Bone Marrow-nonneoplastic
Last revised 15 February 2008
Last major update December 2006
Copyright © 2001-2008 PathologyOutlines.com, Inc.
See also Leukemia-acute, Chronic myeloid neoplasms
Lymphoma-B cell, Lymphoma-non B cell, Bone, Hematology (future topic)
Bold and underlined topics are hypertext links
References in green are journals with free full text
Table of contents
Primary references, embryonic development
Normal: general, basophils, eosinophils, erythroid maturation, hematogones, lymphocyte maturation, mast cells, megakaryocyte maturation, monocyte maturation, neutrophil maturation, osteoblasts, osteoclasts, plasma cells, age related changes
Bone marrow biopsy and aspirate smear: technique, sample report, routine stains
Alterations in cellularity: cellularity-general, amegakaryocytic thrombocytopenia, aplastic anemia, Diamond-Blackfan anemia, dyskeratosis congenita, Fanconi’s anemia, hypercellular, Schwachman-Diamond syndrome, TAR syndrome, pure red cell aplasia, treatment related
Benign changes: arsenic toxicity, gelatinous transformation, Howell-Jolly bodies, iron, lymphoid aggregates, necrosis, persistent polyclonal lymphocytosis, plasmacytosis, polymorphous reactive lymphoid hyperplasia, systemic polyclonal B-immunoblastic proliferation
Anemias: megaloblastic
Infectious/inflammatory: Candida, CMV, Cryptococcus, Denge fever, granulomatous inflammation, histoplasmosis, HIV/AIDS, human granulocytic anaplasmosis, Leishmania, malaria, mycobacteria, parvovirus B19, Penicilliosis marneffei, Q fever, sarcoidosis, Whipple’s disease
Systemic disorders: Chediak-Higashi syndrome, cystinosis, Fabry’s disease, Gaucher’s disease, mucopolysaccharidosis type VII, Niemann-Pick disease, Pearson's syndrome, sea-blue histiocytosis syndrome, sickle cell
Other toxicity / deposition disorders: alcohol abuse, calcium oxalate, copper, podophyllin
Bone marrow transplantation: general
American Journal of Clinical Pathology (AJCP), January 1975 to December 2006
American Journal of Surgical Pathology (AJSP), March 1977 to December 2006
Archives of Pathology and Laboratory Medicine (Archives), January 1976 to December 2006
Human Pathology (Hum Path), March 1970 to December 2006
Journal of Clinical Pathology, January 1966 to December 2006
Modern Pathology (Mod Path), January 1988 to January 2007
Biomed Center, to 19 December 2006
Mills: Sternberg's Diagnostic Surgical Pathology (4th ed), 2004
Rosai: Rosai and Ackerman's Surgical Pathology (9th ed), 2004
Tumors of the Bone Marrow (AFIP Atlas of Tumor Pathology, Series 3, Vol 9)
AFIP images (not copyrighted) courtesy of www.PathologyResources.com
Websites with images: American Society of Hematology, PathoPic, PEIR digital library
Journal search terms: marrow and each disease entity listed
Please refer to these primary references for more detailed discussions and photographs
Embryologic development of bone marrow
In embryo, hematopoiesis (other than lymphoid) occurs in yolk sac with formation of mesenchymal derived primitive erythroblasts
Aorta also contributes lymphomyeloid stem cells, as do embryonic liver and bone marrow (Development 2002;129:4147, Ann N Y Acad Sci 2005;1044:41)
At weeks 10 to 24, liver is primary hematopoietic organ with production of granulocytes and megakaryocytes in sinusoids
At months 4-5, bone marrow hematopoiesis begins
By birth, liver and spleen have minimal role in myelopoiesis, and bone marrow is major site of hematopoiesis
Diagram: blood islands in embryo
Micro images: yolk sac at 18 days; fetal liver at 17 weeks; fetal bone marrow at 19 weeks
References: Int J Dev Biol 2005;49:243, Wikipedia (stem cells)
Normal bone marrow
3-6% of total body weight
