What is the significance of a peripheral blood smear showing a mild elevation in white blood cell (WBC) count due to neutrophilia, mild anisopoikilocytosis in red blood cells (RBCs), and an elevated platelet count?

Interpretation of Peripheral Blood Smear Findings

The peripheral blood smear shows a reactive neutrophilic leukocytosis with thrombocytosis and mild red blood cell changes, most likely representing an inflammatory or stress response.

Analysis of Blood Smear Components

White Blood Cells (WBCs)

• Mildly elevated WBC count primarily due to neutrophilia
• Neutrophils show normal cytoplasmic granularity and nuclear lobation
• No circulating metamyelocytes, myelocytes, or blasts
• Normal mature lymphocytes and monocytes without significant increase
• Inconspicuous eosinophils and basophils

Red Blood Cells (RBCs)

• Mild anisopoikilocytosis (variation in size and shape)
• No other significant RBC abnormalities noted

Platelets

• Elevated platelet count with occasional larger platelets

Clinical Significance

Neutrophilic Leukocytosis

Neutrophilic leukocytosis without immature forms or dysplastic changes suggests:

• Inflammatory response: The most common cause of neutrophilia with normal morphology 1
• Stress response: Surgery, trauma, exercise, or emotional stress can cause acute leukocytosis 2
• Infection: Particularly bacterial infections commonly present with neutrophilia 1

The absence of immature granulocytes (metamyelocytes, myelocytes) and blasts makes a hematologic malignancy less likely 3.

Thrombocytosis

Elevated platelet count with occasional larger platelets is consistent with:

• Reactive thrombocytosis: Common in inflammatory conditions, infections, and following acute blood loss 1
• Secondary thrombocytosis: Can occur with iron deficiency, inflammatory conditions, or post-splenectomy 1

Mild Anisopoikilocytosis

Mild variation in RBC size and shape may indicate:

• Mild anemia of chronic disease: Often seen with inflammatory conditions 1
• Early iron deficiency: Can present with mild RBC changes before anemia develops

Differential Diagnosis

1. Inflammatory/Infectious Process:

   • Bacterial infection (most common cause of neutrophilic leukocytosis) 1
   • Inflammatory disorders (e.g., rheumatoid arthritis, inflammatory bowel disease)

2. Physiologic Stress Response:

   • Surgery, trauma, exercise, emotional stress 2
   • Medications (e.g., corticosteroids, epinephrine)

3. Less Likely Considerations:

   • Early myeloproliferative neoplasm: The absence of dysplastic features and immature cells makes this less likely 4
   • Chronic neutrophilic leukemia: Would typically show higher WBC counts (>25,000/μL) 5

Recommendations for Further Evaluation

1. Clinical correlation is essential:

   • Evaluate for signs and symptoms of infection or inflammation
   • Review medication history for drugs that can cause leukocytosis
   • Assess for recent stressors, surgery, or trauma

2. Laboratory follow-up:

   • Repeat CBC in 2-4 weeks to monitor for persistence of findings
   • If persistent leukocytosis and thrombocytosis, consider:
     • Inflammatory markers (ESR, CRP)
     • Blood cultures if infection suspected
     • Iron studies if anemia develops

3. When to consider hematology referral:

   • If leukocytosis persists >3 months without clear cause
   • If immature cells appear in subsequent blood smears
   • If cytopenias develop
   • If significant clinical symptoms (fever, weight loss, night sweats) develop 3

Conclusion

The peripheral blood smear shows a reactive pattern with neutrophilic leukocytosis, thrombocytosis, and mild RBC changes. This pattern is most consistent with an inflammatory or stress response rather than a primary hematologic disorder. Clinical correlation and follow-up testing are recommended to identify the underlying cause and monitor for resolution.