Red Cell Disorders I Flashcards
How long does it take to erythroblasts to fully mature?
7 days
What is the primary growth factor for erythropoiesis?
EPO
Explain the termsanisocytosis, poikilocytosis and anisopoikilocytosis.
Anisocytosis = varying sizes.Poikilocytosis = varying shapes.Anisopoikilocytosis = variation in size and shape.
What is RDW and explain its significance.
Red Cell Distribution Width, it is a measure of the variation in size of RBCs. Congenital anemias for example have low RDW (they are more consistent in size) whereas acquired anemias such as iron deficiency anemias have high RDWs.
What are reticulocytes?
Immature RBCs that are released from the bone marrow that eventually mature to form functioning RBCs, they survive in the circulation for 1 day.In case of increase hematopoiesis the number of reticulocytes increases dramatically which can be seen on peripheral blood smear, this corresponds to an increase in EPO.
What is another name of reticulocytes?
Polychromatophilic erythrocytes.
What are the clinical features of anemia?
- Pallor of skin, nail beds, buccal mucosa
- Fatigue, weakness, malaise
- Dyspnea on exertion
- Syncope, headache, visual disturbances
- Tachycardia
- Angina
- Cardiac failure
Explain the causes of hypoproliferative anemia.
It is due to either inadequate or ineffective production (aka ineffecitve hematopoiesis). Bone marrow failure due to
- Aplastic anemia
- Pure red cell aplasia
- Iatrogenic
- Bone marrow infiltration/replacement (myelophthisis) Nutritional deficiency
- Iron deficiency (microcytic)
- Megaloblastic anemia (macrocytic)
- Anemia of chronic disease (microcytic)
- Myelodysplastic syndromes (macrocytic)
Explain aplastic anemia.
Caused by failure or destruction of myeloid stem cells due to:
* Radiation and drugs (benzene, chloramphenicol, alkylating agents, antimetabolites)
* Viral agents (parvovirus B19, EBV, HIV, hepatitis viruses)
* Fanconi anemia (DNA repair defect causing bone marrow failure); also short stature, incidence of tumors/leukemia, café-au-lait spots, thumb/radial defects
* Telomerase defects, acquired stem cell defects, potential for acquiring further mutations and tranforming into AML
* Idiopathic (immune mediated, 1° stem cell defect); may follow acute hepatitis
Findings: Decrease in reticulocyte count, there are high levels of EPO.
* Pancytopenia characterized by severe anemia, leukopenia, and thrombocytopenia. Normal cell morphology, but hypocellular bone marrow with fatty infiltration (dry bone marrow tap).
Symptoms: fatigue, malaise, pallor, purpura, mucosal bleeding, petechiae, infection.Treatment: withdrawal of offending agent, immunosuppressive regimens (eg, antithymocyte globulin, cyclosporine), bone marrow allograft, RBC/platelet transfusion, bone marrow stimulation (eg, GM-CSF).
Explain Pure Red Cell Aplasia.
- Disorder of erythroid progenitor cell causing decreased erythropoiesis
- Incidence –very rare
- Clinical features: Anemia – pallor, weakness, fatigue
Pathogenesis and etiology Highly associated with Thymoma (paraneoplastic syndrome) - Viral infections (parvovirus B19)
- Drugs
- Autoimmune disorders
Pathology: - Normochromic, normocytic anemia, no poikilocytes
- There aremarkedly decreased erythroid precursors in the bone marrow
- Intranuclear inclusions in erythroblasts in parvovirus B19 infection
Treatment: androgens, plasmapheresis, thymectomy, supportive - transfusions.
Explain myelophthisic anemia.
Decreased erythropoiesis due to bone marrow infiltration or replacementClinical features
* Anemia –pallor, weakness, fatigue
* Features of underlying disease
Pathogenesis and etiology
* Metastatic cancer
* Fibrosis (primary myelofibrosis or following treatment)
* Hematopoietic neoplasms
Pathology
* Normochromic, normocytic anemia
* Teardrop shaped erythrocytes (poikilocytes)
* Circulating nucleated red blood cells
* Granulocytic left shift (leukoerythroblastosis)
* Replacement of normal bone marrow elements is seen on H&E