Major organ for hematopoiesis at birth; also primary and secondary lymphoid organ
Hematopoiesis sites change from axial and radial skeleton in newborns to flat bones of central skeleton by mid-teens
Pluripotent stem cells develop into myeloid blasts (myeloblasts, monoblasts, erythroblasts and megakaryoblasts) or lymphoblasts
Cells are in storage pools for 5-7 days, then to blood, then to tissues
Hematopoietic stem cells: defined as cells with multilineage hematopoietic differentiation potential and sustained self-renewal activity; detected by their ability to regenerate long-term multilineage hematopoiesis in myeloablated recipients
Diagram of hematopoietic cell differentiation #1; #2; diagram of myelopoiesis
Normal bone marrow differential in adults
Vasculature: nutrient (medullary) artery ramifies through marrow space to supply medullary cavity; its arterioles branch into capillaries that are continuous with thin walled sinusoids; sinusoidal walls have inner endothelial cells and outer adventitial reticular cells; outer adventitial reticular cells are phagocytic and can become lipocytes; also synthesize collagen, laminin, fibronectin and proteoglycans
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Micro: arterioles, venules, capillaries, sinusoids, adipose tissue, connective tissue and hematopoietic cells; mitotically active cells are usually paratrabecular and perivascular
Micro images-bone marrow biopsy: normal marrow #1; #2; #3; #4; #5; chart of erythropoiesis and granulopoiesis; CD15 staining of myeloid cells
aspirate smear: #1; #2; #3; #4 (cells are labeled); Sudan black staining
Virtual slides: aspirate smear
0.5% of all white blood cells
Progresses from myeloid stem cell to basophilic promyelocyte, to basophilic myelocyte, to basophilic metamyelocyte, to basophil
Similar to mast cells, but apparently generated by different CD34+ precursor cells in bone marrow
Leaves bone marrow as terminally differentiated granulocyte
Named because it stains with basic dyes
Basophils and mast cells are effecter cells in allergen/IgE-mediated immune responses; they induce type 1 immediate immune response in airways and elsewhere, causing bronchial asthma and other allergic diseases (Allergol Int 2006;55:105)
Also play a critical role in host defense against infection with helminthes (Allergol Int 2006;55:99)
Basophil activation test, using CD203c or CD63 as an activation marker, has become a reliable test for in vitro investigations of immediate allergy, complementing other in vitro tests (Clin Mol Allergy 2005;3:9)
Micro:
basophilic myeloblast: difficult to distinguish types of granulocyte blasts; large round cell with basophilic cytoplasm without granules; N/C ratio is 80%; dispersed chromatin with nucleolus
basophilic promyelocyte: intermediate in development between basophilic myeloblast and myelocyte; large round cell with a few undifferentiated cytoplasmic granules; slight chromatin clumping, nucleolus present
basophilic myelocyte: round/oval cell; minimal cytoplasm with slight basophilia, moderate cytoplasmic purple-black granules of varying size and shape; granules are usually larger than neutrophilic granules; N/C ratio is 50%; chromatin moderately condensed, no distinct nucleolus
basophilic metamyelocyte: oval cell with abundant pale cytoplasm with large and fairly uniform specific granules; N/C ratio is 40%; nucleus is small and indented with condensed chromatin, no nucleolus
basophil: smaller than other WBCs (10-15 microns); cytoplasm is homogenous pale-blue but often obscured by purple-blue granules (containing heparin and histamine); N/C is 20%; nucleus is often unsegmented or bilobed, chromatin is coarse
