White Myeloid Cells: Histology

Overview

Definition

White myeloid cells are leukocytes developed from the common myeloid progenitor (CMP), which is derived from hematopoietic stem cells Hematopoietic stem cells Progenitor cells from which all blood cells derived. They are found primarily in the bone marrow and also in small numbers in the peripheral blood. Bone Marrow: Composition and Hematopoiesis (HSCs) of the bone marrow Bone marrow The soft tissue filling the cavities of bones. Bone marrow exists in two types, yellow and red. Yellow marrow is found in the large cavities of large bones and consists mostly of fat cells and a few primitive blood cells. Red marrow is a hematopoietic tissue and is the site of production of erythrocytes and granular leukocytes. Bone marrow is made up of a framework of connective tissue containing branching fibers with the frame being filled with marrow cells. Bone Marrow: Composition and Hematopoiesis.

• Not all leukocytes (WBCs) are derived from the myeloid progenitor.
• 2 major groups of leukocytes:
  • Granulocytes (derived from the myeloid progenitor):
    • Basophils Basophils Granular leukocytes characterized by a relatively pale-staining, lobate nucleus and cytoplasm containing coarse dark-staining granules of variable size and stainable by basic dyes. Innate Immunity: Phagocytes and Antigen Presentation
    • Eosinophils Eosinophils Granular leukocytes with a nucleus that usually has two lobes connected by a slender thread of chromatin, and cytoplasm containing coarse, round granules that are uniform in size and stainable by eosin. Innate Immunity: Phagocytes and Antigen Presentation
    • Neutrophils Neutrophils Granular leukocytes having a nucleus with three to five lobes connected by slender threads of chromatin, and cytoplasm containing fine inconspicuous granules and stainable by neutral dyes. Innate Immunity: Phagocytes and Antigen Presentation
    • Mast cells Mast cells Granulated cells that are found in almost all tissues, most abundantly in the skin and the gastrointestinal tract. Like the basophils, mast cells contain large amounts of histamine and heparin. Unlike basophils, mast cells normally remain in the tissues and do not circulate in the blood. Mast cells, derived from the bone marrow stem cells, are regulated by the stem cell factor. Innate Immunity: Phagocytes and Antigen Presentation
  • Agranulocytes (derived from myeloid and lymphoid progenitors):
    • Monocytes Monocytes Large, phagocytic mononuclear leukocytes produced in the vertebrate bone marrow and released into the blood; contain a large, oval or somewhat indented nucleus surrounded by voluminous cytoplasm and numerous organelles. Innate Immunity: Phagocytes and Antigen Presentation (myeloid)
    • Lymphocytes Lymphocytes Lymphocytes are heterogeneous WBCs involved in immune response. Lymphocytes develop from the bone marrow, starting from hematopoietic stem cells (HSCs) and progressing to common lymphoid progenitors (CLPs). B and T lymphocytes and natural killer (NK) cells arise from the lineage. Lymphocytes: Histology (lymphoid)

