Miscellaneous Red Cell Abnormalities
In the chapter of Miscellaneous Red Cell Abnormalities, we will discuss some of the commonly seen red blood cell abnormalities.
Adult human bone marrow synthesizes 4 X 1014 molecules of hemoglobin every second. Heme and globin chains (alpha and beta) in adults are manufactured in separate cell compartments—mitochondria and cytoplasm, respectively—and then combined in cytoplasm in an amazingly accurate manner. Four major problems can manifest during this delicate process:
- Qualitative defects of globin chain synthesis result in hemoglobinopathies such as sickle cell disease.
- Quantitative defects of globin chain synthesis result in hemoglobinopathies such as thalassemia.
- Defects in synthesis of the heme portion result in porphyrias.
- Defects involving incorporation of iron into the heme molecule result in sideroblastic anemias.
Howell-Jolly bodies are nuclear remnants and occur predominantly following splenectomy and in hyposplenic conditions such as coeliac disease. Post-splenectomy blood films show also the following features: target cells, acanthocytes, spherocytes, nucleated red cells, Pappenheimer bodies and Heinz bodies. The spleen is also responsible for the surface remodeling of red cells.
Following splenectomy, other blood changes including transient leucocytosis and thrombocytosis are commonly seen.
- Basophilic stippling is probably due to degenerate microsomes and siderosomes.
- They are found in lead poisoning, other toxic conditions such as severe infections, myelodysplastic Syndrome, sideroblastic anemia, TTP and in thalassemia.
Congenital Dyserythropoietic Anemias (CDA)
- This is a group of rare hereditary anemias in which there is ineffective erythropoiesis with erythroid cell death within the bone marrow.
- Megaloblastoid changes may occur erythroid multinuclearity is typical.
- There are at least three varieties of CDA one of which (CDA II) is associated with lysis of the RBCs by acidified group matched allogeneic sera (Ham’s test).
- These are a group of dyserythropoietic disorders in which iron-containing granules (demonstrated by Prussian blue stain – Perls’ reaction) surround the nuclei of some erythroblasts.
- The disorder may be hereditary or acquired.
- The acquired form may be secondary to certain drugs (e.g. antituberculous agents like isoniazid), lead poisoning, other toxic conditions, nutritional deficiencies (copper, vitamin B6), alcohol, as a clonal disorder (myelodysplasia) which may progress to acute leukemia or idiopathic.
- Treatment of sideroblastic anemia may include removal of toxic agents; administration of pyridoxine, thiamine, or folic acid; transfusion (along with antidotes if iron overload develops from transfusion); other medical measures; or bone marrow or liver transplantation.
Alcohol-induced bone marrow damage
- Excessive alcohol intake can result in dyserythropoiesis as well as morphological changes due to vitamin deficiencies.
- Bone marrow findings took the form of ineffective erythropoiesis associated with impaired iron utilization, vacuolated proerythroblasts, multinuclear erythroblasts, megaloblasts and iron-containing plasma cells as well as vacuolated precursor cells of the granulocytopoietic series.
- In the differential diagnosis, alcohol-induced bone marrow damage is to be distinguished from the myelodysplastic syndrome of the RA and RARS form.
- Alcohol-induced bone marrow damage is reversible. The toxic defect probably does not reside in the stem cell but is more peripheral.