Micro images-bone marrow: basophilic promyelocyte; basophilic myelocyte #1; #2; #3; #4; #5; #6-CML; basophilic metamyelocyte #1; #2; #3; basophil #1; #2; #3; #4 with toluidine blue stain
peripheral blood: basophil #1; #2; #3; #4; #5; basophil precursors identified in CML; increased basophils in CML
Positive stains: commonly used - CD9, CD25, CD38; also CD11a, CD11b, CD11c, CD13, CD15u, CD17, CD18, CD26, CD31, CD32, CD33, CD35, CD38, CD43, CD44, CD45, CD46, CD47, CD49d, CD50, CD55, CD58, CD59, CD63, CD68, CD71 (dim by flow cytometry), CD85A, CD85H, CD87, CD88, CD99, CD102, CD116, CD121b, CD123, Cd125, CD126, CDw128a, CD203c, HLA-DR (immature basophils, Allergy 2006;61:1063), histidine decarboxylase, 2D7 (J Clin Pathol 2006;59:396), basogranulin (AJCP 2006;125:273)
Positive stains: allergic subjects - CD32, CD122, CD124, CD130, CD154 (J Allergy Clin Immunol 2000;106:1190)
Variable: CD14, CD15, myeloperoxidase
Negative stains: CD2, CD3, CD7, CDw12, CD16, CD19, CD20, CD21, CD22, CD23, CD56, CD57, CD114, CD122, CD124, tryptase
EM images: basophil
References: Wikipedia, Cytometry 1999;35:249-flow cytometry markers, Allergy 1994;49:861-markers, Blood 1987;70:1872-markers
1-4% of all white blood cells
Progresses from myeloid stem cell to eosinophilic promyelocyte, to eosinophilic myelocyte, to eosinophilic metamyelocyte, to eosinophil
Named because granules stain deeply with eosin
Have a role in response to parasitic infections and allergic conditions
Degranulation is strictly controlled, which allows it to differentially release its contents in an ordered manner, which prevents tissue injury during migration (Semin Respir Crit Care Med 2006;27:117)
Produces: IL-2, IL-3, IL4, IL-5, IL-7, IL-13, IL-16, tumor necrosis factor-alpha, transforming growth factor-beta, RANTES, eosinophil cationic protein, eosinophil peroxidase, eosinophil derived neurotoxin, major basic protein and Charcot-Leyden crystal lysophospholipase
Micro:
eosinophilic promyelocyte: intermediate in development between a myeloblast and myelocyte; 15 microns in diameter with large nucleus and nucleolus; contains a few undifferentiated (primary, coreless) cytoplasmic granules in intensely basophilic cytoplasm
eosinophilic myelocyte: round/oval large cells with moderate cytoplasm containing prominent primary purple granules and secondary red-orange, refractile granules of similar size; N/C ratio is 50% with moderately condensed chromatin and indistinct nucleolus
eosinophilic metamyelocyte: round/oval cells with abundant cytoplasm containing large blue-orange granules; N/C ratio is 40%; nucleus is indented with moderately condensed chromatin and no nucleolus
eosinophil: 9-15 microns with coarsely granular cytoplasm containing refractile orange granules grouped around a single, horseshoe shaped nucleus with 2-3 lobes
Micro images: developing eosinophils #1; #2; #3; eosinophilic promyelocyte #1; #2; #3; #4; eosinophilic precursors including eosinophilic myelocyte; eosinophilic myelocyte #1; #2; #3; eosinophilic myelocytes and metamyelocytes #1; #2; eosinophilic metamyelocyte #1; #2; #3; eosinophils #1; #2; #3
AML-M4e: various eosinophil precursors
Other: hypereosinophilic syndrome
peripheral blood: eosinophils #1; #2; #3; #4; #5; #6
Positive stains: CD9; also CD15, CD16, CD23, CD32, CD35, CD47R (weak), CD49d, CD50, CD52, CD62L, CD69, CD85A, CD85D, CD88, CD89, CD116, CDw125, CD183, myeloperoxidase, Sudan Black, PNL2
Negative stains: CD114, tryptase
EM images: normal eosinophil with crystalloid granules #1; #2; #3; #4-details of granules
References: Wikipedia, eMedicine
Erythroid maturation in bone marrow
