Acute myeloid & lymphoblastic leukemia – causes, symptoms & pathology

Acute myeloid & lymphoblastic leukemia – causes, symptoms & pathology


Learning medicine is hard work osmosis makes it easy It takes our lectures and notes to create a personalized study plan with exclusive videos practice questions and flashcards and so much more Try it free today With acute leukemia Luke refers to white blood cells and emia refers to the blood so in acute leukemia There’s uncontrolled proliferation of partially developed white blood cells also called blast cells Which build up in the blood over a short period of time? although leukemia specifically means cancer of the white blood cells It can also be used to refer to cancer of any of the blood cells including red blood cells and platelets Acute leukemia can be broadly classified into acute myeloid leukemia or AML and acute lymphoblastic leukemia or a ll AML is more common in old age. Whereas a ll is more common in children in both cases accumulation of blast cells interferes with the development and function of healthy white blood cells platelets and red blood cells Every blood cell starts its life in the bone marrow as a hematopoietic stem cell hematopoiesis are pluripotent meaning that they can give rise to both myeloblasts which are precursors of myeloid blood cells and lymphoblasts which are precursors of lymphoid blood cells These lymphoblasts can be pre b-cells which develop into B lymphocytes or pre T cells which you guessed it develop into T lymphocytes if a hematopoietic stem cell develops into a myeloid cell it’ll mature into an erythrocyte or a red blood cell a Thrombocytes or a platelet or a leukocyte, which is a white blood cell like a monocyte or a granulocyte Granulocytes ourselves with tiny granules inside of them They could be neutrophils basophils or eosinophils If a hematopoietic stem cell develops into a lymphoid cell on the other hand It’ll mature into some other kind of leukocyte a t-cell b-cell or natural killer cell which are referred to as lymphocytes Once the various blood cells form They leave the bone marrow and travel around the blood or settle down in tissues and organs like the lymph nodes or the spleen Acute leukemia is caused by a mutation in the precursor blood cells in the bone marrow in the case of a ll it’s Usually due to a chromosomal translocation or an abnormal chromosome number common chromosomal translocations include translocation of chromosome 12 and 21 and Translocation of chromosomes 9 and 22 also called the Philadelphia chromosome these result in production of abnormal intracellular proteins which affect the cells function and cell division a ll can further be classified into T cell al where there’s proliferation of T cell precursors and B cell al where there’s proliferation of B cell precursors a ml is caused by a wide variety of abnormalities like chromosomal translocations, which are used to sub classify a ml into a few different types a Ml can be classified based on the morphology of the myeloblast Into a ml without maturation a ml with minimal maturation a ml with maturation acute promyelocytic leukemia acute Myeloma, no static. Leukemia acute monocytic leukemia Acute erythroid, leukemia and acute mega kareoke leukemia of these acute promyelocytic leukemia Is an important subtype it’s characterized by translocation of chromosomes 15 and 17 which disrupts the retinoic acid receptor alpha gene Which is required for normal cell division Now there are certain conditions that can actually lead to a ml like Myelodysplastic syndrome, which is characterized by defective maturation of myeloid cells and buildup of blasts in the bone marrow Usually the build-up is initially less than 20% lasts, but that’s enough to cause a decrease in the function of red blood cells granulocytes and platelets as The disease progresses the blast percentage may go over 20% Resulting in AML with a background of myelodysplasia Another condition often associated with both AML and CML is Down syndrome Which is caused by an extra 21st chromosome so that there’s a trisomy 21 finally, there are also some other risk factors for acute leukemia like exposure to radiation and Alkylating chemotherapy, which may have been used as treatment for some other type of cancer All right. Now regardless of the type of mutation acute leukemias share a similar pathogenesis The mutation does two things First it causes the precursor blood cells to lose their ability to differentiate into mature blood cells This means that they’re stuck in the blast stage of development and the blast cells don’t function effectively Second it makes the blast cells divide uncontrollably And in this