DLC labelled microscope image and key features Presentation_

Microscopic features of differential leucocytiv count

1. Differential Leucocyte Count (DLC) Peripheral Blood Film (PBF) Examination

2. Objectives • Understand examination of blood film for DLC • Learn morphology of mature leucocytes • Know normal ranges of leucocytes • Study methods: manual & automated • Recognize pathologic variations

3. Examination of PBF for DLC • Select junction of body and tail of smear • Avoid rouleaux formation and scattered RBCs • Count 100 WBCs and classify types • Express results as % of P, L, M, E, B • Count systematically, avoid zigzag method • Use DLC counter if available

4. Normal Values of DLC (Adults) • Neutrophils: 40–75% (2,000–7,500/µl) • Lymphocytes: 20–40% (1,500–4,000/µl) • Monocytes: 2–10% (200–800/µl) • Eosinophils: 1–6% (40–400/µl) • Basophils: 0–1% (10–100/µl)

5. Morphologic Features of Mature Leucocytes Feature Neutrophil Lymphocyte (small & large) Monocyte Eosinophil Basophil Cell Diameter 12–15 µm Small: 9–12 µm Large: 12–16 µm 12–20 µm 12–15 µm 12–15 µm Nucleus 2–5 lobed, clumped chromatin Large nucleus, round/indented, clumped chromatin Large, lobulated, indented, with fine chromatin Bilobed, clumped chromatin Bilobed, clumped chromatin Cytoplasm Pink/violet granules Peripheral rim of basophilic cytoplasm, no granules Light basophilic, may have vacuoles Coarse crimson red granules Large coarse purplish granules obscuring nucleus Normal % 40–75 20–40 2–10 1–6 0–1 Absolute Count/µl 2,000–7,500 1,500–4,000 200–800 40–400 10–100

6. Methods of DLC 1. Manual (visual) counting: • Examine stained peripheral smear • Identify morphology of WBCs • Count 100 cells 2. Automated counting: • Based on cell size & cytochemistry • Flow cytometry • Pattern recognition • Limitation: NRBCs may be misclassified

7. Pathologic Variations - Neutrophils • Neutrophilia: >7,500/µl – Bacterial infections, stress, steroids, CML • Neutropenia: <2,000/µl – Viral infections, drugs, marrow failure, sepsis

8. Neutrophilia

9. Pathologic Variations - Lymphocytes & Monocytes • Lymphocytosis: >4,000/µl – Viral infections, TB, CLL • Lymphopenia: <1,500/µl – HIV, steroids, irradiation • Monocytosis: >800/µl – Chronic infections, autoimmune disorders, leukemias

10. Lymphocytosis

11. Pathologic Variations - Eosinophils & Basophils • Eosinophilia: >400/µl – Allergies, asthma, parasitic infestations, skin & lung diseases • Eosinopenia: often due to steroid therapy • Basophilia: >100/µl – CML, polycythemia vera, Hodgkin’s disease

12. Take Home Message • DLC gives distribution of different WBC types • Essential for diagnosis of infections, allergies, malignancies • Reference ranges must be considered • Both manual & automated methods available • Pathologic variations help clinical correlation

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18. Causes of Neutrophilia • Acute bacterial infections (pneumonia, abscess) • Inflammatory conditions (rheumatoid arthritis, gout) • Tissue necrosis (myocardial infarction, burns) • Stress, exercise, corticosteroid therapy • Myeloproliferative disorders (CML, polycythemia vera)

19. Causes of Lymphocytosis • Viral infections (infectious mononucleosis, mumps, rubella) • Chronic bacterial infections (tuberculosis, pertussis, brucellosis) • Post-vaccination response • Autoimmune disorders (thyrotoxicosis) • Chronic lymphocytic leukemia (CLL) and other lymphoid malignancies

20. Causes of Monocytosis • Chronic bacterial infections (TB, syphilis, brucellosis, endocarditis) • Protozoal & rickettsial infections (malaria, kala-azar, rickettsiosis) • Recovery phase of acute infections • Hematologic malignancies (CMML, AML) • Autoimmune diseases (SLE, rheumatoid arthritis, ulcerative colitis)

21. Causes of Eosinophilia • Allergic disorders (asthma, hay fever, urticaria, drug reactions) • Parasitic infestations (filaria, roundworm, hookworm, malaria) • Skin diseases (eczema, pemphigus, dermatitis herpetiformis) • Lung diseases (Löffler’s syndrome, tropical eosinophilia) • Malignancies (Hodgkin’s lymphoma, some leukemias)

22. Causes of Basophilia • Myeloproliferative disorders (CML, polycythemia vera, myelofibrosis) • Allergic reactions (rare contributor) • Hypersensitivity reactions • Hypothyroidism • Ulcerative colitis and chronic inflammatory states