Erythroid maturation (erythropoiesis) is characterized by increasing hemoglobin synthesis, decreasing cell size, decreasing cytoplasmic basophilia and extrusion of nucleus outside cell at orthochromatic stage of development
Progresses from myeloid stem cell to pronormoblast, to basophilic normoblast, to polychromatophilic normoblast, to orthochromatic normoblast (then extrusion of nucleus), to reticulocyte (young erythrocyte), to erythrocyte (red blood cell)
Early erythroid precursors cluster in islands randomly distributed throughout marrow but related to vascular structures
Erythroblast islands may be specialized niches where intercellular interconnections and cytokines regulate erythropoiesis (Curr Opin Hematol 2006;13:137)
Note: normoblast is also called erythroblast
Micro:
pronormoblast: 13-18 microns, round/ovoid with thin rim of basophilic cytoplasm, large spherical nucleus with fine chromatin and 1-2 nucleoli; usually perinuclear halo; N/C ratio is 90%
basophilic normoblast: 12-17 microns; increase in deeply basophilic cytoplasm compared to pronormoblast and slightly smaller nucleus with slight chromatin condensation; often perinuclear halo; no granules, no nucleolus; N/C ratio is 75%-85%
polychromatophilic normoblast: 12-15 microns; round/ovoid with abundant, dull gray to gray-green, variegated cytoplasm due to polyribosomes (basophilic) and hemoglobin (eosinophilic); round, condensed and basophilic nucleus has coarse granules that give it a checkboard (cart-wheel) appearance; perinuclear halo present; no nucleolus; N/C ratio is 60-80%
orthochromatophilic normoblast: 8-12 microns; round/ovoid cells with pink-orange uniformly staining cytoplasm, dark and opaque nucleus that may be pyknotic or in the process of being extruded, no nucleolus
reticulocyte: 7-10 microns; cannot identify without supravital stain (new methylene blue) that colors RNA deep blue and granular; must have at least 2 granules to classify as reticulocyte; cytoplasm is red to pale blue due to RNA, no nucleus is present; larger than mature erythrocyte and lacks central pallor
erythrocyte: 7-8 microns; round/ovoid biconcave disc with orange-red cytoplasm, no RNA, no nucleus
Diagram: erythropoiesis
Micro images: erythroblast island #1; #2; proerythroblast #1; #2; #3; #4; #5; proerythroblast is large cell at upper left of center; there are also basophilic, polychromatophilic and orthochromatic normoblasts; basophilic normoblast #1; #2; #3; #4; #5; basophilic and polychromatophilic normoblasts #1; #2; polychromatophilic normoblast #1; #2; #3; #4; orthochromatic normoblast #1; #2; #3; #4; #5; reticulocyte #1; #2; #3; #4; normal red blood cells and reticulocytes; various precursors #1; #2
Virtual slides: erythroid hyperplasia
Positive stains: red blood cells - GLUT1, CD35, CD36 (early precursors), CD38, CD41, CD43, CD44, CD47, CD49d (erythrocyte precursors only), CD58, CD71 (precursors through reticulocytes), CD75, CD105 (erythrocyte precursors only), CD108, CD111, CD139 (weak), CD147, CD233, CD235a, CD235b, CD235ab, CD236, CD236R, CD238, CD239, CD240 CE, CD240 D, CD240 DCE, CD241
Negative stains: red blood cells - CD9, CD10, CD15, CD24, CD37, CD42a, CD45, CD46, CD47R, CD49d, CD53, CD57, CD71, CD81, CD82, CD114, CD226
EM images: normal erythrocyte #1; #2; reticulocyte #1; #2; erythroblast and erythrocytes
References: Wikipedia (reticulocyte)
Hematogones are lymphoid progenitor cells
Often found in young children as normal finding, and may be most common lymphoid population in neonates (Biol Neonate 2004;86:247)
Also associated with childhood cytopenias, neoplasms, ITP (Egypt J Immunol 2005;12:9), and regenerative marrow after chemotherapy or bone marrow transplantation
