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White cell disorders

White cell disorders. Disorders of white cells include deficiencies ( leukopenias ) and proliferations ( leukocytosis ), which may be reactive or neoplastic . Reactive proliferation most often microbial disease

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White cell disorders

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  1. White cell disorders • Disorders of white cells include deficiencies (leukopenias) and proliferations (leukocytosis), which may be reactive or neoplastic. • Reactive proliferation most often microbial disease • Neoplastic disorders, though less common, are more ominous: They cause approximately 9% of all cancer deaths in adults and a staggering 40% in children younger than 15 years of age

  2. NON-NEOPLASTIC DISORDERS OF WHITE CELLS • Leukopenia: • results most commonly from a decrease in granulocytes, the most numerous circulating white cells. • Lymphopenia is much less common; it is associated with rare congenital immunodeficiency diseases, advanced HIV infection, and corticosteroids • Neutropenia/Agranulocytosis : A reduction in the number of granulocytes in blood; when severe = agranulocytosis. • Neutropenicpersons are susceptible to bacterial and fungal infections, in whom they can be fatal. • The risk of infection rises sharply as the neutrophil count falls below 500 cells/μL

  3. PATHOGENESIS of Neutropenia • Decreased granulocyte production. most often causes are: 1- marrow failure (e.g. aplastic anemia), extensive replacement of the marrow by tumor or cancer chemotherapy. 2- certain drugs 3- neoplastic proliferations of cytotoxic T cells • Increased granulocyte destruction. 1- immune-mediated injury (e.g. drugs, autoimmune disease) 2- overwhelming bacterial, fungal, or rickettsial infections due to increased peripheral utilization. 3- Splenomegaly (sequestration and accelerated removal of neutrophils).

  4. Clinical Features of Neutropenia • malaise, chills, and fever, marked weakness and fatigability. • Infections: constitute the major problem (ulcerating, necrotizing lesions of the gingiva, floor of the mouth, buccal mucosa, pharynx, or other sites within the oral cavity (agranulocytic angina)). • Treatment: 1) removal of the offending cause; e.g. drug 2)control of infection 3)granulocyte colony-stimulating factor, which stimulates neutrophil production by the bone marrow.

  5. Reactive Leukocytosis • An increase in the number of white cells in the blood • common in inflammatory states (microbial and nonmicrobial ). • Leukocytoses are classified according to the particular white cell series that is affected • in some cases reactive leukocytosis may mimic leukemia. Such "leukemoid" reactions” must be distinguished from true white cell malignancies.

  6. Reactive Lymphadenitis • Causes: - Infections - nonmicrobial inflammatory stimuli. • foreign antigens • can lead to lymph node enlargement (lymphadenopathy).

  7. NEOPLASMS OF WHITE CELLS • 1- Lymphoid neoplasms: include non-Hodgkin lymphomas (NHLs), Hodgkin lymphomas, lymphocytic leukemias, and plasma cell neoplasms. • 2- Myeloid neoplasms: arise from progenitor cells that give rise to granulocytes, red cells, and platelets. • 3- Histiocyticneoplasms : include proliferative lesions of macrophages and dendritic cells.

  8. The myeloid neoplasms • fall into three distinct subcategories: • acute myeloid leukemias (AML):immature progenitor cells accumulate in the bone marrow > 20% of bone marrow cellular component. • myeloproliferativedisorders: in which an inappropriate increase in the production of formed blood elements leads to elevated blood cell counts. All can transform to acute leukemia and to a depleted phase of marrow fibrosis associated with anemia, thrombocytopenia, and splenomegaly • myelodysplasticsyndromes: Poorly understood myeloid tumors characterized by disordered andineffective hematopoiesis and cytopenias. Transformation to AML occurs in 10% to 40%.

  9. MORPHOLOGY - AML • By definition, in AML myeloid blasts > 20% of bone marrow cellular component. • Myeloblasts(precursors of granulocytes) have delicate nuclear chromatin, three to five nucleoli, and fine azurophiliccytoplasmic granules • Auer rods: distinctive red-staining rodlike structures, may be present in myeloblasts, are specific for neoplasticmyeloblasts and thus a helpful diagnostic clue when present. • In other subtypes of AML, monoblasts, erythroblasts, or megakaryoblasts predominate

  10. Clinical Features of Acute Leukemias • Clinical signs and symptoms related to suppressed marrow function: fatigue (due to anemia), fever (reflecting infections resulting from neutropenia), and bleeding (petechiae, ecchymoses, epistaxis, gum bleeding) secondary to thrombocytopenia • Bone pain and tenderness, resulting from marrow expansion and infiltration of the subperiosteum • Generalized lymphadenopathy, splenomegaly, and hepatomegalydue to dissemination of the leukemic cells. • Central nervous system manifestations,including headache, vomiting, and nerve palsies resulting from meningeal spread.

  11. Laboratory Findings in Acute Leukemias • The diagnosis of acute leukemia rests on the identification of blasts in the peripheral blood and bone marrow. • The white cell count is variable; it may be greater than 100,000 cells/μL but in about half of the patients is less than 10,000 cells/μL. • Anemia is almost always present • platelet count usually is below 100,000/μL. • Neutropenia.

  12. Lymphoid Neoplasms • Classification is based on cell of origin and stage of differentiation. • Most common types in children are acute lymphoblastic leukemias/lymphoblastic lymphomas (ALL) derived from precursor B and T cells. • These highly aggressive tumors manifest with signs and symptoms of bone marrow failure, or as rapidly growing masses. • Tumor cells contain genetic lesions that block differentiation, leading to the accumulation of immature, nonfunctional blasts. • Most common types in adults are non-Hodgkin lymphomas derived from germinal center B cells

  13. THROMBOCYTOPENIA • = A count less than 150,000 platelets/μL • an increased risk of post-traumatic bleedingonlywhen platelet counts fall to 20,000 to 50,000 platelets/μL • spontaneous bleeding  below 20,000 platelets/μL. • Most bleeding occurs from small, superficial blood vessels and produces petechiae or large ecchymoses in the skin, the mucous membranes of the gastrointestinal and urinary tracts, and other sites. • Larger hemorrhages into the central nervous system are a major hazard in those with markedly depressed platelet counts

  14. Causes: • Decreased Production of Platelets • Generalized Bone Marrow Dysfunction • AplasticanemiaMarrow infiltration: leukemia, cancer • Drug-induced: alcohol, thiazides, cytotoxic drugs • Infections: measles, HIV • Megaloblastic anemia • Decreased Platelet Survival • Immunologic Destruction • Autoimmune

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