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 or folate deficiency
    • Myelodysplastic syndrome
    • Medications: allopurinol, aminosalicylic acid (decreased folate), antacids (decreased B12), ampicillin and other penicillins (decreased folate), azathioprine, capecitabine, chloramphenicol (decreased folate), cladribine, cytosine arabinoside (ara-C), erythromycin (decreased folate), estrogens (decreased folate), fludarabine, fluorouracil, gadolinium, gemcitabine, histamine H2 blockers (decreased B12), hydroxyurea, imatinib, lamivudine, leflunomide, mercaptopurine, metformin (decreased folate), methotrexate, mycophenolate mofetil, nitrofurantoin (decreased folate), pentostatin, phenytoin (folate), primadone, proton pump inhibitors (decreased B12), sunitinib, teriflunomide, tetracyclines (decreased folate), thioguanine, trimethoprim, zidovudine
  • Reticulocytosis
    • Hemolytic anemia
    • Medications causing hemolytic anemia in G6PD deficiency: dapsone, methylene blue, nitrofurantoin, pegloticase, primaquine, rasburicase
    • Bone marrow recovery after chemotherapy or hematopoietic stem cell transplant
    • Increased erythropoiesis following administration of erythropoietin, repletion of iron, vitamin B12, or folate
    • Recovery from bleeding episode
  • Other
    • Alcohol
    • Liver disease
    • Hypothyroidism
    • HIV
    • Medications: triamterene, valproic acid

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