uworld said that a major difference between myelofibrosis and aplastic anemia is that you DONT get extramedullary hematopoesis with aplastic anemia. Could someone explain why? I though you get extramedullary hematopoesis in repsonse to anything that decreases the ability to produce heme.
Extramedullary hematopoesis
- Thread starter Step1Hash
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Just a thought, nothing in print to back me up, but isn't aplastic anemia mainly due to drugs or virus such as parvovirus B19? Would the cause of the aplastic anemia suppress the normal extramedullary sites in a similar manner as the bone marrow?
not 100% but isn't aplastic anemia a defect in progenitor cells, so even if the body wanted EMH, there's no cells to perform the task (as mentioned above rapid loss due to drugs rxn, bugs, radiation, ect). myelofibrosis the process of marrow loss is more gradual (relatively speaking to aplastic crises) so progenitors have time to migrate/escape the marrow and make it to the spleen/liver. i think goljan uses the 'teardrop' shaped RBCs story for myelofibrosis? I could be totally wrong, but that's what came to mind, hope it helps.
Thanks! So basically the primary issue in aplastic anemia is with the stem cells themself and in myelofibrosis the primary issue is the fibrosis leading the stems cells to migrate as a reaction.
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Yeah thats my impression as well.
Also think about this: In aplastic anemia, the insult is usually something that hits everything at once, either radiation, an infection, or a toxin, theres no time for them to escape and the cells get slaughtered and leave empty spaces in the bones. In myelofibrosis, there is a subset of proliferating cells that causes the trouble so there is time for the normal ones to go somewhere else but they're sad about it so you get teardrop cells.
