Q. I was wondering what the difference was between labeling something as a “leukemia” vs labeling it as a “chronic myeloproliferative disorder.” I understand that leukemias are neoplastic proliferations of hematopoietic stem cells in the bone marrow, but aren’t myeloproliferative disorders the same thing? In particular, what category would chronic myelogenous leukemia be placed into? I have been grouping it with the MPDs, but then I get confused when I start to compare it to acute myelogenous leukemia, which is just labeled as a leukemia, and not a myeloproliferative disorder…?
A. You are right: leukemias are neoplastic proliferations of hematopoietic stem cells in the bone marrow. There are two big categories of leukemias: acute leukemias and chronic leukemias. The acute leukemias are divided into acute myeloid leukemia and acute lymphoblastic leukemia; the chronic leukemias are divided into chronic myeloproliferative disorders and chronic lymphoproliferative disorders.
Under these big acute and chronic categories, there are many different types of leukemia. Acute myeloid leukemia is divided into five main types: AML with genetic abnormalities (like t[8;21]), AML with FLT3 mutation, AML with multilineage dysplasia, therapy-related AML, and AML not otherwise categorized. ALL is divided into three main types: T-cell ALL, B-cell precursor ALL, and B-cell ALL (same as Burkitt lymphoma). The main chronic myeloproliferative disorders are: chronic myeloid (or myelogenous) leukemia (shown above), chronic (or idiopathic) myelofibrosis, polycythemia vera, and essential thrombocythemia. The main chronic lymphoproliferative disorders are: chronic lymphocytic leukemia, hairy cell leukemia, prolymphocytic leukemia, and large granulated lymphocyte leukemia.
I don’t know why they don’t just call the chronic myeloproliferative disorders and chronic lymphoproliferative disorders “chronic myeloid leukemias” and “chronic lymphoid leukemias,” but they don’t. Maybe it’s because one of the chronic myeloproliferative disorders is chronic myeloid leukemia, and to call the whole group of them “chronic myeloid leukemias” would be confusing. In fact, the term “chronic leukemia” isn’t really an official term either. But I like to use it because it shows that the chronic myeloproliferative and lymphoproliferative disorders really are leukemias, not some sort of benign proliferative disorders.
Thanks a lot. This was very satisfactory. The question was annoying me for long times.
I’m glad I could clear it up a bit!
This really helped clarify something that was bugging me for ages! Thank you
That was helpful.
Since having been diagnosed with ET, I have been reading a lot information about ET and other MPN’s. The above Q&A has cleared up some of my own questions. Thank you.
Thanks for clarifying this! The terminology is so confusing! Where does myeloma fit? I would’ve thought it’s a proliferative diseases given it involves proliferation of B cells? Is it different because it is predominantly a peripheral cell? although it does affect the marrow?
Good question! This post is about chronic MYELOproliferative disorders – myeloma is a proliferation of B cells, like you mentioned – so it’s a LYMPHoproliferative disorder. It is unusual, though, in that it’s not really a lymphoma (because it doesn’t involve lymph nodes) and it’s not really a leukemia either (it doesn’t leave the marrow or act like other leukemias). So it kind of is in its own category. Right now, the classification scheme for heme malignancies divides everything into lymphoid malignancies and myeloid malignancies – and myeloma is classified as a lymphoid malignancy. I hope that helps!
Thank you SO much!
Well explained! thank you â¤