Transcription
Médicos is perfection. Alice once again with a new topic, and today let's talk about hairy cell leukemia. How do you like this hairy guy? I love him. [Music]
In the good old days, hairy cell leukemia used to be known as different things, such as histiocytic leukemia, malignant ridiculous lymphoid myelofibrosis, leukemic reticulo-endothelial system. Eeeh, better it's a description that the leukemia will have hairy cells on peripheral smear. Give me a break. Leukemic reticulo-endothelial system. In if your book still have any of these names, there is no hope for you; you're living under a rock, literally.
So, before we talk more about hairy cell leukemia, let me remind you of my challenge. I need your help to reach 25,000 subscribers. Once I hit that goal, we can start a new series. I know hematology and oncology can be boring, so please consider sharing my videos; it really helps me. Okay.
Hairy cell leukemia: rare type of leukemia. It's indolent, which means subtle. This is opposite to aggressive. Some texts recognize it as a subtype of CLL. Also, hairy cell leukemia can be accompanied by some components of lymphoma, specifically non-Hodgkins lymphoma. So again, this is an example of both leukemia and lymphoma in the same patient. What else we had? CLL together with SLL, small lymphocytic lymphoma, as an example of leukemia and lymphoma in the same patient again. Think lemon and lemonade, as I've told you before. We have the BRAF V600E mutation, C11C+, and we have overexpression of cyclin D1.
What are the hairy cells? Hairy cells are mature B lymphocytes. Okay.
What is the demographics? Middle-aged Caucasian male is usually the patient of hairy cell leukemia. Leukemic cells will accumulate in this plane, leading to splenomegaly, leading to early satiety and abdominal discomfort. Leukemic cells will crowd out other cell lines, such as red blood cells, leading to symptoms of anemia; white blood cells, leading to symptoms of leukopenia; and platelets, leading to the symptoms of thrombocytopenia. Notice here that the hairy cells are mature; that's why we considered it as a subtype of CLL, which is a mature chronic leukemia. There are some theories that hairy cell leukemia is linked to farming and gardening activity. Also, sometimes patients with high tumor burden of hairy cell leukemia may have low cholesterol levels in their blood. So here is a fun way for it: if you'd like to have low cholesterol levels in your blood, go do some gardening. Of course, this is a joke.
What is the pathophysiology of hairy cell leukemia? These hairy cells, which are B lymphocytes, will accumulate in the bone marrow. Also, reticular fibrosis will occur in the bone marrow; reticulan fibers. This will lead to site opinion. Also, the spleen will undergo something called splenic sequestration, marginalization, attacking and destroying blood cells, leading to against site opinio. In the lymph nodes, we find B cells in the cortex and T cells in the para cortex. In the spleen, we find both B lymphocytes and T lymphocytes in the white pulp of this plane. First, the blood enters the white pulp; then you have the lymphocytes to attack the invaders to the spleen. B lymphocytes are particularly present in the peripheral areas of the white pulp. T lymphocytes are present in the peri-arteriolar lymphatic sheath, or PALS.
Now let's go to hairy. So, looking something weird happens, and instead of seeing the B lymphocytes in the white pulp, we see these abnormal neoplastic B lymphocytes called the hairy cells in the red pulp. I don't know why that is, but this is just the way it is. Clinically easy. Since the spleen is involved, you will have splenomegaly involving the red pulp. A spleen will lead to abdominal discomfort and early satiety. Hepatomegaly, of course, bad. Splenomegaly is common in hairy cell leukemia. Okay. Crowding out of the normal population of blood cells will lead to site opinion. You'll have symptoms of anemia, leukopenia, and thrombocytopenia. There is cutaneous vasculitis in cases of hairy cell leukemia. This is high-yield. Also, there is no lymphadenopathy in cases of hairy cell leukemia. I don't mean zero, but it's less than ten percent. So when I've told you earlier in the lecture that hairy cell leukemia sometimes is associated with non-Hodgkins lymphoma, this is true, but rare; less than ten percent of cases. Also, in here is a leukemia; there is decreased humoral and cell-mediated immunity by the B and T lymphocytes, respectively.
We can never do hematology or oncology without going to the lab, so let's go to the lab. On peripheral smear: lymphocytes with cytoplasmic or hairy projections. There are short, tiny projections of the B lymphocyte. Let's go stain them with TRAP, tartrate-resistant acid phosphatase. They stain positively to TRAP. This is sensitive but not specific. Okay, so it rules out, but it doesn't rule in the disease. Okay, I need something specific now. Okay, let's go to immunohistochemistry, also known as flow cytometry, also known as immune phenotyping. You will have CD103 positive, CD11C+, CD25 positive. Also, the B-cell markers will be positive, why? Because the hairy cells are B lymphocytes. So CD19 positive, CD220 positive, CD222 positive. Annexin A1 is specific but not sensitive. Bone marrow aspiration: usually dry tap. It's very difficult to aspirate this bone marrow. Why? Bone marrow fibrosis. I've told you reticulan fibers accumulate in the bone marrow. If you are successful and can aspirate, you'll find neoplastic cells and reticulum fibrosis in this, as well as pallor and fatigue on physical exam. There is splenomegaly. On peripheral smear, you'll find this kind of cell. Platelet count is seventy thousand. Attempt to perform bone marrow aspiration yields a dry tap.
Question number one: What's the most likely diagnosis? Question number two: What's next? Look for that t(9;22) translocation, do a PAS stain, do immune phenotyping, or test for cryoglobulin.
Next question regarding the same case: Few weeks later and before any medical treatment or intervention, this patient's peripheral smear started showing these cells. I'll help you by telling you that all of them are abnormal red blood cells. The question is: Which of the following should you deduce? Is this a blast crisis? Is this leukostasis? Does that mean that neoplastic cells have invaded the spleen? Or is it an immune hemolytic anemia? So let me know the answer to these three questions down below in the comment section, and let's see who will get it first.
Now let's examine these old names, and some of them will start to make sense. Histiocytic leukemia? No, this is wrong; it's not histiocytic, it's lymphocytic. Leukemia hairy cell leukemia is malignant reticulocyte? Yes, it's a malignancy; that's true. Ridiculous? Yes, it's a condition of reticulan fibers being in your bone marrow, called bone marrow fibrosis; that's why we get a dry tap. Lymphoid myelofibrosis? That's very good. Lymphoid, yes, it's a lymphoid leukemia. Myelofibrosis meaning fibrosis of the bone marrow. Leukemic reticulo-endothelial system? Endothelial system includes the spleen, and you have splenomegaly, whether leukemia. Also, don't forget that the liver is one of the reticulo-endothelial organs, and in hairy cell leukemia you can get hepatomegaly.
That's it, guys. Thank you so much for watching, and if you like this video, please consider supporting this channel on Patreon. Go to this website. You can support me by giving one dollar a month; it will help me produce more videos, plus you will get early access to the plus other notes. Thank you so much, and as always, be safe, stay happy, and study hard.