Clinical Hematology Quiz

Evaluation of Red Cell Morphology & Introduction to Platelets & White Cell Morphology

• Objectives:
  • Discuss hematology stains to prepare blood films
  • Identify normal red blood cell morphology on peripheral smears
  • Define anisocytosis and poikilocytosis, and list clinical conditions in which they might be observed
  • Define normochromic, hypochromic, microcytic, and macrocytic, and relate them to red cell indices
  • Correlate red blood cell indices with red blood cell morphology
  • Define red blood cell morphological abnormalities and the most common red blood cell inclusions
  • List conditions demonstrating leukocyte morphological abnormalities on peripheral blood smears
  • Describe normal and abnormal platelet morphology on peripheral blood smears

Peripheral Blood Smear

• Reasons:
  • Perceived clinical features
  • Abnormalities in Complete Blood Count (CBC)
• Advantages:
  • Detecting or verifying abnormalities
  • Providing information for differential diagnosis

Peripheral Blood Smear (continued)

• Components:
  • Red cells: size, shape, distribution, hemoglobin concentration, color, presence of inclusions
  • Platelets: count, shape, size, clumping
  • White cells: differentials, assessing nuclear and cytoplasmic abnormalities, abnormal inclusions

Hematology Stain

• Nonvital (dead cell) polychrome stain (Romanowsky):
  • Wright's stain is the most common
  • Contains methylene blue (basic, stains acidic components like DNA and RNA blue) and eosin (acidic, stains basic components like hemoglobin red-orange)
  • Methanol fixative fixes cells to the slide
• Staining process details:
  • Staining begins after a phosphate buffer (pH between 6.4 and 6.8) is added
  • Causes of RBCs too red and WBC nuclei poorly stained:
    • Buffer or stain below pH 6.4
    • Excess buffer
    • Decreased staining time
    • Increased washing time
    • Thin smear
    • Expired stains
  • Causes of RBCs and WBC nuclei too blue:
    • Buffer or stain above pH 6.8
    • Too little buffer
    • Increased staining time
    • Poor washing
    • Thick smear
    • Increased protein
    • Heparinized blood sample

Nonvital Monochrome Stain

• Prussian blue (Perl's test) is an example, staining specific cellular components, such as iron granules in red blood cells (siderotic iron granules).

Supravital (living cell) Monochrome Stain

• Used to stain specific cellular components without fixing
• Examples include new methylene blue, which precipitates RNA in reticulocytes, and neutral red with brilliant cresyl green, used for visualizing Heinz bodies.

Examination of Blood Smear

• Low power scan (10x):
  • Check staining quality
  • Determine blood cell distribution
  • Detect any clumps or abnormal cells
  • Identify optimal area for examination and enumeration
• High power scan (40x):
  • Determine white blood cell (WBC) estimate
  • Count WBCs in 10 fields and average
  • Correlate WBC estimate with total WBC count per cubic millimetre
  • Evaluate morphology and record abnormalities
• Oil immersion examination (100x):
  • Perform 100 WBC differential counts.
  • Check red blood cells for anisocytosis, poikilocytosis, hypochromia, polychromasia, and inclusions
  • Estimate platelets/µL and evaluate their morphology.
  • Correct total WBC count if >10 nucleated red blood cells per 100 WBCs

Examination of Blood Smear (Assessment Question)

• A sample assessment question is provided, including data on a patient's white blood cells, red blood cells, hemoglobin, and platelets, and asking for the corrected white blood cell count.

Normal Red Cell

• Dimensions: 6-8 μm x 1.5-2 μm
• Volume: 80-100 fL; normal variation is about 5%
• Central pallor: 2-3 μm
• Appearance on Wright-stained film: reddish-orange, biconcave disc shape

Assessment of Red Cell Abnormality

• Assessing abnormal morphology involves evaluating (size anisocytosis, shape- poikilocytosis, and evaluation of the red blood cell indices (and RDW), accounting for the percentage of cells differing with regards to size or shape from the normal red blood cells in 10 fields). A grading scale is provided to determine if the deviations are slight, moderate, or marked.

Variations in Red Cell Distribution

• Normal distribution: Cells are dispersed
• Agglutination: Red blood cells clustered together (often due to cold agglutinins), saline solution may not break this clumping; warming at 37°C may help, and MCHC is often falsely elevated.
• Rouleaux: Red blood cells stacked like coins (due to increased plasma proteins, like in multiple myeloma).

Variations in Size-Anisocytosis: Macrocytes

• Size ≥ 9 μm
• MCV > 100 fL
• Mechanisms of macrocyte formation include DNA synthesis impairment, accelerated erythropoiesis, or increased membrane cholesterol & lecithin

Variations in Size-Anisocytosis: Microcytes

• Size < 7 μm
• MCV < 80 fL
• Mechanisms of microcyte formation include impaired hemoglobin synthesis (ineffective iron utilization, reduced absorption, genetic defects in globin synthesis)

Variations in Shape: Ovalocytes and Elliptocytes

• Ovalocytes are egg-shaped.
• Elliptocytes are pencil-shaped.