process take up a lot of space and nutrition in the bone marrow this means that the other normal blood cells growing in the bone marrow get crowded out and It’s tough for them to survive with the extra competition for nutrients This causes Saito penis or a reduction in the number of healthy blood cells like anemia which is a reduction of healthy red blood cells thrombocytopenia a reduction of healthy platelets and leukopenia or a reduction of healthy leukocytes as The number of these blast cells in the bone marrow keeps increasing they spill out into the blood now some of these little guys especially lymphoblasts settle down in organs and tissues across the body like in the liver and spleen Sometimes pre T cells in T cell ALL migrate to the thymus or lymph nodes like normal T cells do and they settle down there causing these structures to enlarge Also an acute promyelocytic leukemia The promyelocytes activate the clotting process and this combined with the already decreased platelets results in disseminated intravascular coagulation Symptoms of both AML and a ll include fatigue because of the anemia easier bleeding because of the Thrombocytopenia and more frequent infections because of the leukopenia Pain and tenderness and the bones can occur when there’s increased cell production, which causes the bone marrow to expand hepatosplenomegaly often causes a feeling of abdominal fullness while the lymph adenopathy Often causes mild but localized pain in the lymph nodes However, hepatosplenomegaly and lymph adenopathy are both seen more prominently in a ll rather than AML In addition monocytic variety of AML causes swelling of gums because of monocytic infiltration Thymus enlargement and T ALL may present as a mass or growth in the mediastinum The diagnosis of AML and a ll usually starts with a peripheral blood smear which shows a lot of blasts cells Milo blasts in the case of AML and lymphoblasts in the case of a ll this is usually followed up by a bone marrow biopsy, which also shows an increase in blast cells an acute leukemia the percentage of blast cells in the bone marrow goes up from their normal value of one to two percent to greater than 20% an Important step in the diagnosis is to differentiate AML from a ll this can be done by identifying the blast cells as either myeloblast or lymphoblasts in a specially stained smear myeloblasts are usually large cells with nuclei containing fine chromatin and prominent nucleoli a classic feature of myeloblast sin AML especially acute promyelocytic leukemia Is the presence of our rods in the cytoplasm which are crystallized aggregates of the myeloperoxidase enzyme on? The other hand lymphoblasts are relatively smaller cells with coarse chromatin which are clumped together and have small nucleoli Lymphoblasts have very little cytoplasm which has glycogen granules In Addition amino phenotyping is done to detect certain markers. For example TDT which is a DNA polymerase that’s present only in the nucleus of the lymphoblast is therefore a marker for them and CD 10 is a surface marker for pre b-cells Treatment of acute leukemia is mainly aimed at reducing the number of blast cells to allow the other blood cells to develop normally Treatment of AML and AOL is based on the type and stage of the cancer but in general involves chemotherapy biological therapy stem cell transplants or bone marrow transplants acute promyelocytic leukemia Can be treated with all-trans-retinoic acid Or atra, which is a derivative of vitamin A atre binds to the disrupted retinoic acid receptor and causes The blasts to mature into neutrophils which like all things eventually go on to die Thereby cleaning out a lot of the blasts from the blood All right as a quick recap acute leukemia is a cancer of the blood cells and is classified into AML and a ll AML can be further subdivided into different types based on cytogenetic abnormalities or blasts cell morphology Al L on the other hand is classified into t-cell al and b-cell, AOL Both AML and al l lead to accumulation of blast cells in the bone marrow Which interferes with the development and function of healthy white blood cells platelets and red blood cells Major symptoms include fatigue easy bleeding fever bone pain hepatosplenomegaly gum swelling in promyelocytic type and mediastinal mass in T ALL Thanks for watching if you’re interested in a deeper dive on this topic take a look at as Moses org where we have flashcards Questions and other awesome tools to help you learn medicine Otherwise, you can always support us by donating on patreon subscribing to our channel or following us on social media You

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