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APLASTIC ANEMIA. Dr. Bhavesh S. Jarwani. APLASTIC ANAEMIA Empty Marrow Syndrome. Is a disorder characterized by marked reduction or absence of erythroid, granulocytic and megakaryocytic cells in the marrow with resultant pancytopenia and reduced number of CD34+ and colony forming cells.

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Aplastic anemia

APLASTIC ANEMIA

Dr. Bhavesh S. Jarwani


Aplastic anaemia empty marrow syndrome
APLASTIC ANAEMIAEmpty Marrow Syndrome

Is a disorder characterized by marked reduction or absence of erythroid, granulocytic and megakaryocytic cells in the marrow with resultant pancytopenia and reduced number of CD34+ and colony forming cells.


Hematopoitic cell destruction by Immune Mechanisms in Acquired Aplastic Anemia.

There is normal stromal cells but decreased number of colony forming cells and stem cells as

it can be seen in Ps, radiographically, and also the stem cells number


Immune mechanics in aplastic anemia
Immune Mechanics in Aplastic Anemia Acquired Aplastic Anemia.

  • T cells:mononuclear cells from the ps or marrow suppressed the csf by the progenitor cells have elevated numbers of the cytotoxic T Lymphocytes

  • Cytokines:peripheral blood from this patients had raised levels of the soluble cytokines as y-INF and TNF and also y-INF mRNA , evidence of the gene expression


  • Incidence: Acquired Aplastic Anemia.5-10 cases per million persons per year

  • Age: Bimodal distribution

    • young adults (15-30 years)

    • elderly (above 60 years)

  • Same incidence in Male and Female

  • Geographic distribution

    • more common in Asia than in North America and Europe


Etiology
Etiology Acquired Aplastic Anemia.

  • Acquired:

    • Drugs: Antimetabolites, antimitotic agents, gold, chloramphenicol, phenylbutazone and sulfonamides

    • Radiation

    • Chemicals: benzenes, Solvents, insecticides

    • Viruses : Hepatitis A,B,C, E, G, and Parvo B19, CMV

    • PNH

    • Misc: pregnancy, connective tissue disorders, Graft-vs-Host disease

  • Hereditary:

    • Fanconi’s Anemia

    • Dyskeratosis congenita

    • Shwachman Syndrome

  • Idiopathic:

    • 50-65 % of cases


Etiology1
Etiology Acquired Aplastic Anemia.

  • Drugs may be having direct dose dependent toxicity to the marrow or having Idiosyncrasy to the drugs:

    • Antineoplastic and antimetabolites are having direct dose dependent toxicity

    • Chloramphenicol having first immediate dose dependent toxicity and long term Idiosyncrasy after one to two weeks later

  • Radiation:

    • Chronic exposure to low-dose and localized exposure leading to development of aplastic anemia

  • Benzene and insecticides:

    • direct and also induction of the hapten leading to immune mediated bone marrow suppression

  • Virus:

    • Hepatitis A,B,C,E and G. Parvovirus B19, CMV

  • Pregnancy:


Etiology2
Etiology Acquired Aplastic Anemia.

  • PNH:

    • defect in PIG-A gene, so partial or complete inability to construct Glycosylphosphatidylinositol(GPI) anchor for the attachment of CD55, CD59

    • diagnosis: Ham’s test, Flow cytometry using antibodies against cell surface antigens CD55, CD59 which are lacking in disease

  • Congenital disorders:

    • Fanconis Anemia

    • Shwachaman syndrome

    • Dyskeratosis congenita


Pathogenesis
Pathogenesis: Acquired Aplastic Anemia.

  • Having stem cell defect: how?

  • Having immune mechanism in this disease progress

  • Evidence:

  • immunosupresion better results in BMT,

  • Better treatment with Antithymocyte globulin and also immuno-suppression having comparable results to BMT

  • Activated T cells: overproduction of the cytokines as interferon y and TNFb that in turn leading to hematopoietic progenitors


How the destruction occurs
How the destruction occurs: Acquired Aplastic Anemia.

  • induction of the killing through programmed cell death.

  • Progenitor cells have Fas receptor , triggering that though the cytokines induces the apoptosis.

  • Also induces the production of the nitric oxide by marrow cells that in turn leads to the cell destruction

  • transcription regulator is required, I.e. IRF, interferon regulatory factor-1, and this is required for the negative action of the INF-y.


Antigens enciting aplastic anemia
ANTIGENS ENCITING APLASTIC ANEMIA: Acquired Aplastic Anemia.

