Student questions about myeloproliferative disorders
Posted Dec 01 2009 10:05pm
Here are some real student questions about myeloproliferative disorders. You should always ask questions when you don’t understand something – preferably in lecture. If you don’t understand something, at least 5 other people are having the same problem.
Q. Can chronic myelofibrosis lead to anemia?
A. Yes! It can lead to anemia because the marrow eventually get so full of fibrosis that there is no room for the red cells (and all the other cell types) to grow. The cells try their best to grow elsewhere, but it’s never as good – and patients eventually get anemic.
Q. With polycythemia vera, are both the bone marrow and blood full of red cells?
A. Yes! In polycythemia vera, there is a panmyelosis (like in all myeloproliferative disorders), but the line that’s dominant is the red cell line. The marrow is stuffed with them, and they spill out into the blood as mature red cells. The RBC goes way up, and the blood gets more viscous and sludgy. One way to treat these patients is to do periodic phlebotomy to get rid of the excess red cells.
Q. In essential thrombocythemia, are there an increased number of megakaryocytes seen in marrow and blood too? Do megakaryocytes escape the marrow since there is a malignant proliferation?
A. Yes, there is an increased number of megakaryocytes in the marrow! They end up making a TON of platelets, which spill into the blood. The megakaryocytes do not spill into the blood because they are HUGE – too big to get out.
Q. Would essential thrombocythemia be considered an underlaying cause of DIC? Is the high count of platelets consistent or does it fluctuate?
A. Essential thrombocythemia is not considered a cause of DIC. There are definitely a ton of platelets around – and sometimes they can sludge up into little vessels – but they don’t really initiate the coagulation cascade, like DIC does (in DIC, the problem is not only that you have platelet clots all over, but you’re sealing them up with fibrin. When the red cells try to go through, they get snagged on the fibrin strands). The high count remains pretty consistently high, unless you treat the patient. By the way, patients with essential thrombocythemia can either have abnormal clotting or abnormal bleeding (they can actually develop a secondary (or “acquired”) von Willebrand disease! Weird! So can some of the other myeloproliferative disorders.).
Q. Are chronic myeloproliferative disorders incurable?
A. All chronic leukemias – myeloproliferative disorders and lymphoproliferative disorders – tend to be slowly-progressing, incurable disorders. The exception is chronic myeloid leukemia, which is a relatively (compared to the other chronic leukemias) faster-progressing disorder. It also has a really, really good treatment now – a drug called imatinib (or Gleevec) that can essentially halt the progression of the disease. It doesn’t really ”cure” CML, but it does turn it into a chronic disease that people can live with for many many years.