WBC Lecture 2: BM, NON-Malignant WBC Disorders

Cellularity, maturation of myeloid & erythroid series (M:E ratio), cell distribution (Differential), eosinophils / basophils, megakaryocytes

Presence of other cells: Lymphocytes, plasma cells, histiocytes, osteoclasts, fibroblasts, iron stores, abnormal infiltrates, and fibrosis

Relative cellularity, differential and M:E, iron stores, megakaryocyte evaluation, metastatic tumor cells, and lymphoid aggregates

Examined under low power (x10) to detect presence of spicules

Spicule is relatively intact marrow consisting of hematopoietic and stromal cells; stain dark blue/purple

General cellularity, abnormal cell clusters, and quality of aspirate using megakaryocytes

Performed under x100 magnification; 300–500 nucleated cells are counted

All nucleated cells: myeloid series – blasts – segs (neut, eos, baso), erythroid series, lymphs, monos, plasma cells, and early cells as well

It is a more reliable differential and determines the M:E ratio

Most cells in the normal BM consist of myeloid and erythroid

All stages of development should be present but within their anticipated distribution

Count and differentiate all cell lines and maturation stages

Derived from the differential; normal M:E ratio is 1.5:1 – 3.3:1

The granulopoietic tissue occupies 1.5 to 3.3 times more space than the erythroid precursors as a result of shorter survival of granulocytes in the circulation

Iron reported as absent, decreased, adequate, moderately increased, or markedly increased

By the number seen per low power field (10x); 2–10/lpf is normal

They are too unevenly distributed to count in differential

Clusters may indicate hyperplasia; fewer than 2 megakaryocytes/LPF may indicate hypoplasia or poor quality aspirate

Cellularity is the ratio of all nucleated hematopoietic cells (ANC) to fat cells

Cellularity in adults is approximately 50% (1:1)

100 – age ±10

Reported as increased, normal, or decreased

Normal 1:1

Hypercellular marrow 10:1

Hypocellular marrow 1:10

Patient history, age, sex, description of samples received

CBC, ESR, reticulocyte count, manual differential, PBS

Differential count, description of the cellularity, M:E ratio, status of the iron stores, description of histological sections of biopsy and diagnostic conclusion.

sample report includes normal values for HGB, HCT, MCV, MCH, WBC, platelet; abbreviations PB (peripheral blood), BMA (bone marrow aspirate), BMBX (bone marrow biopsy), DX (diagnosis)

Spicule

Myeloid Precursors

Early and late megakaryocytes

Megakaryocyte, plasma cells, neutrophils, band and metas, NRBC & slightly earlier RBC

Lack of mature neuts.
Very hypercellular – monotonous cell population.

Mostly blasts

Megaloblastic anemia RBC precursors

Plasma cells

A benign shift in neuts from marginal into circulatory pool

Stress, trauma, labor, strenuous exercise, shock, burns, or increase in epinephrine

Pathological conditions shift in neuts from marginal into circulatory pool, increased BM production, release of neutrophils from storage pool to PB, infection

Left shift describes an increased number of immature cells as an indicator of infection

Bands, metamyelocytes, and possibly myelocytes

Increased release from storage pool; usually seen with neutrophilia and toxic changes

A reactive leukocytosis above 50 × 10³/microL with neutrophilia and a marked left shift; bands and often metas/myelos, could have rare pro or blast

Severe and/or chronic infection (TB, pneumonia), metabolic disease, inflammation, response to a malignancy

Leukoerythroblastic picture

Presence of immature neutrophils, nRBCs, and teardrop RBCs in the same sample

Often accompanied by neutrophilia, but not always

Possibility of a space-occupying lesion in the bone marrow

Metastatic tumor, fibrosis, lymphoma, leukemia

Nucleus and/or cytoplasm

They may be acquired or inherited

Hyposegmentation, hypersegmentation, pyknotic forms, and necrobiotic forms

Toxic granulation, degranulation, vacuolization (with or without engulfed matter) and Döhle bodies

Chronic infections, megaloblastic anemia, and drugs

Myelodysplastic syndromes. Asynchrony of nuclear maturation (Very clumped chromatin and No segmentation)

‘Dying’ cell with nucleus very dark/dense, filaments still visible

Dead cell with no filaments

Neutrophilic cytoplasmic abnormalities with absence of granules (hypo- or agranular, “degranulation,”) and abnormal granules

Toxic granulation, Döhle bodies, and cytoplasmic vacuoles

While these changes may be considered “abnormal,” they usually reflect a normal, reactive response

Often seen with toxic granulation, it can indicate phagocytosis and may contain bacteria or other material

Pale blue, oval inclusions at periphery; grey to light blue on Wright stain

Only neutrophils

Remnants of ribosomal RNA. Bacterial infection, sepsis, and pregnancy.

