3Aplastic Anaemia Maj Gen Dr Muhammad Ayyub MBBS, PhD (London), MRCPath (London), FRCPath (UK)Prof & HOD AM College
4Outline Introduction Aetiology Pathogenesis Clinical features & diagnosisTreatmentParoysmal Nocturnal Haemoglobinuria (PNH)Case Study
5Definition of aplastic anaemia. Peripheral blood pancytopenia and a hypocellular marrow in which normal marrow is replaced by fat cells.Abnormal cells are not found.
6History of Aplastic anaemia. Paul Ehrlich ( ) described the first case of aplastic anaemia in a pregnant woman who died of marrow failure in1888.The term “aplastic anaemia” first used by Anatole Chauffard in 1904.
7Diagnosis of pancytopenia. Suspect from signs and symptomsMade by check of full blood count, FBCMaleFemaleHbg/dlg/dlPCV38-50%36-45%MCV80-100flMCH27-34pgWBC4-11x109/lNeutLymph1.5-4Platelet
8Normal Erythropoiesis. Red cell life span 120 days.Platelet life span 6 days.Granulocyte life span < 24 hours.Constant marrow activity needed to replace dead cells.
11Inherited marrow failure. Important diagnosis to make.Implications for treatment.Detailed history and examination.Nail dystrophy, skin pigmentation and leukoplakia may suggest dyskeratosis.Short stature, metaphyseal dysarthrosis, pancreatic exocrine deficiency or family history of cytopenia in Shwachman-Diamond syndrome.Check for gene mutations can help.
12Incidence of Acquired Aplastic Anaemia. Rare condition; 2-5/million per year<1 in Ipswich catchment per year.Incidence is higher in East, environmental as migrants have incidence of local population.male to female incidence = equalDisease of young adults, 2nd peak in 4th -5th decade of life.
13Pathogenesis. Primary defect or damage to haematopoietic stem cell. possible Immunological attack on stem cells.HLA-D2 is overrepresented in patients, suggests a role for antigen recognition.Defective microenvironment (i.e. marrow stromal defect)
15Pathogenesis 2Evidence shows marrow stromal cells have normal function.Normal growth factor production.Adequate marrow stromal function also evidenced by success of stem cell transplantation.
16Clinical Features. Anaemia; tiredness & fatigue, palpitations, SOB. Low white count; recurrent infections, flu-like illness.Low platelets; easy bruising and bleeding.
17Investigations. FBC Reticulocyte count Blood film. B12/folate. Liver function testsVirologyBone marrow aspirate & trephinePNH screen.
18Bone marrow aspirate in aplastic anaemia HypocellularAbnormal cytogenetics in 12% patientsTrisomy 6, 8, or 15 most common, similar outcome to no clone.Monosomy 7 may have poor outcome, suggests possible hypoplastic MDS.
19PNH screening. Paroxysmal nocturnal haemoglobinuria. Historically test was Ham’s test; showed red cell lysis by complement activation in acidified serum.Currently test for absent proteins on cell surface. CD55(DAF) and CD59(MIRL)
21Clinical course 1 Stable AA Pancytopenia remains stable over months to years.Greater the degree of pancytopenia the worse the prognosis. (see severe aplastic anaemia)
22Clinical course 2. Progressive or fluctuating aplasia. Initially small degrees of pancytopenia or single lineage cytopenia.Progressive sometimes following viral infections.Occasionally single cytopenia e.g. thrombocytopenia becomes true aplastic anaemia.
23Clinical course 3. Unstable Aplasia. Improvement in counts may be associated with abnormal clones.PNH clone in up to 20% of long term aplastic anaemia.Often only detected by lab tests and not clinically significant.
24Severe Aplastic Anaemia Peripheral Blood 2 of 3Granulocytes <0.5 x 109/lPlatelets <20 x 109/lReticulocytes <1%Marrow trephineMarkedly hypocellular <25% normal
25Treatment of aplastic anaemia. Supportive with blood products.Prophylactic antibiotics.Growth factor support.Androgens.Immunosuppressive therapy with antilymphocyte globulin & cyclosporin.Allogeneic stem cell transplantation.
26Immunosuppressive therapy Indicated for patients > 40 yearsPatients with no HLA matched sibling donors.Anti-Thymocyte Globulin(ATG) or anti-lymphocyte globulin (ALG), cyclosporin, methylprednisolone.Best results are for combination therapy.Response is slow, 4-12 weeks to see early improvement.
27Immunosuppressive therapy 2 Response rates 60-70%Relapses are common and continued supportive care needed.Up to 50% of relapsed patients will respond to 2nd course of immunosuppressive therapy.
30HLA identical sibling BMT Age <40 years.Conditioning with Cyclophosphamide & antithymocyte globulin, with cyclosporin and methotrexate.Long term overall survival = 80-90%Chronic graft versus host disease (GVHD) remains a problem for 25-40% of patients.
34New approaches to transplantation. Fludarabine based regimens.Umbilical cord blood transplants.
35PNHAn acquired haematopoietic stem cell defect with predominant haemolytic anaemia.A descriptive term for the clinical manifestation of haemolysis and haemoglobinuria manifest by dark coloured urine in the morning.
36PNH presentation Acquired haemolytic anaemia Thrombosis in large vessels e.g. hepatic abdominal, cerebral.Pancytopenia or aplastic anaemia.This triad makes PNH a unique syndrome
37PNH pathophysiology Acquired stem cell mutation defect Inability to synthesize the glycosyl-phosphatidylinositol (GPI) anchor that binds certain proteins to cell membranes.Gene (PIG A) located on X-chromosome.Complement regulating proteins DAF, MIRL are lacking on all haemopoietic cellsConsequent intravascular red cell destruction.Pathophysiology of thrombosis is not fully understood.
38PNH treatment Treat symptoms Folic acid for increased erythropoeisis May need iron if deficientTransfusionsAnticoagulationEculizumab (antibody against complement C5)Complement inhibition = risk of infection esp meningococcal. Vaccination required.
39Case study, further results Marrow aspirate cellularTrephine biopsy hypocellularPNH clone of 8-10% detected.Referred to London for 2nd opinion and treatment plan.Sibling not an HLA match.Given not requiring blood or platelet transfusion then no specific treatment was indicated.
40Case study Stable for 18 months Presented with headache & neck stiffness.Clinical impression of meningitis made.Initial CT scan no abnormalityCSF, no organismsMRI scan confirmed thrombosis.Started on anticoagulation.PNH clone had increased to 82%.
41Case study 4 weeks later admitted with further febrile episode. On antibiotics and anticoagulation.Developed left sided weakness and sensory loss.CT brain scan showed massive intracranial bleed.Transferred to neurosurgical centre at Addenbrooke’s hospital.
42New therapy for PNH Eculizumab anti complement therapy. Used in haemolytic disease with > 50% PNH clone.High cost £250k per yearNational commissioning Group (NCG) funded 2 centres nationally, Leeds and London.Equal access to treatment irrespective of address.
43Conclusions. Rare condition. Needs accurate diagnosis to ensure proper treatment.Still devastating outcomes for young adults.New treatments may further improve survival.
44Further ReadingPostgraduate Haematology, by Hoffbrand & Lewis Fifth EditionMaking Therapeutic decisions in adults with Aplastic Anaemia; Judith Marsh. ASH education program Book 2006.