Aplastic Anemia

pancytopenia

acts a s an autoimmune disorder in which the T cells attack the patient's own marrow.

That's why medications like antithymocyte globulin (ATG) and cyclosporine are useful and brings the marrow back to life. (Tacrolimus is an alternative)

Myelophthisic anemia

is anemia caused by replacement of marrow by other constituents, either abnormal hematopoietic cells or nonhematopoietic cells. These, in effect, "push out" the normal marrow constituents leading to the anemia.

If the underlying disease process is (not very common) myelofibrosis or a (rare) hereditary storage disease, splenomegaly (sometimes massive) related to either extramedullary hematopoiesis or underlying disease process may be present.

When the underlying disease process is an end-stage cancer (common) or granulomatous disease (less common), splenomegaly is usually not seen because little extramedullary hematopoiesis occurs.

Dx

film:

presence of red blood cells that contain nuclei or are teardrop-shaped (dacryocytes), or immature granulocyte precursor cells which indicates leukoerythroblastosis is occurring because the displaced hematopoietic cells begin to undergo extramedullary hematopoiesis.

The fragmented and distorted cells seen in anemias due to this type of process are the result of trauma to erythrocytes going through distorted and compressed capillary beds.

Diagnosis is confirmed when a bone marrow biopsy demonstrates significant replacement of the normal bone marrow compartment by fibrosis, malignancy or other infiltrative process. The presence of immature blood cell precursors helps distinguish another cause of pancytopenia, aplastic anemia, from myelophthisic anemia because in aplastic anemia the hematopoietic cells are damaged and immature blood cells are not seen in the peripheral blood.

Treatment

involves management of the underlying disease, if possible, with transfusions indicated if the anemia produces cardiovascular symptoms.

Erythropoietin is often tried in these settings, but typically produces only a modest response since the underlying problem is a lack of marrow room rather than stagnant erythrocyte development.

Fanconi's anemia

the most common congenital cause of aplastic anemia.