MKSAP 1: Hematopoietic stem cell and their disorders Flashcards
(90 cards)
Name the bone marrow failure syndromes
Aplastic anemia
Pure red cell aplasia
Neutropenia
What are the characteristics of aplastic anemia?
a condition characterized by pancytopenia with associated neutropenia, anemia and thrombocytopenia and a severely hypocellular bone marrow (<10%)
What the main etiologies of aplastic anemia?
Toxic, viral or autoimmune mechanisms
Define severe plastic anemia from very severe aplastic anemia?
Severe aplastic anemia has two or more of the following:
- ANC 200-500/uL
- Platelet count < 20K/uL
- absolute reticulocyte count <40K/uL
Very severe aplastic anemia has two or more the above except with ANC <200
What are some drugs that can cause aplastic anemia?
NSAIDs, beta-lactam abx, antiepileptic drugs and psychotropic meds
What is the dominant cause of adult AA?
autoimmunity as autoreactive T cells attack pluripotent HSCs and cause aplasia
What is first line therapy for aplastic anemia?
cyclosporine and antithymocyte globulin leads to control in 70% of adults. Allogeneic HSCT is a potentially curative therapy and should be considered for those younger than 50 with compatible donors
What are the 3 disorders that are acquired defects of the hematopoietic stem cell?
aplastic anemia
paroxysmal nocturnal hemoglobinuria
myelodysplastic syndromes
What is PNH?
Acquired disorder in which erythrocytes lack membrane proteins CD55 and CD59 required to stabilize complement leading to episodic intravascular hemolysis
What is the cardinal feature of pure red cell aplasia?
Severe anemia without an adequate reticulocyte response. Examination of bone marrow shows an absence of erythrocyte precursors
What is the mechanism for PRCA?
predominantly T cell autoimmunity or direct toxicity to erythrocyte precursors
List causes of PRCA
Parvovirus B19 Thymoma Autoimmune disease Lymphoid lukemia and lymphomas Solid tumors Drugs (phenytoin, isoniazid) Pregnancy Anti-EPO antibodies in patients receiving EPO
What specific subset of patients are susceptible to parvovirus B19 infection causing PRCA? What treatment may they require?
sickle cell anemia patients
Can cause severe anemic crisis
IVIG may hasten viral clearance
What diagnostic test is required to diagnose PRCA? What else does it exclude?
Bone marrow examination
Also excludes secondary causes of PRCA such as CLL or non-Hodgekin lymphomas
How do leukemias and lymphomas cause PRCA?
Immune mediated mechanisms
Name the T cell lymphoproliferative disorder that is associated with PRCA, is associated with RA, diagnosed by peripheral blood smear and shows lymphocyte CD57 positivity on flow cytometry
How can it be treated?
large granular lymphocytosis
Treated with methotrexate
define felty syndrome
clinical triad of RA, splenomegaly and neutropenia
How is thymoma excluded as a cause of PRCA?
CT scan of the chest
How are idiopathic causes of PRCA treated?
Immunosuppression with prednisone either administered alone or with cyclosporine or cyclophosphamide
What are the possible general causes of isolated neutropenia?
Hereditary, toxic or immune causes
What are the general categories of toxicities to cause neutropenia?
viral, bacterial or meds
Name the viruses that can cause neutropenia?
Acute HIV, CMV and EBV
What specific bacterial infections can cause neutropenia?
Rickettsial infection or overwhelming bacterial infection
What meds can cause neutropenia?
Cytotoxic chemos, NSAIDs, carbamazepine, phenytoin, PTU, cephalopsorins, Bactrim and psychotropic drugs