Cell description

Myelopoiesis

Myeloid cell production

• Hematopoiesis Hematopoiesis The development and formation of various types of blood cells. Hematopoiesis can take place in the bone marrow (medullary) or outside the bone marrow (extramedullary hematopoiesis). Bone Marrow: Composition and Hematopoiesis:
  • 1st to 2nd month in utero: mesoderm Mesoderm The middle germ layer of an embryo derived from three paired mesenchymal aggregates along the neural tube. Gastrulation and Neurulation of the yolk sac Yolk Sac The first of four extra-embryonic membranes to form during embryogenesis. In reptiles and birds, it arises from endoderm and mesoderm to incorporate the egg yolk into the digestive tract for nourishing the embryo. In placental mammals, its nutritional function is vestigial; however, it is the source of intestinal mucosa; blood cells; and germ cells. It is sometimes called the vitelline sac, which should not be confused with the vitelline membrane of the egg. Embryoblast and Trophoblast Development
  • By the 2nd month: moves to the liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver: Anatomy (and spleen Spleen The spleen is the largest lymphoid organ in the body, located in the LUQ of the abdomen, superior to the left kidney and posterior to the stomach at the level of the 9th-11th ribs just below the diaphragm. The spleen is highly vascular and acts as an important blood filter, cleansing the blood of pathogens and damaged erythrocytes. Spleen: Anatomy)
  • By the 5th month: occurs in the bone marrow Bone marrow The soft tissue filling the cavities of bones. Bone marrow exists in two types, yellow and red. Yellow marrow is found in the large cavities of large bones and consists mostly of fat cells and a few primitive blood cells. Red marrow is a hematopoietic tissue and is the site of production of erythrocytes and granular leukocytes. Bone marrow is made up of a framework of connective tissue containing branching fibers with the frame being filled with marrow cells. Bone Marrow: Composition and Hematopoiesis, which becomes the predominant source of blood cells
• Myelopoiesis starts with multipotent HSCs in the bone marrow Bone marrow The soft tissue filling the cavities of bones. Bone marrow exists in two types, yellow and red. Yellow marrow is found in the large cavities of large bones and consists mostly of fat cells and a few primitive blood cells. Red marrow is a hematopoietic tissue and is the site of production of erythrocytes and granular leukocytes. Bone marrow is made up of a framework of connective tissue containing branching fibers with the frame being filled with marrow cells. Bone Marrow: Composition and Hematopoiesis.
•  HSCs → multipotent progenitor ( MPP MPP Specialized stem cells that are committed to give rise to cells that have a particular function; examples are myoblasts; myeloid progenitor cells; and skin stem cells. Bone Marrow: Composition and Hematopoiesis) cells → CMP (which eventually differentiates into granulocytes, monocytes Monocytes Large, phagocytic mononuclear leukocytes produced in the vertebrate bone marrow and released into the blood; contain a large, oval or somewhat indented nucleus surrounded by voluminous cytoplasm and numerous organelles. Innate Immunity: Phagocytes and Antigen Presentation, platelets Platelets Platelets are small cell fragments involved in hemostasis. Thrombopoiesis takes place primarily in the bone marrow through a series of cell differentiation and is influenced by several cytokines. Platelets are formed after fragmentation of the megakaryocyte cytoplasm. Platelets: Histology, and erythrocytes Erythrocytes Erythrocytes, or red blood cells (RBCs), are the most abundant cells in the blood. While erythrocytes in the fetus are initially produced in the yolk sac then the liver, the bone marrow eventually becomes the main site of production. Erythrocytes: Histology)

Regulation

Development

Neutrophils Neutrophils Granular leukocytes having a nucleus with three to five lobes connected by slender threads of chromatin, and cytoplasm containing fine inconspicuous granules and stainable by neutral dyes. Innate Immunity: Phagocytes and Antigen Presentation, eosinophils Eosinophils Granular leukocytes with a nucleus that usually has two lobes connected by a slender thread of chromatin, and cytoplasm containing coarse, round granules that are uniform in size and stainable by eosin. Innate Immunity: Phagocytes and Antigen Presentation, basophils Basophils Granular leukocytes characterized by a relatively pale-staining, lobate nucleus and cytoplasm containing coarse dark-staining granules of variable size and stainable by basic dyes. Innate Immunity: Phagocytes and Antigen Presentation