May distort analysis of acute lymphoblastic leukemia in flow cytometry since markers are similar
Have been separated into three types (Neoplasma 2005;52:502)
Case reports: excessive hematogones in CMV+ neonate with immune thrombocytopenia (Leuk Res 2003;27:193), CD5+ hematogones in 5 year old girl with Shwachman-Diamond syndrome (Pediatr Dev Pathol 2001;4:505), sisters with Schwachman-Diamond syndrome who died as neonates (Archives 2000;124:1379)
Micro:
lymphoblast: resembles lymphoblasts in ALL; 10-20 microns (small/medium size), round/oval with sparse deeply basophilic cytoplasm without granules but may have vacuoles; indented nucleus with homogeneous fine, lacy and smudged chromatin; variable nucleoli
prolymphocyte: same size as lymphoblasts (10-20 microns) but more cytoplasm than lymphoblasts or mature lymphocytes, usually homogeneously blue cytoplasm; central round nucleus with single prominent nucleolus; coarser chromatin than lymphoblasts; N/C ratio is 75-85%
lymphocytes: 7-15 microns, round/ovoid but may have notches or indentations; variable light blue cytoplasm (often sparse); dense chromatin, usually no nucleolus; N/C ratio is 35-85%
Micro images: hematogones #1; #2; #3 (figures A, C, D); #4-post bone marrow transplant; hematogones-left vs. ALL-right; child with 3 large hematogone cells in upper left that have sparse, lightly basophilic cytoplasm; five month old with neuroblastoma and increased hematogones evenly distributed #1; #2-hematogones have clumped nuclear chromatin and no distinct nucleoli
Flow cytometry images: hematogones #1; #2
Positive stains: commonly CD10+, CD38 (bright), CD19+ by flow cytometry; heterogeneous expression of CD19, CD20, CD22, CD10, CD34, TdT; also CD38, CD43 (Br J Haematol 2005;128:820); more CD20+ cells than CD34/TdT+ cells (AJCP 2000;114:66)
Negative staining: surface immunoglobulin
DD: ALL (staining is homogeneous for various markers, not heterogeneous; deviates from normal B cell maturation spectrum with maturation arrest, aberrant expression of myeloid antigens and asynchronous expression of B cell precursors, Blood 2001;98:2498, Leuk Lymphoma 2004;45:277)
References: AJCP 1994;102:202 (adults)
Lymphocyte maturation in bone marrow
Lymphocyte precursors originate in bone marrow
B cells complete most of their development within the bone marrow, but T cells are generated in the thymus from precursor cells that migrate from the bone marrow
B cell development in marrow is dependent on CD10+ stromal cells (J Pathol 2005;205:311), which form specific adhesive contacts with developing B lineage cells, and also provide growth factors (stem cell factor, IL-7, stromal cell derived factor 1)
Earliest stem cells are in subendosteum, adjacent to inner bone surface; with maturation, B lineage cells move towards central axis of marrow; final stages of development of immature B cells occur in peripheral lymphoid organs (spleen, lymph nodes)
Micro: diffusely scattered throughout interstitium; 10% of marrow cells in adults; aggregates often present
Micro images: movement of B lineage cells with maturation
EM images: small lymphocyte #1; #2 with cytoplasmic projections
References: Immunobiology online textbook
Part of immune system
Similar to basophils, but generated by different CD34+ precursor cells in bone marrow
Mast cells leave bone marrow and circulate in immature form, and only mature at tissue site
Play a central role in allergic reactions through IgE receptor mediated responses
Stem cell factor is crucial for their development, proliferation and maturation (Immunol Res 2006;34:97)