Variations in Shape: Stomatocytes

• Stomatocyte has a characteristic "mouth" or slit-like central pallor.

Variations in Shape: Acanthocytes

• Acanthocytes have irregular, thorny projections (spurs).

Variations in Shape: Spherocytes

• Spherocytes are small, round cells with reduced central pallor.

Variations in Shape: Tear Drop Cells

• Tear cells are pear-shaped and often associated with conditions causing increased cellular damage or abnormal inclusions.

Red Blood Cell Inclusions

• Howell-Jolly Bodies: nuclear remnants, visible as small, dark-staining dots
• Basophilic Stippling: clusters of ribosomes, visible as fine-to-coarse, dark-staining dots
• Siderotic Granules (Pappenheimer Bodies): iron deposits, visible as small, dark-staining granules
• Heinz Bodies: denatured hemoglobin, visible with supravital stains.
• Cabot Rings: mitotic spindle remnants, visible as ring-like or figure-8 structures
• Hb H (Golf Ball): denatured hemoglobin in α-thalassemia major, observed as golf-ball shaped inclusions with supravital stains.
• Hb SC (Fingerlike Projection): hemoglobin SC crystals (Washington Monument) observed in hemoglobin SC disease.
• Malarial Parasites: specific shapes and locations of protozoan parasites associated with malaria in different stages.

Examination of Platelet Morphology

• Platelets:
  • Discoid shape, 2-4 micrometers in diameter.
  • A small number of large platelets (up to 5 µm) can be seen in normal films.
  • Mean platelet volume (MPV): 6.8-10.2 fL (analogous to the mean corpuscular volume for red blood cells)
  • Normal platelet (granule) size and distribution are described, as well as changes potentially observed after splenectomy.
• Very high platelet counts:
• Associated with myeloproliferative disorders (MPDs)
• Can be seen with inflammatory or bleeding disorders.
• Abnormalities in platelet morphology could be due to underlying diseases such as hyposplenism and coeliac disease, and various other conditions such as Bernard-Soulier syndrome, Grey platelet syndrome, and platelet-satellitosis.
• Platelet aggregation
• Dwarf megakaryocytes

Leucocytes (Normal & Abnormal Morphology)

• Segmented neutrophils (PMNs):
• Description of normal morphology, including nucleus and cytoplasm
• Eosinophils: Description of normal morphology, noting specific granules, and indicating the relative frequency in blood
• Basophils: Description of the normal morphology of basophils, including their primary (basic) and secondary (specific) granules.
• Monocytes: Description of normal morphology.
• Lymphocytes: Description of normal morphology.
• Reactive lymphocytes: Characteristics indicative of activation, like increased cytoplasm and irregular nuclei.
• Toxic Granulation: Dark-blue-black cytoplasmic granules in neutrophils.
• Dohle bodies: Small light-blue staining areas in the cytoplasm.
• Hypersegmented neutrophils: Neutrophils have 5 or more nuclear lobes.
• Pelger-Huet Anomaly: neutrophils with 2 nuclear lobes.
• Chediak-Higashi Syndrome: neutrophils with abnormal, large granules.
• Alder-Reilly Anomaly: neutrophils with granules that stain darkly.
• May-Hegglin Anomaly: neutrophils with Dohle-like bodies and abnormal giant platelets.
• Auer Rods: Rod-like inclusions found in myeloblasts (acute myeloid leukemia).
• Vacuolated Neutrophils: Round, clear areas within the cytoplasm that are a result of active phagocytosis.
• Smudge (Basket) Cells: Degenerating leukocytes with condensed nuclear chromatin.
• Hypogranular (Agranular) Neutrophils: Neutrophils with fewer granules. These can occur in myelodysplastic syndrome (MDS) or myeloid leukemias.
• LE Cells: Neutrophils that have engulfed other cells' nuclei (seen in systemic lupus erythematosus).
• Barr Bodies (Drum-Stick): Small, well-defined chromosomal structures in female neutrophils.
• Erythrophagocytosis: Neutrophils or monocytes that have ingested red blood cells.
• Leukoagglutination: Clusters of leukocytes.
• Effect of Storage on Blood Cell Morphology: Describes the changes in morphology after blood samples are stored for intervals, that may make interpretation easier to perform

Test your knowledge on Clinical Hematology and learn about key concepts related to hematology and hemostasis. This quiz covers various topics, including cell morphology, specific conditions, and important details from 'Clinical Hematology & Fundamentals of Hemostasis'.