• Neutrophils Neutrophils Granular leukocytes having a nucleus with three to five lobes connected by slender threads of chromatin, and cytoplasm containing fine inconspicuous granules and stainable by neutral dyes. Innate Immunity: Phagocytes and Antigen Presentation are derived from the colony-forming unit granulocyte-macrophage (CFU-GM).
• Eosinophils Eosinophils Granular leukocytes with a nucleus that usually has two lobes connected by a slender thread of chromatin, and cytoplasm containing coarse, round granules that are uniform in size and stainable by eosin. Innate Immunity: Phagocytes and Antigen Presentation (Eo) and basophils Basophils Granular leukocytes characterized by a relatively pale-staining, lobate nucleus and cytoplasm containing coarse dark-staining granules of variable size and stainable by basic dyes. Innate Immunity: Phagocytes and Antigen Presentation (Ba) come from progenitor-cell CFU-Eo and CFU-Ba, respectively.
• Subsequent stages:
  1. Myeloblast: 
     • 1st granulocytic precursor
     • Cytoplasm with no granules
     • Large nucleus Nucleus Within a eukaryotic cell, a membrane-limited body which contains chromosomes and one or more nucleoli (cell nucleolus). The nuclear membrane consists of a double unit-type membrane which is perforated by a number of pores; the outermost membrane is continuous with the endoplasmic reticulum. A cell may contain more than one nucleus. The Cell: Organelles and faint nucleoli
  2. Promyelocyte:
     • Azurophilic granules Azurophilic granules Myeloperoxidase Deficiency form.
     • The granules contain lysosomal hydrolases Hydrolases Any member of the class of enzymes that catalyze the cleavage of the substrate and the addition of water to the resulting molecules, e.g., esterases, glycosidases (glycoside hydrolases), lipases, nucleotidases, peptidases (peptide hydrolases), and phosphatases (phosphoric monoester hydrolases). Basics of Enzymes and myeloperoxidase Myeloperoxidase Acute Myeloid Leukemia.
  3. Myelocyte: 
     • 1st sign of differentiation: Specific granules develop for the particular cell type.
     • Different sets of genes Genes A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms. DNA Types and Structure are activated; lineages for the 3 types of granulocytes form.
     • Cell division Cell Division A type of cell nucleus division by means of which the two daughter nuclei normally receive identical complements of the number of chromosomes of the somatic cells of the species. Cell Cycle ceases.
  4. Metamyelocyte:
     • Granules are dispersed.
     • Nuclear indentation and lobulation occur.
     • Neutrophilic, basophilic, and eosinophilic metamyelocytes undergo further condensation of their nuclei.
• Differentiation:
  • Neutrophils Neutrophils Granular leukocytes having a nucleus with three to five lobes connected by slender threads of chromatin, and cytoplasm containing fine inconspicuous granules and stainable by neutral dyes. Innate Immunity: Phagocytes and Antigen Presentation:
    • From the neutrophilic-metamyelocyte stage, neutrophils Neutrophils Granular leukocytes having a nucleus with three to five lobes connected by slender threads of chromatin, and cytoplasm containing fine inconspicuous granules and stainable by neutral dyes. Innate Immunity: Phagocytes and Antigen Presentation become band neutrophils Neutrophils Granular leukocytes having a nucleus with three to five lobes connected by slender threads of chromatin, and cytoplasm containing fine inconspicuous granules and stainable by neutral dyes. Innate Immunity: Phagocytes and Antigen Presentation or stab cells (intermediate stage with an elongated, not polymorphic, nucleus Nucleus Within a eukaryotic cell, a membrane-limited body which contains chromosomes and one or more nucleoli (cell nucleolus). The nuclear membrane consists of a double unit-type membrane which is perforated by a number of pores; the outermost membrane is continuous with the endoplasmic reticulum. A cell may contain more than one nucleus. The Cell: Organelles)
    • Segmented neutrophil: nearly mature
    • Mature neutrophil: exits to the peripheral blood
  • Eosinophils Eosinophils Granular leukocytes with a nucleus that usually has two lobes connected by a slender thread of chromatin, and cytoplasm containing coarse, round granules that are uniform in size and stainable by eosin. Innate Immunity: Phagocytes and Antigen Presentation: from eosinophilic metamyelocyte → mature eosinophil
  • Basophils Basophils Granular leukocytes characterized by a relatively pale-staining, lobate nucleus and cytoplasm containing coarse dark-staining granules of variable size and stainable by basic dyes. Innate Immunity: Phagocytes and Antigen Presentation: from basophilic metamyelocyte → mature basophil

Monocytes Monocytes Large, phagocytic mononuclear leukocytes produced in the vertebrate bone marrow and released into the blood; contain a large, oval or somewhat indented nucleus surrounded by voluminous cytoplasm and numerous organelles. Innate Immunity: Phagocytes and Antigen Presentation