Micro: rare in normal marrow; larger (up to 100%) than basophils with irregular elongated spindle shapes and cytoplasmic extensions; cytoplasm is packed with basophilic granules that may obscure nuclear margin; nucleus is round and single
Micro images: prominent basophilic granules #1; #2; #3; #4; #5; #6; #7; #8
Positive stains: Giemsa stain, Leder stain (chloroacetate esterase), methylene blue (granules stain purple), microphthalmia transcription factor, CD13 (immature and neoplastic mast cells), CD29, CD33, CD34, CD41, CD43, CD45, CD50, CD52, CD61, CD63, CD68, CD88 (J Allergy Clin Immunol 2005;115:1162), CD117, CD172a, CD203c
Negative stains: CD1-CD8, CD10-CD17, CD19-CD24, CD25 (non-neoplastic mast cells), CD38
References: Wikipedia, Blood 1989;73:1778
Megakaryocyte maturation in bone marrow
Progresses from myeloid stem cell to megakaryoblast to promegakaryocyte to megakaryocyte to proplatelets (released into circulation) to platelets (J Thromb Haemost 2003;1:1580, Front Biosci 2007;12:2050)
Maturation is characterized by an increase in size and lobulation of nuclei, and is controlled by thrombopoietin (J Clin Invest 2005;115:3339)
Megakaryocytes form demarcation membrane within cytosol, which leads to production of platelets
Diagrams: megakaryopoiesis pathways; proplatelet formation
Micro:
megakaryoblast: variable size (7-35 microns); may be designated micromegakaryoblasts if less than 15 microns; round/ovoid cells with scanty blue agranular cytoplasm that often forms a rim around nucleus and may have a few small budding protrusions at periphery; nuclei are round/oval with coarse granular chromatin, one or more nucleoli
megakaryocyte: randomly disbursed throughout bone marrow; 50-150 microns (largest normal nucleated cell in marrow); micromegakaryocytes measure 15-30 microns; abundant light blue to pink cytoplasm with numerous purple-red or pink granules; nucleus has 8, 16 or 32 overlapping lobes; no nucleolus; megakaryocytes producing platelets may have demarcated granular clumps of platelets streaming from the margins
Micro images: megakaryoblasts #1; #2; #3; #4; #5 with GPIIb/IIIa (CD42b) stain; megakaryoblast exhibiting emperipolesis #1; #2; megakaryoblast and megakaryocyte exhibiting emperipolesis; promegakaryocyte #1; #2; #3-various images; normal appearing megakaryocytes #1; #2; #3; #4; CD34+ megakaryocytes (figures A, C, D); CD62P+ megakaryocyte; megakaryocyte emperipolesis of erythrocytes; mildly increased megakaryopoiesis; proplatelet formation #1; #2; platelet formation #1; #2; #3
Positive stains: CD41, CD61; also CD9, CD31, CD34, CD36, CD42a, CD42b, CD42c, CD42d, CD43, CD49b, CD49f, CD51, CD62P, CD110, CD111, CD112, CD141, CD151, CD226 (Eur J Haematol 2005;74:228)
Negative stains: CD45, CD68
EM images: platelets; inactive platelet
References: J Clin Invest 2005;115:3348, J Clin Invest 2005;115:3332
Monocyte maturation in bone marrow
Progresses from myeloid stem cell to monoblast to promonocyte to monocyte (bone marrow) to monocyte (peripheral blood) to macrophage (in tissues)
Difficult to identify monoblasts and promonocytes in normal bone marrow
Contain granules similar to those in neutrophils, but fewer and smaller
Monocytes are also precursors of dendritic cells
Micro:
monoblast - 12-20 microns, moderate basophilic cytoplasm without granules, often intense staining on periphery and with perinuclear zone, round/oval nuclei with fine chromatin and 1-4 nucleoli; nucleus may show indentations or folding
promonocyte - features intermediate between monoblasts and monocytes
monocyte - largest of leukocytes (12-20 microns); round with smooth margins or pseudopod-like cytoplasmic extensions; abundant agranular light-blue cytoplasm with fine pink azurophilic granules; may have vacuoles or phagocytized material; large bilobed, kidney shaped or U shaped nucleus with moderately clumped chromatin; no nucleolus; N/C ratio is 65-80%;
