetragonal, octahedral (Washington monument, gold bar), spherocytic, rhomboid, or hexagonal

• KEY FEATURES:

– Size: variable since crystals may markedly distort the cell

– Shape: a normal disc shape is distorted by the crystal; cytoplasm contains the crystal, which is a precipitate of hemoglobin C or SC

– Cytoplasm: often pale or colorless; there is generally a clear area around the crystal

Hemoglobin SC Crystalsglove cells

Typical RBC Abnormal MorphologyPolychromasia Acanthocyte

Teardrop

Schistocyte

MicrocyteSpherocyte

Burr Cell

Elliptocyte

Target Cell

Hypochromic

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