• Derived from the CFU-GM (similar to neutrophils Neutrophils Granular leukocytes having a nucleus with three to five lobes connected by slender threads of chromatin, and cytoplasm containing fine inconspicuous granules and stainable by neutral dyes. Innate Immunity: Phagocytes and Antigen Presentation)
• Stages:
  • Monoblast:
    • 1st monocyte precursor
    • Round nucleus Nucleus Within a eukaryotic cell, a membrane-limited body which contains chromosomes and one or more nucleoli (cell nucleolus). The nuclear membrane consists of a double unit-type membrane which is perforated by a number of pores; the outermost membrane is continuous with the endoplasmic reticulum. A cell may contain more than one nucleus. The Cell: Organelles
  • Promonocyte:
    • Convoluted, indented nucleus Nucleus Within a eukaryotic cell, a membrane-limited body which contains chromosomes and one or more nucleoli (cell nucleolus). The nuclear membrane consists of a double unit-type membrane which is perforated by a number of pores; the outermost membrane is continuous with the endoplasmic reticulum. A cell may contain more than one nucleus. The Cell: Organelles
    • Variable Variable Variables represent information about something that can change. The design of the measurement scales, or of the methods for obtaining information, will determine the data gathered and the characteristics of that data. As a result, a variable can be qualitative or quantitative, and may be further classified into subgroups. Types of Variables basophilic granules
  • Monocyte:
    • Lobulated, indented nucleus Nucleus Within a eukaryotic cell, a membrane-limited body which contains chromosomes and one or more nucleoli (cell nucleolus). The nuclear membrane consists of a double unit-type membrane which is perforated by a number of pores; the outermost membrane is continuous with the endoplasmic reticulum. A cell may contain more than one nucleus. The Cell: Organelles
    • Occasional or no granules
    • Once recruited into tissues, the cell differentiates into macrophages Macrophages The relatively long-lived phagocytic cell of mammalian tissues that are derived from blood monocytes. Main types are peritoneal macrophages; alveolar macrophages; histiocytes; kupffer cells of the liver; and osteoclasts. They may further differentiate within chronic inflammatory lesions to epithelioid cells or may fuse to form foreign body giant cells or langhans giant cells. Innate Immunity: Phagocytes and Antigen Presentation.

Mast cells Mast cells Granulated cells that are found in almost all tissues, most abundantly in the skin and the gastrointestinal tract. Like the basophils, mast cells contain large amounts of histamine and heparin. Unlike basophils, mast cells normally remain in the tissues and do not circulate in the blood. Mast cells, derived from the bone marrow stem cells, are regulated by the stem cell factor. Innate Immunity: Phagocytes and Antigen Presentation

• Mast cells Mast cells Granulated cells that are found in almost all tissues, most abundantly in the skin and the gastrointestinal tract. Like the basophils, mast cells contain large amounts of histamine and heparin. Unlike basophils, mast cells normally remain in the tissues and do not circulate in the blood. Mast cells, derived from the bone marrow stem cells, are regulated by the stem cell factor. Innate Immunity: Phagocytes and Antigen Presentation arise from the bone marrow Bone marrow The soft tissue filling the cavities of bones. Bone marrow exists in two types, yellow and red. Yellow marrow is found in the large cavities of large bones and consists mostly of fat cells and a few primitive blood cells. Red marrow is a hematopoietic tissue and is the site of production of erythrocytes and granular leukocytes. Bone marrow is made up of a framework of connective tissue containing branching fibers with the frame being filled with marrow cells. Bone Marrow: Composition and Hematopoiesis: HSCs → CMP → CFU-GM → mast cell Mast cell Granulated cells that are found in almost all tissues, most abundantly in the skin and the gastrointestinal tract. Like the basophils, mast cells contain large amounts of histamine and heparin. Unlike basophils, mast cells normally remain in the tissues and do not circulate in the blood. Mast cells, derived from the bone marrow stem cells, are regulated by the stem cell factor. Angioedema progenitor
• Unlike other HSC-derived cells, mast cell Mast cell Granulated cells that are found in almost all tissues, most abundantly in the skin and the gastrointestinal tract. Like the basophils, mast cells contain large amounts of histamine and heparin. Unlike basophils, mast cells normally remain in the tissues and do not circulate in the blood. Mast cells, derived from the bone marrow stem cells, are regulated by the stem cell factor. Angioedema progenitors (immature form) are released into the blood.
• Mast cell Mast cell Granulated cells that are found in almost all tissues, most abundantly in the skin and the gastrointestinal tract. Like the basophils, mast cells contain large amounts of histamine and heparin. Unlike basophils, mast cells normally remain in the tissues and do not circulate in the blood. Mast cells, derived from the bone marrow stem cells, are regulated by the stem cell factor. Angioedema progenitors are recruited to mucosal and epithelial tissues, undergo terminal differentiation, and become mature mast cells Mast cells Granulated cells that are found in almost all tissues, most abundantly in the skin and the gastrointestinal tract. Like the basophils, mast cells contain large amounts of histamine and heparin. Unlike basophils, mast cells normally remain in the tissues and do not circulate in the blood. Mast cells, derived from the bone marrow stem cells, are regulated by the stem cell factor. Innate Immunity: Phagocytes and Antigen Presentation.