Micro images: stem cell; monoblast #1; #2; #3; promonocyte #1; #2; #3; monocyte #1; #2; #3; #4; #5
bone marrow in acute monocytic leukemia (AML M4) - monoblasts are larger cells with abundant cytoplasm and round nuclei, and promonocytes are two cells with folded and creased nuclei next to monoblast in center
peripheral blood: monocyte #1; #2; #3
Positive stains: mainly CD14; also CD7, CD11a, CD11b, CD11c, CD11d, CD12, CD13, CD15 (variable), CD15u, CD17, CD18, CD23 (activated), CD29, CD30, CD32, CD33, CD36, CD37, CD38, CD39, CD40, CD43, CD44R, CD45, CD45RB, CD45RC, CD45RO, CD48, CD49a, CD49b, CD49d, CD49e, CD49f, CD51, CD52, CD54, CD61, CD62L, CD64, CD65, CD65s, CD68, CD83 (transient), CD84, CD85A, CD85B, CD85D, CD85E, CD85F, CD85I, CD85J, CD85K, CD85M, CD86, CD87, CD88, CD89, CD91, CD92, CD93, CD97, CD101, CD102, CD105 (activated), CD111, CD112, CD114, CD116, CD122, CD123 (plasmacytoid), CD126, CD127, CD128, CD132, CD137, CD139, CD141, CD148, CD156, CD157, CD163, CD165, CD166 (activated), CD171, CD180, CD210, CD226, CD227
Negative stains: CD24, CD56, CD57, CD60 (usually), CD231
EM images: monocyte #1; #2
Neutrophil maturation in bone marrow
Progresses from myeloid stem cell to myeloblast type I to myeloblast type II to promyelocyte to neutrophilic myelocyte to neutrophilic metamyelocyte to neutrophilic band to segmented neutrophil (polymorphonuclear neutrophil-PMN)
Maturation is characterized by decreasing N/C ratio and increasing granule production and nuclear segmentation
Immature forms are usually paratrabecular or perivascular; exceptions are after bone marrow transplantation, cytokine administration or chemotherapy
Primary granules: large, round, red-pink, electron dense; contain myeloperoxidase, elastase, lysozyme, cathepsin G, acid hydrolases; also called azurophilic (stains sky blue with azure stains used in the past); these granules are formed in promyelocytes (Blood 1979;53:179 , free full text)
Secondary (specific) granules: smaller, electron lucent (clear), cause characteristic cytoplasmic color in Wright stained preparations; contain lactoferrin and lysozyme; these granules are formed in myelocytes
Micro:
myeloblast: 15-20 microns, round/oval; usually scanty basophil cytoplasm with no perinuclear halo; may contain Auer rods (due to fusion of azurophilic granules) or delicate azurophilic granules; round/oval nuclei with occasional indentations or clefts; one or more nucleoli; finely reticulated chromatin; N/C ratio is 80-85%
type I myeloblast: no granules in cytoplasm
type II myeloblast: up to 15-20 delicate granules in cytoplasm
type III myeloblast: more than 15-20 cytoplasmic granules, but otherwise has features of a blast cell
promyelocyte: 10-20 microns; increased basophilic cytoplasm (compared to blasts) with primary coarse red-purple, azurophilic granules; large, round/oval nucleus with red-blue and fine to slightly condensed chromatin; 1-2 nucleoli; N/C ratio is 75-85%
myelocyte: 10-18 microns; round/oval with abundant pink cytoplasm with prominent red-purple azurophilic (primary) granules and numerous fine, lilac, specific (neutrophilic) secondary granules; round/oval to slightly indented nucleus with red-blue and slightly condensed chromatin; usually no nucleolus; N/C ratio is 50-65%
metamyelocyte: 10-16 microns; moderate pink or colorless cytoplasm with occasional red-purple azurophilic (primary) granules and variable fine, lilac, specific (neutrophilic) secondary granules; indented nucleus with light blue-purple and granular chromatin; no nucleolus; N/C ratio is 40-50%
