Hemtopathology IV Flashcards
What are the 4 main types of chronic myeloproliferative disorders (MPD)?
- Chronic myelogenous leukemia (CML)
- Polycythemia vera (predominantly red blood cells)
- Primarymyelofibrosis
- Essential thrombocytosis (platelets)
What is the common target of the chronic myeloproliferative disorders?
Multipotent Myeloid Progenitor Cells - CML is different though as it affects a pluripotent stem cells that gives rise to BOTH lymphoid and myeloid cells
What are some common features of the MPD?
- Splenomegaly
- All can progress to acute leukemia
- “Spent phase” where marrow fibrosis and cytopenia occurs as cells are worn out
- Mutated activated tyrosine kinases
What is the tyrosine kinase mutation in CML?
BCR-ABL
What is the tyrosine kinase mutation in polycythemia vera?
JAK2
ET and Primary Myelofibrosis
JAK2, CALR, MPL
What is the classic chromosome abnormality found in CML?
Philadelphia Chromosome
What is the transaction of the Philadelphia Chromosome?
This abnormality represents a reciprocal translocation between the ABL gene on chromosome 9 and the BCR gene on chromosome 22 - the BCR-ABL codes for a fusion protein with tyrosine kinase activity
What are the findings with CML?
- There is a marked increase in neoplastic granulocytic precursors in the marrow
- Bone marrow is close to 100% cellular
- Increased numbers of megakaryocytes
- Erythroid progenitors are usually normal or decreased
What is the normal proportion of RBCs to WBCs?
1000:1
What is the ratio of RBCs to WBCs in CML?
It can be as low as 10:1
How can you distinguish between CML and a leukemoid reaction?
CML: WBCs Usually >50,000 All stages of maturation Marked splenomegaly 9;22 BCR-ABL mutation
Leukemoid Reaction:
WBCs Usually less than 50,000/L
Almost all mature
NO 9;22 BCR-ABL mutation
What is the LAP score in CML versus leukemoid reaction?
LAP will be reduced in CML and elevated in a leukemoid reaction
What is the onset of CML like?
Insidious
What is the accelerated phase of CML?
About 50% of patients eventually enter “accelerated” phase with decreased response to treatment, increasing anemia and thrombocytopenia, sometimes striking peripheral blood basophilia, additional cytogenetic abnormalities