Clinical Relevance

• Acute myeloid leukemia Acute Myeloid Leukemia Acute myeloid leukemia (AML) is a hematologic malignancy characterized by the uncontrolled proliferation of myeloid precursor cells. Seen predominantly in older adults, AML includes an accumulation of myeloblasts and a replacement of normal marrow by malignant cells, which leads to impaired hematopoiesis. Acute Myeloid Leukemia ( AML AML Acute myeloid leukemia (AML) is a hematologic malignancy characterized by the uncontrolled proliferation of myeloid precursor cells. Seen predominantly in older adults, AML includes an accumulation of myeloblasts and a replacement of normal marrow by malignant cells, which leads to impaired hematopoiesis. Acute Myeloid Leukemia): characterized by uncontrolled proliferation of myeloid precursor cells. Acute myeloid leukemia Acute Myeloid Leukemia Acute myeloid leukemia (AML) is a hematologic malignancy characterized by the uncontrolled proliferation of myeloid precursor cells. Seen predominantly in older adults, AML includes an accumulation of myeloblasts and a replacement of normal marrow by malignant cells, which leads to impaired hematopoiesis. Acute Myeloid Leukemia includes an accumulation of myeloblasts. Normal marrow is replaced by malignant cells, which leads to impaired hematopoiesis Hematopoiesis The development and formation of various types of blood cells. Hematopoiesis can take place in the bone marrow (medullary) or outside the bone marrow (extramedullary hematopoiesis). Bone Marrow: Composition and Hematopoiesis. A clinical presentation consisting of fatigue Fatigue The state of weariness following a period of exertion, mental or physical, characterized by a decreased capacity for work and reduced efficiency to respond to stimuli. Fibromyalgia, bleeding, fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever, and infection is related to anemia Anemia Anemia is a condition in which individuals have low Hb levels, which can arise from various causes. Anemia is accompanied by a reduced number of RBCs and may manifest with fatigue, shortness of breath, pallor, and weakness. Subtypes are classified by the size of RBCs, chronicity, and etiology. Anemia: Overview and Types, thrombocytopenia Thrombocytopenia Thrombocytopenia occurs when the platelet count is < 150,000 per microliter. The normal range for platelets is usually 150,000-450,000/µL of whole blood. Thrombocytopenia can be a result of decreased production, increased destruction, or splenic sequestration of platelets. Patients are often asymptomatic until platelet counts are < 50,000/µL. Thrombocytopenia, and lack of functional WBCs. Diagnosis is via peripheral blood smear Peripheral Blood Smear Anemia: Overview and Types and bone marrow Bone marrow The soft tissue filling the cavities of bones. Bone marrow exists in two types, yellow and red. Yellow marrow is found in the large cavities of large bones and consists mostly of fat cells and a few primitive blood cells. Red marrow is a hematopoietic tissue and is the site of production of erythrocytes and granular leukocytes. Bone marrow is made up of a framework of connective tissue containing branching fibers with the frame being filled with marrow cells. Bone Marrow: Composition and Hematopoiesis biopsy Biopsy Removal and pathologic examination of specimens from the living body. Ewing Sarcoma showing myeloblasts. The precursor cells contain Auer rods Auer Rods Acute Myeloid Leukemia. 