band: 10-15 microns; abundant pink cytoplasm with many fine, lilac, neutrophilic (secondary) granules and possibly a few red-purple azurophilic (primary) granules; nucleus is indented to more than half the distance from the farthest nuclear margin; elongated and horseshoe-shaped nucleus; if lobulated, the bridge or isthmus between the lobes must be wide enough to have two distinct parallel dark margins with light nuclear chromatin between; has blue-purple and clumped granular chromatin; no nucleolus; N/C ratio is 33-40%
neutrophil: 10-15 microns; abundant pink cytoplasm with many fine, lilac, neutrophilic (specific or secondary) granules; lobulated (segmented) nucleus with 2-5 lobes, connected by a thin filament of chromatin; the filament is so narrow that there is no visible chromatin between the two sides; filaments may be difficult to visualize due to folding or twisting of nucleus; in other areas, the chromatin is dense with no nucleolus; N/C ratio is 33%
classify cell with folded nucleus as neutrophil if: (1) margins of two adjacent lobes are completely separated; (2) width of either of the two adjacent lobes markedly narrows or converges towards the junction of the lobes (making it possible for there to be a hidden filament), or (3) the nucleus is so extensively folded that one cannot determine if a filament is present
classify cell with folded nucleus as band if: (1) elongated band form crosses over itself without any evidence of constriction to a filament; (2) only the distal tip of the nucleus is slightly bent upon itself, and (3) the hidden area in the fold between two adjacent lobes is so small and the lobe width is so thick that it is unlikely that a thin filament is present
Micro images: type I myeloblast; type II myeloblast; type III myeloblast #1; #2; myeloblast (type not specified) #1; #2; #3; #4; #5; blast (upper) and promyelocyte (lower); myeloblast and normoblasts; early promyelocyte; late promyelocyte; various promyelocytes #1; #2; #3; #4; #5; #6 #7; #8 with band; myelocytes (three, from left to right), and 2 metamyelocytes (right and lower); myelocyte and bands; myelocyte and metamyelocyte; myelocyte #1; #2; metamyelocyte #1; #2; #3; #4; neutrophil myelocytes along endosteum of bone trabeculae #1; #2-myeloperoxidase stain; band #1; #2; #3; segmented neutrophil #1; #2; #3; perivascular immature granulocytes; paratrabecular myeloid precursors; primary (azurophilic) granules; few primary and many secondary granules
Positive stains: neutrophils (may also stain other precursors) - CD10, CD11b, CD11c, CD12, CD13, CD14 (weak-30%), CD15, CD15s, CD15u, CD16a, CD16b, CD17, CD18, CD24, CD29 (low), CD30, CD31, CD32, CD33 (low), CD35, CD37 (low), CD43, CD45RO, CD47, CD47R (weak), CD48 (weak), CD49e, CD62L, CD63 (weak), CD64, CD65s, CD66a, CD66b, CD66c, CD66d, CD66e, CD68, CD69, CD83, CD84, CD85F, CD85M, CD87, CD88, CD89, CD92, CD93, CD97, CD101, CD107a, CD107b (weak), CD114, CD116, CD128a, CD128b, CD132, CD139, CD141, CD148, CD156a, CD157, CD170
Negative stains: neutrophils - CD7, CD49d, CD52 (or weak), CD56, CD60, CD81, CD102, CD226
EM images: neutrophil #1; #2; #3; azurophilic granules; details of granules
References: CAP proficiency testing handbook, Blood Cells Mol Dis 2002;28:260 (antigenic changes during maturation)
Along endosteal surface of bony trabeculae or along margins in marrow smears
Common in children; in adults associated with various diseases and healing biopsy sites
Bone forming cell that arises from marrow mesenchymal cells
Synthesize angiopoietin and osteopontin, which inhibit hematopoietic stem cell proliferation (Br J Haematol 2006;134:467, J Clin Invest 2006;116:1195)