Peripheral Blood Smear (PBS) Interpretation Guide

Comparison Table for Peripheral Blood Smear Findings in Various Diseases

Explanation of Findings

RBC Findings

• Spherocytes: Small, dense RBCs without central pallor; seen in hereditary spherocytosis and ABO incompatibility.
• Polychromasia: Bluish-tinted cells indicating increased reticulocytes; seen in conditions with increased RBC production.
• Nucleated RBCs: Immature red blood cells; seen in severe hemolytic anemias and bone marrow stress.
• Microcytes: Small RBCs; seen in iron deficiency anemia and thalassemia.
• Hypochromia: Pale RBCs due to low hemoglobin; seen in iron deficiency anemia and thalassemia.
• Target Cells: Bullseye appearance; seen in liver disease, thalassemia, and hemoglobinopathies.
• Basophilic Stippling: Fine granules in RBCs; seen in lead poisoning, thalassemia, and sideroblastic anemia.
• Sickle Cells: Crescent-shaped RBCs; seen in sickle cell disease.
• Schistocytes: Fragmented RBCs indicating mechanical damage; seen in DIC, TTP, and other hemolytic processes.

WBC Findings

• Neutrophilia: Increased neutrophils; seen in infections and inflammatory conditions.
• Left Shift: Presence of band cells indicating an active marrow response; seen in bacterial infections.
• Leukocytosis: Increased white blood cell count; seen in infections and inflammatory conditions.
• Generally Normal: No significant abnormalities.

Platelet Findings

• Thrombocytopenia: Low platelet count; seen in ITP, TTP, HUS, and DIC.
• Reactive Thrombocytosis: Elevated platelet count; seen in iron deficiency anemia.
• Large Platelets: Indicates increased production; seen in ITP.
• Generally Normal: No significant abnormalities.

This table summarizes the typical findings for each condition, providing a quick reference for interpreting peripheral blood smears in various pediatric hematologic disorders.

---

Grading System for Qualitative Analysis

• Percentage of cells affected in high-power field:
  • 1+: 25%
  • 2+: 25-50%
  • 3+: 50-75%
  • 4+: 75-100%

This grading system is used to quantify the extent of various abnormalities seen in RBCs, WBCs, and platelets.

Red Blood Cells (RBCs)

Using the provided image, here's a detailed examination of RBC morphology:

Size Variation (Anisocytosis)

• Normal: Standard size RBCs without significant variation.
• Microcyte: Smaller than normal RBCs.
• Macrocyte: Larger than normal RBCs.

Hemoglobin Distribution

• Hypochromia: RBCs with reduced hemoglobin content.
• Polychromasia: RBCs with a bluish tint, indicating immature red cells (reticulocytes).

Shape Variation (Poikilocytosis)

• Target Cell: RBCs with a bullseye appearance, often seen in liver disease, thalassemia, and hemoglobinopathies.
  • Why: These cells indicate abnormal hemoglobin content or structural integrity.
  • Additional Conditions: Iron deficiency anemia, post-splenectomy states.
• Acanthocyte: Spur cells with irregular projections, seen in liver disease, abetalipoproteinemia, and lipid disorders.
  • Why: Due to altered lipid composition in the RBC membrane.
  • Additional Conditions: McLeod syndrome.
• Spherocyte: Small, dense, and round RBCs without central pallor, typical of hemolytic anemias like hereditary spherocytosis and ABO incompatibility.
  • Why: Due to membrane protein defects or immune-mediated damage.
  • Additional Conditions: Autoimmune hemolytic anemia.
• Helmet Cell: Fragmented RBCs, often seen in microangiopathic hemolytic anemias (MAHAs) such as DIC, TTP, and HUS.
  • Why: Mechanical damage as RBCs pass through microvascular abnormalities.
  • Additional Conditions: Severe burns.
• Ovalocyte (aka Elliptocyte): Oval-shaped RBCs, seen in hereditary elliptocytosis and various anemias.
  • Why: Due to membrane protein defects.
  • Additional Conditions: Iron deficiency anemia, myelodysplastic syndromes.
• Schistocyte: Fragmented RBCs indicating mechanical damage, seen in DIC, TTP, and other hemolytic processes.
  • Why: Shearing forces in the vasculature.
  • Additional Conditions: Mechanical heart valves.
• Stomatocyte: RBCs with a mouth-shaped area of central pallor, seen in hereditary stomatocytosis and liver disease.
  • Why: Altered ion content within RBCs affecting membrane shape.
  • Additional Conditions: Alcoholic liver disease.
• Tear Drop: RBCs shaped like teardrops, seen in myelofibrosis and other marrow infiltration disorders.
  • Why: Mechanical distortion during RBC development.
  • Additional Conditions: Thalassemias.
• Sickle Cell: Crescent-shaped RBCs, seen in sickle cell disease.
  • Why: Abnormal hemoglobin (HbS) polymerization under low oxygen conditions.
  • Additional Conditions: None.
• Burr Cell: RBCs with short, evenly spaced projections, seen in uremia, liver disease, and pyruvate kinase deficiency.
  • Why: Altered cell membrane due to metabolic or environmental factors.
  • Additional Conditions: Gastric cancer.

