MLT GlobeHematology: WBC morphology & differential
109 Hematology MCQs on WBC morphology & differential with answers and explanations.
On a Wright-stained film, how many nuclear lobes does a normal mature segmented neutrophil usually have?
Mature neutrophils typically show 2–5 lobes joined by thin filaments. Six or more lobes (hypersegmentation) suggests megaloblastic anemia; a bilobed spectacle shape suggests Pelger–Huët anomaly.
During a 100-cell differential on a healthy adult, which leukocyte is the least frequently encountered?
Basophils make up only about 0–1% of circulating leukocytes, so a normal differential may show none. Neutrophils and lymphocytes are the most common.
Which leukocyte is the most numerous in adult blood and contains primary, secondary and tertiary granules?
Neutrophils make up about 40–75% of leukocytes and carry azurophilic (primary), specific (secondary) and gelatinase (tertiary) granules. Lymphocytes are agranular.
After antigen stimulation, B lymphocytes differentiate into which cell that secretes large amounts of antibody?
Activated B cells become plasma cells, with abundant rough endoplasmic reticulum for immunoglobulin production. Some form memory B cells; T cells do not secrete antibody.
Which finding defines neutropenia?
Neutropenia is judged on the absolute neutrophil count (total WBC × neutrophil fraction), commonly below 1.5 × 10^9/L in adults; total WBC may be low for other reasons.
While scanning a normal blood film, which leukocyte is typically the largest?
Monocytes measure about 12–20 µm with abundant grey-blue cytoplasm and a folded nucleus; neutrophils and eosinophils are about 10–15 µm, small lymphocytes about 7–10 µm.
A child with heavy hookworm infection is likely to show which leukocyte change on the differential?
Tissue-invasive helminths drive IL-5 production, raising eosinophil counts. Hookworm may also cause iron deficiency anemia, but eosinophilia is the typical leukocyte change.
A patient with acute bacterial pneumonia has an absolute neutrophil count of 14 × 10^9/L. What term describes this?
Neutrophilia is an absolute neutrophil count above the reference interval. A leukemoid reaction implies an extreme count (often >50 × 10^9/L); right shift means hypersegmentation.
On a Romanowsky-stained film, neutrophils, eosinophils and basophils are told apart mainly by what?
Neutral (lilac), acidophilic (orange-red) and basophilic (dark purple) specific granules identify the three granulocytes; all have nuclei and overlap in size.
Which leukocyte releases major basic protein to attack helminth larvae too large to be phagocytosed?
Eosinophils attach to antibody-coated helminths and release toxic granule proteins such as major basic protein and eosinophil cationic protein.
Which surface marker is found on T lymphocytes but not on B lymphocytes?
CD3 is part of the T-cell receptor complex and identifies T cells. CD19, CD20 and CD79a are B-cell markers used in flow cytometry.
A leukocyte has 3–5 nuclear lobes and pale lilac cytoplasm with fine granules. What is it?
Segmented nucleus plus fine neutral granules identify the neutrophil. Basophils have coarse dark granules, monocytes a folded nucleus, lymphocytes a round nucleus.
A leukocyte on a film has coarse dark purple granules that largely hide a lobed nucleus. What is it?
Basophils contain large dark granules of histamine and heparin that cover the nucleus. Lymphocytes are agranular; reticulocytes have no nucleus.
Kupffer cells in the liver are tissue macrophages derived from which blood leukocyte?
Monocytes leave the blood and become resident macrophages, such as Kupffer cells in the liver and alveolar macrophages in the lung.
After centrifuging anticoagulated blood, which cells settle at the bottom because of their highest density?
Red cells are the densest and form the bottom layer; leukocytes and platelets form the buffy coat above them, with plasma on top.
Where do the stem cells that give rise to both T and B lymphocytes originate?
Lymphoid progenitors arise from marrow stem cells. B cells mature in the marrow; T-cell precursors migrate to the thymus to mature.
A patient with a high fever has leukocytosis, neutrophilia and toxic granulation. Which infection is most likely?
Acute bacterial infections typically raise neutrophils with a left shift and toxic changes. Viral infections usually cause lymphocytosis.
Which feature describes a normal blood basophil?
Basophils are under 1% of leukocytes and have coarse, water-soluble dark granules overlying a bilobed or irregular nucleus. Orange-red granules identify eosinophils.
Which feature identifies a mature segmented neutrophil on a Wright-stained smear?
Neutrophils have a segmented nucleus and fine lilac granules and form about 40–75% of adult leukocytes. Metachromatic granules suggest basophils; agranular blue cytoplasm suggests lymphocytes.
Which feature identifies an eosinophil on a Romanowsky-stained smear?
Eosinophils have acidophilic granules staining with eosin and a bilobed nucleus; they are about 1–6% of leukocytes. Dark purple masking granules indicate basophils.