Abnormal Hematology: RBC Morphology, Indices, and Inclusions

Cold agglutinins

Your own antibody attacking your RBC.

Normocytic

Normal size of RBC 80-100 femtoliters.

Microcytic

RBC smaller than 80 femtoliters.

Macrocytic

RBC that are bigger than 100 femtoliters.

Dimorphic population

2 different groups of RBC, small and big RBC together.

Hypochromic

Central pallor is bigger than 3um.

Polychromasia

Cells appear grey-blue in color due to residual RNA making it a premature RBC.

Agglutination

Irregular grape like cluster of red blood cells caused by cold agglutinins.

Rouleaux

RBC are aligned on top of each other resembling a stack of coins.

Anisocytosis

The variation of RBC shape.

Acanthocytes

Also called a spur cell; RBC with 3-12 spicules of varying lengths irregularly disturbed across the surface.

Burr cells

Also called an echinocyte; RBC with approx 10-30 rounded spicules evenly placed over the surface.

Elliptocytes

Cigar shaped with hemoglobin on both ends of the cell.

Helmet cells

Also called schistocytes; RBC fragment that looks like a half moon with two distinct projections.

Teardrop cells

Also called dacrocytes; looks like a teardrop and found after spleen pits out inclusions.

Ovalocytes

More egg shaped with greater tendency to vary in hemoglobin content.

Schistocytes

RBC fragment resulting from trauma to the RBC membrane.

Sickle cells

Also called drepanocytes; RBC that are crescent or sickle shaped with pointed projections.

Spherocytes

RBC lack central pallor due to abnormal cell membrane, more fragile and cannot take in water.

Stomatocytes

Has a cut silt like through the RBC due to membrane defect, increased permeability to sodium.

Target cells

Also called codocytes; thin bell shaped cells with increased surface to volume ratio.

CBC results in agglutination

Causes falsely elevated MCV, MCH, and MCHC; falsely decreased RBC count.

Characteristic parameter for spherocytes

MCHC greater than 36 g/dL.

Spherocyte ability to take in water

More fragile and cannot take in water otherwise it will burst.

Stomatocyte ability to take in water

Increased permeability to sodium letting water enter the cell.

Target cell

Called a codocyte cell

Target cell morphology

Thin bell shaped cells with increased surface to volume ratio

Appearance of target cells

Resemble a target with a bullseye in the center

Fragility of target cells

Less fragile than normal RBC and is able to take in water

Conditions associated with target cells

Seen most commonly in liver diseases, renal disease, and hemoglobinopathies

Associated conditions of target cells

Associated with hereditary stomatocytosis, alcoholic cirrhosis, and lead intoxication

Howell-Jolly bodies

Small, round DNA remnants at cell periphery

Basophilic stippling

Multiple fine or coarse blue granules composed of aggregated RNA

Pappenheimer bodies

Iron granules (non-heme) in clusters at cell edge

Heinz bodies

Denatured/oxidized hemoglobin

Cabot rings

Mitotic spindle remnants (microtubules)

Reticulocytes

Early RBC with residual RNA

HbC crystals

Dense, rectangular crystals with a bar of gold appearance

HbSC crystals

Finger-like, blunt-ended projections

Plasmodium (Malaria)

Signet ring appearance seen in malaria

Babesia

Has maltese cross appearance in blood circulation

MCV (Mean Corpuscular Volume)

80-100 fL = normocytic, >100 fL = macrocytic, <80 fL = microcytic

MCH (Mean Corpuscular Hemoglobin)

Formula: MCH = HGB × 10 ÷ RBC

MCHC (Mean Corpuscular Hemoglobin Concentration)

Formula: MCHC = HGB × 100 ÷ HCT

Color (Chromasia)

Normochromic — normal hemoglobin content, Hypochromic — enlarged central pallor

RBC Clumping

Agglutination — RBC clumping; can resolve with warming

Ovalocytes / Elliptocytes

Ovalocytes: oval RBCs, Elliptocytes: cigar-shaped RBCs

Sickle Cells (Drepanocytes)

Crescent-shaped with pointed ends

Keratocytes (Helmet/Bite Cells)

Half-moon shape with two projections

Echinocytes (Burr Cells)

10-30 evenly spaced, rounded spicules

Acanthocytes (Spur Cells)

3-12 irregular, unevenly spaced spicules

Dacrocytes (Teardrop Cells)

Teardrop-shaped; tips should point in the same direction

Codocytes (Target Cells)

Thin, bell-shaped cells with increased surface-to-volume ratio

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