• Chronic myeloid leukemia Chronic myeloid leukemia Chronic myeloid leukemia is a malignant proliferation of the granulocytic cell line characterized by a fairly normal differentiation. The underlying genetic abnormality is the Philadelphia chromosome, an abbreviated chromosome 22, resulting from reciprocal (9;22)(q34;q11) translocation. Chronic Myeloid Leukemia ( CML CML Chronic myeloid leukemia is a malignant proliferation of the granulocytic cell line characterized by a fairly normal differentiation. The underlying genetic abnormality is the Philadelphia chromosome, an abbreviated chromosome 22, resulting from reciprocal (9;22)(q34;q11) translocation. Chronic Myeloid Leukemia): malignant proliferation of the granulocytic cell line, with a fairly normal differentiation. The underlying genetic abnormality is the Philadelphia chromosome Philadelphia chromosome An aberrant form of human chromosome 22 characterized by translocation of the distal end of chromosome 9 from 9q34, to the long arm of chromosome 22 at 22q11. It is present in the bone marrow cells of 80 to 90 percent of patients with chronic myelocytic leukemia. Acute Lymphoblastic Leukemia, an abbreviated chromosome Chromosome In a prokaryotic cell or in the nucleus of a eukaryotic cell, a structure consisting of or containing DNA which carries the genetic information essential to the cell. Basic Terms of Genetics 22 resulting from reciprocal (9;22)(q34;q11) translocation. Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship can be asymptomatic, or have sternal pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways and splenomegaly Splenomegaly Splenomegaly is pathologic enlargement of the spleen that is attributable to numerous causes, including infections, hemoglobinopathies, infiltrative processes, and outflow obstruction of the portal vein. Splenomegaly. Laboratory studies show elevated WBC with increased immature cells. Philadelphia chromosome Philadelphia chromosome An aberrant form of human chromosome 22 characterized by translocation of the distal end of chromosome 9 from 9q34, to the long arm of chromosome 22 at 22q11. It is present in the bone marrow cells of 80 to 90 percent of patients with chronic myelocytic leukemia. Acute Lymphoblastic Leukemia demonstration by cytogenetic techniques is considered the gold standard of diagnostic testing. 
• Chronic eosinophilic leukemia Chronic eosinophilic leukemia Chronic eosinophilic leukemia (CEL) is a chronic myeloproliferative neoplasm caused by autonomous clonal proliferation of normal-appearing eosinophils, resulting in increased eosinophils in the peripheral blood and bone marrow. The disorder is a myeloid variant of hypereosinophilic syndrome (HES) and is associated with tissue infiltration leading to end-organ damage. Chronic Eosinophilic Leukemia ( CEL CEL Chronic eosinophilic leukemia (CEL) is a chronic myeloproliferative neoplasm caused by autonomous clonal proliferation of normal-appearing eosinophils, resulting in increased eosinophils in the peripheral blood and bone marrow. The disorder is a myeloid variant of hypereosinophilic syndrome (HES) and is associated with tissue infiltration leading to end-organ damage. Chronic Eosinophilic Leukemia): a chronic myeloproliferative neoplasm caused by autonomous clonal proliferation of normal-appearing eosinophils Eosinophils Granular leukocytes with a nucleus that usually has two lobes connected by a slender thread of chromatin, and cytoplasm containing coarse, round granules that are uniform in size and stainable by eosin. Innate Immunity: Phagocytes and Antigen Presentation, resulting in elevated eosinophils Eosinophils Granular leukocytes with a nucleus that usually has two lobes connected by a slender thread of chromatin, and cytoplasm containing coarse, round granules that are uniform in size and stainable by eosin. Innate Immunity: Phagocytes and Antigen Presentation in the peripheral blood and bone marrow Bone marrow The soft tissue filling the cavities of bones. Bone marrow exists in two types, yellow and red. Yellow marrow is found in the large cavities of large bones and consists mostly of fat cells and a few primitive blood cells. Red marrow is a hematopoietic tissue and is the site of production of erythrocytes and granular leukocytes. Bone marrow is made up of a framework of connective tissue containing branching fibers with the frame being filled with marrow cells. Bone Marrow: Composition