normal and abnormal barrett w. dick, m.d. director, hematology laboratories memorial medical center...

ERYTHROPOIESISNormal and abnormal

Barrett W. Dick, M.D.Director, Hematology LaboratoriesMemorial Medical CenterSpringfield. IL Clinical Professor, Pathology and MedicineSouthern Illinois School of Medicine

RBC development

Increasing cytoplasmic hemoglobin

Decreasing cytoplasmic RNA

POLYCHROMATOPHILIA VS. NORMAL

Immature red cells are bigger, bluer and have less central pallor than mature rbc.

NOTE: On the left is a diagrammatic representation of a young red cell, usually described as “polychromatophilic”. Note that it is larger and bluer than a mature red cell on the right. This is due to its RNA content.

Reticulocytes vs. Polychromasia

Reticulocytes vs. Polychromasia

Reticulocytes require special techniques for measurement

The two terms are not equivalent but frequently, but incorrectly, used as equivalent

Estimating polychromasia from a stained blood smear is not a substitute for performing a reticulocyte count. The correlation is poor.

Increased Polychromasia

Polychromatophilic Rbc

Blood Smear Examination

Too thick Too thin

Area behind “feather edge”-

Just right.

Smear ExaminationFeather EdgeThin Area

Low Power Examination Of Blood Smear

Performed at 10X magnification Evaluate quality of smear- appropriate thin area Check for increased rouleaux formation Scan for white cell distribution- even With practice can estimate the white count and

differential: at very least make sure they correlate with machine count and/or manual diff

Thin Area of Smear

10X mag

Ideal Area of Blood Smear

Red cells close, evenly spaced without significant overlapping

50X Oil

Increased Rouleaux Formation

Some degree of rouleaux formation is normal; this is increased

High Power Examination

Scan performed at no lower than 40X coverslipped smear or 50X oil Estimate the differential and look for

qualitative Wbc abnormalities Rbc morphology Platelet estimate

Perform a differential at 100X if specimen has been flagged as being abnormal- 200 cells.

Normal Rbc

Rbc variation

Anisocytosis- Variation in size Poikilocytosis- Variation in shape

Slight variation of size and shape is normal. When abnormalities are reported, what it should mean is that more than normal variation is present.

Normal Size Distribution

50 100 200RBC

NOTE: This illustrates a normal red cell distribution with the horizontal scale representing cubic micra. The RDW is by convention a mathematical expression of the width of the curve near the base.

Red Cell Size

Red cell size can only be measured accurately using electronic instrumentation to measure the volume (MCV).

On blood smear examination, the size estimate is based on diameter, which is not very accurate and does not correlate well with the MCV

Small lymphocyte nuclei are a rough guide to normal Rbc diameter

Microcytic Rbc

7.5 mu

Avr.diameter of normal Rbc= 7.5 mu

Microcytic, Hypochromic Rbc

Microcytic Hypochromic Rbc

Hypochromia is the most frequently overcalled abnormality on blood smears, usually due to technical factors

When real, usually due to advanced iron deficiency Men: Hgb<10g/dl Women: Hgb<8g/dl

Rarely in our population- thalassemia major

Macrocytic Rbc

This smear also illustrates increased variation in size (anisocytosis) and increased variation in shape (poikilocytosis).

Abnormal red cell shapes- poikilocytosis

Elliptocytes (ovalocytes)

Elliptocytes are a common non-specific abnormality. Hereditary elliptocytosis is also relatively common and is usually not hemolytic. The hereditary form is more common in peoples of African origin

Burr Cells, Acanthocytes, Crenated Cells

Terms that are frequently, but incorrectly, used interchangeably. When strictly defined the terms can have specific clinical correlations.

Acanthocyte

Burr Cell Crenated Rbc

Burr Cells

Burr cells have rounded, blunt projections at the edges and have central pallor

Burr Cells

Uremia Liver disease Metabolic

imbalance

Acanthocytes

Acanthocytes look like spherocytes with irregularly spaced, thin, spiny projections

Acanthocyte

Differential Dx for Acanthocytes

Liver Disease Post-Splenectomy aBeta

lipoproteinemia

Crenated Red Cells

Crenated red cells have the appearance of sea urchin eggs: short, evenly-spaced, broad-based spikes projecting in three dimensions. They are seen in some severely ill patients with marked electrolyte abnormalities. In a reference laboratory setting, they are a frequent manifestation of a poorly preserved specimen..

Post-Splenectomy

Howell-Jolly Bodies Acanthocytes Target Cells Lymphocytosis

Post-Splenectomy

Howell-Jolly Body

Target Cells

Target Cells

Liver disease and/or hyperbilirubinemia

Post-splenectomy Hemoglobinopathies

Hemoglobin C syndromes:▪ AC, SC, C-thal▪ NOT thalassemia minor, <1% of cases

Spherocytes

The cells are small in diameter but not in volume. Because of their spherical shape they do not flatten on the slide.

Differential Dx- Spherocytes

Hereditary Spherocytosis Autoimmune hemolysis Alloimmune hemolysis-

Newborns with ABO incompatibility Delayed transfusion reactions

Thermal injury- burn patients Occasionally- non-specific with

transfused red cells

Osmotic Fragility Test

Microspherocytes secondary to severe thermal injury

Tear Drop Cells

Common in disorders associated with marrow infiltration and splenomegaly

Coarse Basophilic Stippling

Coarse stippling is usually associated with some form of dyserythropoeisis.

Schistocytes- Rbc fragments, so-called “Microangiopathic Hemolytic Anemias”

TTP /HUS Vasculitis Partially thrombosed vessels including

heart chambers Sever cardiac valve abnormalities or

malfunctioning prosthesis DIC- rarely; most often associated with

chronic DIC

Schistocytes

Schistocytes- Rbc fragments

Pocked (Pitted”) Red Cells

These cells look like spherocytes with bites in the edges, aka, “bite” cells. This is due to removal of denatured hemoglobin by the pitting function of the spleen

Heinz Body Hemolytic Anemias

Heinz Bodies are denatured hemoglobin usually due an oxidant. They are removed by the spleen causing deformed rbc- “pitted” rbc, aka “pocked” or “bite” cells

Hereditary G6PD deficiency: hemolysis is usually drug

induced or can be induced non-specifically by stress, such as infection

Unstable hemoglobins Acquired: oxidant drug-induced without a hgb

or enyzmatic abnormality

Common Hemoglobinopathies with Peripheral Blood Abnormalities

Thalassemia minor- microcytosis with mild or no anemia; worldwide in distribution

Hemoglobin AC- Target cells, sometimes spherocytes (few); from West Africa

Hemoglobin AE or EE- Microcytosis and target cells with minimal or no anemia: from SE Asia

Hemoglobin SS- Sickle cells with variable anemia

Hemoglobin SC- Target cells, spherocytes, sometimes sickle cells depending on the severity; may be asymptomatic

Thalassemia minor

Mild or no anemia with microcytosis. The prevalence of target cells in this disorder is markedly overstated in texts and in the literature

Sickle Cell Anemia

S-C Disease

SC crystals have a characteristic appearance with blunted, rhomboidal ends

Screening for Hemoglobinopathies

Thal minor CANNOT be diagnosed by Hgb electrophoresis in the overwhelming majority of patients; it is a diagnosis of exclusion: R/O iron deficiency

Hemoglobin electrophoresis is the procedure of choice for testing for other hemoglobin abnormalities; quick tests are not recommended

Screening for Hemoglobinopathies

A F S A2 D C G E

Malaria

Malaria

Malaria

Platelet overlying a red cell

These are frequently mistaken for malaria parasites