Inclusions

• Pappenheimer Bodies: Iron-containing granules in RBCs, seen in sideroblastic anemia and post-splenectomy.
  • Why: Abnormal iron metabolism within RBCs.
  • Additional Conditions: Myelodysplastic syndromes.
• Cabot's Ring: Ring-shaped structures in RBCs, seen in severe anemia and lead poisoning.
  • Why: Remnants of mitotic spindle.
  • Additional Conditions: Pernicious anemia.
• Basophilic Stippling: Coarse granules in RBCs, seen in lead poisoning, thalassemia, and sideroblastic anemia.
  • Why: Aggregated ribosomal RNA.
  • Additional Conditions: Alcohol abuse.
• Howell-Jolly Bodies: Nuclear remnants in RBCs, seen in asplenia or after splenectomy.
  • Why: Failure to remove nuclear remnants.
  • Additional Conditions: Severe anemia.

Red Cell Distribution

• Agglutination: Clumping of RBCs, often due to cold agglutinins or autoimmune hemolytic anemia.
  • Why: IgM antibody-mediated RBC clumping.
  • Additional Conditions: Mycoplasma pneumonia, infectious mononucleosis.
• Rouleaux: Stacking of RBCs like coins, seen in high protein states like multiple myeloma and chronic inflammatory states.
  • Why: Increased plasma proteins (IgG) decreasing zeta potential.
  • Additional Conditions: Waldenström's macroglobulinemia, Multiple myeloma

White Blood Cells (WBCs)

• Count and Distribution: Estimate the relative proportions of different WBC types.
  • Neutrophils: Usually the most abundant, look for segmentation (bands and segmented).
  • Lymphocytes: Smaller with a large nucleus.
  • Monocytes: Larger cells with a folded or indented nucleus.
  • Eosinophils: Bilobed nucleus with red-orange granules.
  • Basophils: Bilobed or S-shaped nucleus with dark blue granules.
• Morphology: Check for any abnormal features.
  • Toxic Granulation: Coarse granules in neutrophils, indicating severe infection or inflammation.
  • Atypical Lymphocytes: Larger with abundant cytoplasm, seen in viral infections like infectious mononucleosis.
  • Blast Cells: Large immature cells, indicating leukemia.
  • Band Cells: Immature neutrophils, indicative of a left shift often seen in bacterial infections.

Platelets

• Count: Estimate the number of platelets. Generally, 1 dot in high power field (HPF) x 15,000 is roughly equivalent to the platelet count (e.g., 10 dots in HPF approximately equals 150,000 platelets).
  • Thrombocytopenia: Low platelet count.
  • Thrombocytosis: High platelet count.
• Morphology: Examine the size and appearance.
  • Normal: Small, disc-shaped.
  • Giant Platelets: Seen in some myeloproliferative disorders.
  • Clumping: Platelet clumps can falsely lower automated counts.

Example Interpretations in Pediatric Ward

ABO Incompatibility

• RBC Findings:
  • Spherocytes 3+: Small, dense RBCs without central pallor.
  • Polychromasia 2+: Bluish-tinted cells, indicating increased reticulocytes.
  • Nucleated RBCs (NRBCs) 1+: Presence of immature red blood cells.
• WBC Findings:
  • Neutrophilia 2+: Increased neutrophils, possibly with toxic granulation.
  • Left Shift: Presence of band cells, indicating an active marrow response.
• Platelet Findings:
  • Normal Count and Morphology: Platelets typically appear normal.

Iron Deficiency Anemia

• RBC Findings:
  • Microcytes 2+: Small RBCs.
  • Hypochromia 2+: Pale RBCs due to low hemoglobin.
  • Target Cells 1+: Occasionally seen.
• WBC Findings:
  • Generally normal unless there's concurrent infection.
• Platelet Findings:
  • Often elevated (reactive thrombocytosis).

Thalassemia

• RBC Findings:
  • Microcytes 3+: Small RBCs.
  • Hypochromia 3+: Pale RBCs.
  • Basophilic Stippling 2+: Fine granules in RBCs.
  • Target Cells 3+: Commonly seen.
• WBC Findings:
  • Generally normal unless there's concurrent infection.
• Platelet Findings:
  • Generally normal.

Sickle Cell Disease

• RBC Findings:
  • Sickle Cells 3+: Crescent-shaped RBCs.
  • Target Cells 2+: Bullseye appearance.
  • Polychromasia 2+: Increased reticulocytes.
• WBC Findings:
  • Leukocytosis during vaso-occlusive crises.
• Platelet Findings:
  • Generally normal.

Hereditary Spherocytosis

• RBC Findings:
  • Spherocytes 3+: Small, dense RBCs without central pallor.
  • Polychromasia 2+: Bluish-tinted cells.
• WBC Findings:
  • Generally normal unless there's concurrent infection.
• Platelet Findings:
  • Generally normal.

Immune Thrombocytopenic Purpura (ITP)

• RBC Findings:
  • Generally normal.
• WBC Findings:
  • Generally normal.
• Platelet Findings:
  • Thrombocytopenia: Low platelet count.
  • Large platelets: Indicates increased production.

Thrombotic Thrombocytopenic Purpura (TTP)

• RBC Findings:
  • Schistocytes 2+: Fragmented RBCs.
• WBC Findings:
  • Generally normal.
• Platelet Findings:
  • Thrombocytopenia: Low platelet count.

Hemolytic Uremic Syndrome (HUS)

• RBC Findings:
  • Schistocytes 2+: Fragmented RBCs.
• WBC Findings:
  • Generally normal.
• Platelet Findings:
  • Thrombocytopenia: Low platelet count.

Disseminated Intravascular Coagulation (DIC)

• RBC Findings:
  • Schistocytes 3+: Fragmented RBCs.
• WBC Findings:
  • Variable, often leukocytosis.
• Platelet Findings:
  • Thrombocytopenia: Low platelet count.