Aplastic and Hypoplastic Anemias

APLASTIC ANDHYPOPLASTIC ANEMIAS

Waggas Elaas

APLASTIC ANEMIA

Aplastic anemia is a severe, life threateningsyndrome in which production of erythrocytes,WBCs, and platlets has failed.

Aplastic anemia may occur in all age groupsand both genders.

The disease is characterized by peripheralpancytopenia and accompanied by ahypocellular bone marrow.

Pancytopenia : a reduction in blood count of all cell lines, WBCs, RBCs, platelets.

PATHOPHYSIOLOGY

The underlying defect in all cases appears to be areduction in the number of haemopoietic

pluripotential stem cells, and a fault in the

remaining stem cells or an immune reaction againstthem, which makes them unable to divide anddifferentiate sufficiently to populate the bone marrow

CAUSES OF APLASTIC ANAEMIA.

Secondary

Primary

Ionizing radiation:accidental exposure (radiotherapy,radioactive isotopes, nuclear power stations)

Congenital(Fanconi,s &Non Fanconi,s

Chemicals :benzene, organophosphates and other organicsolvents, DDT and other pesticides, organochlorines,recreational drugs

Idiopathicacquired

Drugs: busulfan, chloramphenicol,

Viruses: viral hepatitis (non-A, non-B, non-C, non-G inmost cases), EBV

OTHER CAUSES OF PANCYTOPENIA

Acute leukaemia

Megaloblastic anaemia

Paroxysmal nocturnal haemoglobinuria (PNH)

Myelofibrosis

Splenomegaly

Myeloma or lymphoma

CLINICAL FEATURES

At any age with a peak incidence around 30 years.

A slight male predominance.

symptoms and signs resulting from anaemia, neutropeniaor thrombocytopenia.

Infections, particularly of the mouth and throat, arecommon and generalized infections are life-threatening.

Bruising, bleeding gums, epistaxes and menorrhagia arefrequent, and the usual presenting features, often withsymptoms of anaemia.

The lymph nodes, liver and spleen are not enlarged.

LABORATORY FINDINGS

 Anaemia is normochromic, normocytic or macrocytic

lowThe reticulocyte count is usually extremely low

 Leucopenia. There is a selective fall in granulocytes,

usually but not always to below 1.5 x 109/L.

In severe cases, the lymphocyte count is also low.

The neutrophils appear normal.

Thrombocytopenia is always present and, in

severe cases, is less than 20 x 109/L.

There are no abnormal cells in the peripheral blood.

The bone marrow is hypocellular, with loss of

haemopoietic tissue and replacement by fat which

comprises over 75% of the marrow.

The main cells present are lymphocytes and plasma cells.

Megakaryocytes in particular are severely reduced orabsent.

The disease must be distinguished from other causesof pancytopenia.

This is done by examination of the bone marrowsamples for Cytogenetic analysis, flow-cytometry, andfor morphology of cells and the marrowmicroenviromnent.

HYPOCELLULAR BONE MARROW INAPLASTIC ANEMIA

HYPOCELLULAR

NORMOCELLULAR

RELATED DISORDERS

1. Pure red cell aplasia

Characterized by a selective decrease in erythroid precursor cells inthe bone marrow. WBCs and platlets are unaffected.

2. Congenital dyserythropoietic anaemia.

Hereditary refractory anaemias characterized by ineffectiveerythropoiesis and erythroblast multinuclearity.

3. Myelodysplastic syndromes

primary, neoplastic stem cell disorders that tend to terminate inacute leukemia