Histoplasma capsulatum, platelet satellitism, yeast, and bacilli

Pelger-Huët anomaly, Alder-Reilly anomaly, May-Hegglin anomaly, and Chediak-Higashi syndrome

Hyposegmentation of the neutrophil nucleus. Autosomal dominant

It is asymptomatic and fully functional

Bi-lobed nucleus, dense heterochromatin, incomplete nuclear segmentation, also called “dumbbell” or “pince-nez”

Nucleus is round or oval with no segmentation (rare)

Exceptionally coarse and condensed, showing it is a mature cell

Band or myelocyte

70 to 90% of neutrophils are affected

A drug-induced form of Pelger-Huët. Seen in HIV, tuberculosis, Mycoplasma pneumonia, and severe bacterial infections

Myelodysplastic syndromes, acute leukemias, and chronic myeloproliferative disorders

Autosomal recessive

Abnormally large metachromatic granules in the cytoplasm of granulocytes, monocytes, and lymphocytes

Incomplete degradation of mucopolysaccharides (Mucopolysaccharide deposits (granules) in most cells)

Leukocyte function is unaffected

Deep-purple to lilac granules

Promyelocytes or heavy toxic granulation

Neutrophilia, Döhle bodies, and left shift = toxic granulation; Alder-Reilly granules can also be found in lymphocytes and monocytes

Very rare

Giant and bizarre platelets that may be hypogranular

Autosomal dominant (rare)

Platelet disorder

Leukopenia with large basophilic inclusions

Variable thrombocytopenia with giant platelet forms

Patients are usually asymptomatic or have mild bleeding disorders

Autosomal recessive. Rare and fatal.

Characterized by abnormal fusion of granules in most cells that contain granules throughout the body

Large and mostly dysfunctional

Hematopoietic cells are affected

Hair, skin, adrenal and pituitary glands, and nerves

Dysfunctional phagocytosis and inefficient bacterial destruction. Increased susceptibility to infection (immunodeficient), albinism and peripheral neuropathy.

Platelet dense granule abnormality which has a tendency to bleed

Variable albinism

Neurologic complications develop through childhood

Giant lysosomal granules in all WBCs

A rare X-linked or autosomal recessive condition

Usually normal

Decreased ability to produce NADPH oxidase needed to kill microorganisms

Recurring bacterial and fungal infections

They are not killed on ingestion but remain encased in granulomas to localize them

Rupture and release live bacteria and pus

Normal morphology or neutrophilia with toxic changes as seen in bacterial infection

Nitroblue tetrazolium (NBT) reduction test or flow cytometry

Reactive changes during infection, recovery from BM aplasia or post GM-CSF

Nuclear contortion, increased cytoplasmic volume, and increased numbers of cytoplasmic granules

Cytoplasmic vacuolation, intracellular debris, and irregular cytoplasmic borders

Lysosomal storage diseases

Enzyme deficiencies

It accumulates in cells due to incomplete degradation. Seen in macrophages and monocytes found in BM & spleen.

Most common lysosomal lipid storage disease. Unmetabolized lipid accumulates in the macrophages throughout the body.

The BM contains Gaucher cells, macrophages that have abundant fibrillar blue gray cytoplasm with a wrinkled appearance.

Lipid buildup in macrophages. The BM contains Niemann-Pick cells, macrophages that contain foamy cytoplasm packed with lipid-filled lysosomes that appear as vacuoles after staining

Epstein-Barr Virus (EBV). EBV infects >90% of world population (usually young children).

B lymphocytes by attaching to CD21 receptors

Lymphocyte proliferation including NK cells, T CD4, and T CD8

Production of heterophile antibodies in serum (react with RBCs from horse or sheep: principle of Mono test)

Reactive lymphocytes

Usually elevated (10–30 × 10⁹/L)

Absolute lymphocytosis

Wide variation in morphology