 So, let's talk about the varying types of leukemias. We'll start with acute lymphoblastic leukemia, also known as ALL. ALL is most commonly seen in children than adults, but it can be seen in adults as well. Adults that have ALL do have a worse prognosis for the disease. What we see is a peripheral blood and bone marrow that has a very large increase in lymphoblasts. If you look at this picture, you will see quite a few lymphoblasts in this blood smear. All of these purples with a very, very small cytoplasm are lymphoblasts that are overwhelming the blood smear. The test for this to find out what type of lymphoblastic leukemia this is, we look for the TDT+, which is a marker for the pre-T and pre-B cells. We also check for that CD10, which is a pre-B cell marker. These two markers will indicate that this is an ALL versus a CLL or a hairy cell. ALL is the most responsive leukemia to treatment, so it has a very high cure rate, especially in the children. The treatment regimen for ALL is an intensive induction chemotherapy. This will cause a decrease in the prognosis for older individuals, because they may not be able to sustain the treatment of an intensive chemotherapy without the side effects that can come from it. Therefore, elderly people, specifically in their 80s and beyond, have a survival range of 5 to 10 months, whereas we can completely cure this in younger people. This is often seen as with metastasis to the CNS as well as to the testes. It does have a translocation 1221, and this translocation actually indicates that it has a better prognosis. One further thing to note here is that ALL is associated with Down syndrome, also in Trisomy 21. Next, we're going to talk about chronic lymphoblastic leukemia. CLL is commonly seen in patients that are greater than 60 years of age. It is the most common adult leukemia, and to differentiate this between ALL, we test for the markers, and the markers for CLL is CD20, CD23, and CD5. CLL is a very slow progressing tumor and cancer, and therefore it's sometimes difficult to detect because the side effects and the symptoms that show up are a little more difficult to find with that slow progression. CLL is seen on a light microscope blood smear as smudge cells, and you can see that here in this photo with these small little smudges that are small little crushed lymphocytes. You can kind of remember this as CLL stands for Crushed Little Lymphocytes, and the Crushed Little Lymphocytes, that's your smudge cells. Moving on, let's talk about the hairy cell leukemia. Hairy cell leukemia is a mature B cell tumor. This is seen on a blood smear as filamentous hair like projections, and you can see that in this picture over here. You've got your lymphocyte, and it looks like there's small little pieces of hair sticking out from this lymphocyte all around, and each one of these has that same indication. So that's our hair like projections that you can see on a light microscope. What's happening here is we're having marrow fibrosis, and then these cells are having trouble getting out of the bone marrow, and you're rupturing some of the outer cell. This fibrosis will also lead to a dry tap on a bone marrow aspiration, so if you do a bone marrow biopsy, you're going to get nothing out. You won't get any fluid or any bone marrow out. You do see splinomegaly and pancytopenia with hairy cell leukemia. Those leukocytes are going to be gumming up the spleen, making it bigger and bigger. The stain for hairy cell leukemia is abbreviated as TRAP, T-R-A-P, and that is tartrate-resistant acid phosphatase. TRAP. You can remember that as TRAP in a hairy situation, so if you use a TRAP stain and it comes back positive, you can see that as a hairy cell leukemia. There are also BRAF mutations associated with hairy cell leukemia, and we treat this with cladrobine and pentastatin.