MLT GlobeHematology: WBC morphology & differential – page 2
109 Hematology MCQs on WBC morphology & differential with answers and explanations.
The primary lymphoid organs where lymphocytes develop are the:
B cells develop in bone marrow and T cells mature in the thymus. Spleen, nodes and tonsils are secondary organs where mature lymphocytes meet antigen.
A teenager with fever, sore throat and lymphadenopathy has many large lymphocytes with abundant blue cytoplasm that 'scallops' around red cells. The best next test is:
These are reactive (Downey) lymphocytes, typical of infectious mononucleosis caused by EBV. A heterophile antibody test or EBV serology confirms it.
Toxic granulation, Döhle bodies and cytoplasmic vacuoles in neutrophils most suggest:
These are reactive changes in neutrophils during severe infection or inflammation. Vacuoles in particular suggest bacteremia.
In granulocyte maturation, secondary (specific) granules first appear at which stage?
Specific granules first appear in the myelocyte, allowing neutrophil, eosinophil and basophil lines to be told apart. Promyelocytes contain mainly primary (azurophilic) granules.
A marrow cell has a round nucleus with visible nucleoli, basophilic cytoplasm and many large reddish-purple granules, with a clear Golgi zone. It is a:
Abundant large primary azurophilic granules with nucleoli define the promyelocyte. Myeloblasts have few or no granules.
A granulocyte precursor with a kidney-bean (indented) nucleus, condensed chromatin, no nucleoli and pink secondary granules is a:
The metamyelocyte has an indented, kidney-shaped nucleus with indentation less than half the nuclear width. A myelocyte nucleus is round or oval.
A large cell has a folded, horseshoe-shaped nucleus with lacy chromatin and grey-blue 'ground-glass' cytoplasm with fine granules and vacuoles. It is most likely a:
Monocytes have folded nuclei, lacy chromatin and grey-blue cytoplasm with fine azurophilic dust and vacuoles. Reactive lymphocytes have deeper blue cytoplasm and denser chromatin.
A 10-year-old from a rural area has abdominal pain and an eosinophil count of 3.2 × 10^9/L. The most likely cause is:
Tissue-invasive helminths are the leading cause of eosinophilia worldwide. Acute bacterial infection and corticosteroids usually lower eosinophils.
A WBC count is 12.0 × 10^9/L and the differential shows 55% lymphocytes. The absolute lymphocyte count is:
Absolute count = WBC × percentage = 12.0 × 0.55 = 6.6 × 10^9/L. Reporting only the percentage can hide true absolute changes.
A cell with an eccentric round nucleus, coarse 'clock-face' chromatin, deep blue cytoplasm and a pale area next to the nucleus is a:
Plasma cells have eccentric nuclei, clumped chromatin and a perinuclear hof (Golgi zone) in basophilic cytoplasm. Myelocytes contain granules and lack clock-face chromatin.
Which feature best identifies a myeloblast on a Wright-stained smear?
Myeloblasts have fine chromatin, 2–5 nucleoli, a high N:C ratio and few or no granules. A perinuclear hof with clumped chromatin describes a plasma cell.
A small drumstick-shaped nuclear appendage seen on a few neutrophils represents:
The neutrophil drumstick is the inactivated X chromosome, seen in females. Howell-Jolly bodies are nuclear remnants in red cells.
The usual adult reference interval for the total white cell count is about:
Most adult WBC reference intervals are about 4.0–11.0 × 10^9/L (4000–11 000/µL); exact limits vary slightly by lab. 150–400 × 10^9/L is the platelet reference interval.
A WBC count is 8.0 × 10^9/L and monocytes are 15% on the differential. The absolute monocyte count and interpretation are:
Absolute count = 8.0 × 0.15 = 1.2 × 10^9/L. Adult monocytes are usually below about 1.0 × 10^9/L, so this is an absolute monocytosis.
The large orange-red granules of eosinophils contain a toxic protein that damages helminths. It is:
Eosinophil specific granules contain major basic protein, eosinophil cationic protein and eosinophil peroxidase. Histamine is mainly stored in basophil and mast cell granules.
In adult peripheral blood, which lymphocyte subset is normally the largest?
About 60–80% of circulating lymphocytes are T cells, 10–20% B cells and 5–15% NK cells. Plasma cells are normally absent from blood.
A patient with advanced HIV infection is most likely to show which lymphocyte result by flow cytometry?
HIV destroys CD4+ T helper cells, so the CD4 count falls and the CD4:CD8 ratio (normally about 1–3) is reversed. Absolute CD4 counts guide staging and prophylaxis.
A full-term newborn has a WBC of 22 × 10^9/L with mostly neutrophils on day 1 and no signs of infection. The best interpretation is:
Newborns normally have high WBC counts (about 9–30 × 10^9/L) with neutrophil predominance in the first days, falling over the first weeks. Lymphocytes then predominate in early childhood.
On a 5-part automated differential using flow cytometry, side-scattered light mainly reflects:
Forward scatter relates to cell size, and side scatter to internal structure such as granules and nuclear lobes; eosinophils and neutrophils have high side scatter. Antigens need labeled antibodies.
An analyzer flags 'blasts?' on a sample with a normal-looking scatter plot. According to good practice, the technologist should:
Suspect flags have limited specificity, so a smear review confirms or excludes abnormal cells. Rerunning or diluting does not answer the morphologic question.