  • Either endogenous or exogenous:

    • exogenous: hepatitis, drugs

    • endogenous: somatic mutation in the HSC leading to autoimmunity and at last the marrow failure immune response to peptides derived from the aberrantly processed proteins like GPI

  • Determinants of the autoimmunity:

    • HLA class I and II are associated with many human autoimmune diseases, HLA-DR2 is over expressed in American and Europe.

    • specific class 2 haplotypes in Japanese that are respondent to the CSA

  • Drugs:

    • genetically defined metabolic detoxification pathway in aplastic anemia


Presentation of Anemia, Neutropenia and Thrombocytopenia Acquired Aplastic Anemia.

Hemorrhagic lesion of the gums in a patient with aplastic anemia caused by infection with Capnocytophaga ochraceus; such lesions are easily confused with those of herpes simplex.


26- Acquired Aplastic Anemia.year-old woman with acute aplastic anemia and 1 day of facial pain/swelling. Mouth open involuntarily due to perioral edema. Needle aspirate of small purplish area near right alar revealed P aeruginosa.


Diagnosis and differential diagnosis
Diagnosis and differential Diagnosis Acquired Aplastic Anemia.

  • Peripheral Smearnormocytic, and normochronic with low reticulocyte count index <2% .i.e. hypoproliferative marrow

  • Bone Marrowmarrow spicules with empty fat cells and very few hematopoietic cells. Presence of dysplasia suggest MDs, so as karyotype anomaly suggest MDS.

  • Other tests:LDH, haptoglobulin, hams test, flow cytometry to know about PNH and also for fancony’s anemiahairy cell Leukemia: cytochemical I.e. tartrate-resistent acid phosphatase, and phenotypic, I.e. CD25+ monoclonal B cells

  • Classification:Severe: when nautrophic <500, platelets <20,000/microL, and reticulocyte <20,000/microL

  • Supersevere: when neutrophic count<200/microL


  • Course and prognosis of the disease: Acquired Aplastic Anemia.

    • with transfusion support alone: 80 % of cases succumb to death in 18 to 24 months, related to PMN count

    • with MBT and Immunosuppresion: curative in 60 to 90 % of cases, risk of CGVH threat

  • Supportive care:

    • transfusion of the blood products, CMV seronegative should be given transfusion from the family members should be avoided to prevent sensitization.

    • pooled donor platelets but leads to sensitization

    • in refractory cases need HLA matched transfusion

    • packed cells filtrated to remove leukocyte and platelets

    • iron overload : give chelating therapy deferoxamine

    • CMV prophylaxis

    • Staph. Aeureus * hospitalization * menses


  • Treatment modalities: Acquired Aplastic Anemia.

    • ATG: purified monomeric IgG from hyperimuune horse with human thymocyte and thoracis duct lymphocytes

    • 50 - 70 % good response

    • 20-30 complete and durable recovery

    • 70-80 have partial response

  • Complication:

    • MDS 30-6- %

    • also secondary solid tumors

    • response after 8 to 12 weeks

  • Other drugs to suppress immunity:

    • cyclosporine and cyclophosphamide and also high dose steroid

  • Growth factors:

    • Erythropoeitin, CG-CSF, GM-CSF, ILs 1,3, 6


  • Response is slow Acquired Aplastic Anemia.

  • Response is often incomplete

  • Response may require successive course of immunosuppression

  • Relapse is common and require maintenance therapy

  • Evolution to clonal disease is common:

  • Overall 15% of the cases develop clonal disease like MDS or PNH

  • Much higher after immunossuppression that BMT



Relapse
Relapse: Acquired Aplastic Anemia.

  • Definition:

    • Decrease in any of the peripheral cell counts to less than 50% of the median sustained counts during remission.

    • Return of the counts to levels meeting the definition of severe aplastic anemia.

    • Or by resumed need of blood transfusion support.

  • Risk: 35% at 11 years

    • 45% at 5 years

    • and reaches plateau at 64% between 7 to 10 years


Remission criteria: Acquired Aplastic Anemia.


Relapse after initial treatment Acquired Aplastic Anemia.


Failure free survival in patients treated Acquired Aplastic Anemia.

with ALG and ALG+CsA


Current and future treatment strategies
Current and Future treatment strategies Acquired Aplastic Anemia.

  • Evaluation of the best timing of immunosuppression

  • Multidrug immunosuppression vs sequencial immunosuppression

  • Early retreatment with immunosuppression

  • Improvement of current protocol

    • dose of G-CSF

    • newer growth factors like stem cell factor

  • New immunosuppresive protocol

    • high dose cyclophosphamides

    • new immunosuppressive treatment


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