and Hematopoiesis. The disorder is a myeloid variant of hypereosinophilic syndrome Hypereosinophilic syndrome A heterogeneous group of disorders with the common feature of prolonged eosinophilia of unknown cause and associated organ system dysfunction, including the heart, central nervous system, kidneys, lungs, gastrointestinal tract, and skin. There is a massive increase in the number of eosinophils in the blood, mimicking leukemia, and extensive eosinophilic infiltration of the various organs. Chronic Eosinophilic Leukemia ( HES HES A heterogeneous group of disorders with the common feature of prolonged eosinophilia of unknown cause and associated organ system dysfunction, including the heart, central nervous system, kidneys, lungs, gastrointestinal tract, and skin. There is a massive increase in the number of eosinophils in the blood, mimicking leukemia, and extensive eosinophilic infiltration of the various organs. Chronic Eosinophilic Leukemia) and associated with tissue infiltration, which leads to end-organ damage. Studies show an absolute eosinophilic count of ≥ 1.5 x 10⁹/L and bone marrow Bone marrow The soft tissue filling the cavities of bones. Bone marrow exists in two types, yellow and red. Yellow marrow is found in the large cavities of large bones and consists mostly of fat cells and a few primitive blood cells. Red marrow is a hematopoietic tissue and is the site of production of erythrocytes and granular leukocytes. Bone marrow is made up of a framework of connective tissue containing branching fibers with the frame being filled with marrow cells. Bone Marrow: Composition and Hematopoiesis blasts Blasts Injuries resulting when a person is struck by particles impelled with violent force from an explosion. Blast causes pulmonary contusion and hemorrhage, laceration of other thoracic and abdominal viscera, ruptured ear drums, and minor effects in the central nervous system. Blunt Chest Trauma of 5%–19%. Evidence of clonal abnormality or elevated blasts Blasts Injuries resulting when a person is struck by particles impelled with violent force from an explosion. Blast causes pulmonary contusion and hemorrhage, laceration of other thoracic and abdominal viscera, ruptured ear drums, and minor effects in the central nervous system. Blunt Chest Trauma is needed for diagnosis. Without either, idiopathic Idiopathic Dermatomyositis HES HES A heterogeneous group of disorders with the common feature of prolonged eosinophilia of unknown cause and associated organ system dysfunction, including the heart, central nervous system, kidneys, lungs, gastrointestinal tract, and skin. There is a massive increase in the number of eosinophils in the blood, mimicking leukemia, and extensive eosinophilic infiltration of the various organs. Chronic Eosinophilic Leukemia is the appropriate term. 
• Mastocytosis: a group of disorders with excessive accumulation of mast cells Mast cells Granulated cells that are found in almost all tissues, most abundantly in the skin and the gastrointestinal tract. Like the basophils, mast cells contain large amounts of histamine and heparin. Unlike basophils, mast cells normally remain in the tissues and do not circulate in the blood. Mast cells, derived from the bone marrow stem cells, are regulated by the stem cell factor. Innate Immunity: Phagocytes and Antigen Presentation in the tissue. Cutaneous mastocytosis is limited to the skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions. Systemic mastocytosis infiltrates multiple organs outside the skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions. KIT mutations are a major contributing factor. Symptoms include flushing, pruritus Pruritus An intense itching sensation that produces the urge to rub or scratch the skin to obtain relief. Atopic Dermatitis (Eczema), and chronic allergic reactions Allergic Reactions Type I hypersensitivity reaction against plasma proteins in donor blood Transfusion Reactions.