Peripheral blood film

Erythrocytes

Distribution

• Agglutination: suggests IgM, either expected response to infection or autoimmune hemolytic anemia
• Rouleaux: paraproteinemia

Morphology

• Anisocytosis: size
• Poikilocytosis: shape
• Spherocytosis: Hereditary Spherocytosis (HS) or autoimmune hemolytic anemia
• Acanthocytes: irregular cellular projections seen in hyposplenism
• Echinocytes (burr cells): regular cellular projections that is usually artefact
• Bite cells: oxidative stress, like G6PD deficiency

Size

• Microcytic red blood cells
  • Iron-deficiency anemia
    • Anisopoikilocytosis
    • Target cells
    • Increased RDW
    • Increased platelets
  • Thalassemia
    • Basophilic stippling
    • Increased RBC count to greater than 3x Hgb
    • Increased reticulocytes
    • Positive HbH test (in alpha-thal) or Hb electrophoresis (in beta-thal)
• Macrocytic red blood cells
  • Megaloblastic with hypersegmented neutrophils
    • Vitamin B12 deficiency, folate deficiency, medications, and myelodysplastic syndrome
  • Non-megaloblastic
    • Alcohol, liver disease, hypothyroidism

Leukocytes

• CLL
  • Smudge cells
  • Soccer ball cells
• Reactive changes
  • Dohle bodies: diffuse blue dot in cytoplasm
  • Hypergranulation
  • Vacuolation
• Left shift: increase in
  • Promyelocytes
  • Myelocytes
  • Metamyelocytes
  • Bands
  • Neutrophils