Hematopoietic Neoplasms: Foundations & Frameworks

What are hematopoietic neoplasms?

Disorders arising from hematopoietic stem cells in the bone marrow that produce abnormal blood cells.

Where do hematopoietic neoplasms originate?

Primordial hematopoietic stem cells (HSCs) in bone marrow.

What normal cells arise from hematopoietic stem cells?

RBCs, WBCs, and platelets.

What are the main categories of hematopoietic neoplasms?

Leukemia, lymphoma, and multiple myeloma.

What are the two main stem cell lines?

Myeloid and lymphoid cell lines.

What does the myeloid line produce?

Erythrocytes, granulocytes, monocytes, and platelets.

What does the lymphoid line produce?

Lymphocytes (B cells, T cells, NK cells).

What is the WHO classification based on?

Cell of origin: myeloid vs lymphoid.

Why does WHO use “neoplasm” instead of “malignancy”?

Some disorders proliferate abnormally but are not fully malignant.

What is a key effect of non-malignant neoplasms?

Crowding out normal bone marrow cells.

What are the three categories of myeloid neoplasms?

Myeloproliferative neoplasms, myelodysplastic neoplasms, and acute myeloid leukemia (AML).

What characterizes myeloproliferative neoplasms?

Overproduction of one or more myeloid cell lines in bone marrow.

What happens to normal cells in myeloproliferative neoplasms?

They are overwhelmed and reduced in number.

What is polycythemia vera?

Myeloproliferative disorder with dominant increase in RBCs.

What is chronic myeloid leukemia (CML)?

Myeloproliferative disorder with granulocyte dominance.

What is essential thrombocythemia?

Myeloproliferative disorder with platelet overproduction.

What is primary myelofibrosis?

Marrow fibrosis replacing hematopoietic tissue.

What characterizes myelodysplastic neoplasms?

Dysplastic precursor cells causing ineffective hematopoiesis.

What is a key consequence of myelodysplastic neoplasms?

Bone marrow failure and cytopenias.

What percentage of MDS progresses to AML?

Approximately 30 percent.

What defines acute myeloid leukemia (AML)?

Malignant proliferation of myeloid blasts filling bone marrow.

What is a key complication of AML?

Pancytopenia due to marrow failure.

Why are infections common in AML?

Reduced number and function of WBCs.

What are the three categories of lymphoid neoplasms?

T-cell neoplasms, B-cell neoplasms, and Hodgkin lymphoma.

What defines precursor lymphoid neoplasms?

Arise from immature cells in bone marrow.

What defines mature lymphoid neoplasms?

Arise from differentiated lymphocytes in tissues or nodes.

What is ALL?

Acute lymphoblastic leukemia/lymphoma from precursor lymphoid cells.

Why is ALL called leukemia/lymphoma?

It can present with both marrow and lymph node involvement.

What population is most affected by ALL?

Children; it is the most common childhood cancer.

What is the difference between T-cell and B-cell ALL?

T-cell has worse prognosis and different clinical features.

What are mature T-cell neoplasms?

Lymphomas arising from peripheral T cells, such as mycosis fungoides.

What is a hallmark of mycosis fungoides?

Slow-growing skin lesions progressing to tumors.

What is unique about mycosis fungoides prognosis?

Indolent with near-normal life expectancy.

What defines B-cell neoplasms?

Lymphoid neoplasms derived from B lymphocytes.

What are precursor B-cell neoplasms?

B-cell acute lymphoblastic leukemia/lymphoma.

What are mature B-cell neoplasms?

Non-Hodgkin lymphomas and plasma cell neoplasms.

What are examples of low-grade NHL?

CLL/SLL, follicular lymphoma, MALT lymphoma, hairy cell leukemia.

What characterizes low-grade NHL?

Slow growth and good prognosis.

What are examples of high-grade NHL?

Burkitt lymphoma and diffuse large B-cell lymphoma.

What characterizes high-grade NHL?

Rapid growth and high mortality if untreated.

What are common symptoms of NHL?

Lymphadenopathy, weight loss, fever, fatigue.

What distinguishes lymphoma from leukemia clinically?

Lymphomas cause lymphadenopathy; leukemias alter blood counts.

Where do leukemias originate?

Bone marrow.

Can leukemias involve lymph nodes?

Yes, as disease progresses.

Can lymphomas involve bone marrow or blood?

Yes, in advanced stages.

What defines acute leukemia?

Immature precursor cells with rapid progression.

What defines chronic leukemia?

Mature cells with slower progression.

What is the most important WHO distinction in neoplasms?

Myeloid vs lymphoid origin.

What is Hodgkin lymphoma defined by?

Presence of Reed-Sternberg cells.

What is the morphology of Reed-Sternberg cells?

Large cells with bilobed “owl-eye” nuclei.

Why is Hodgkin lymphoma classified separately?

Loss of typical B-cell marker expression despite B-cell origin.

What is the typical age distribution of Hodgkin lymphoma?

Young adults and older adults.

What is the prognosis of Hodgkin lymphoma compared to NHL?

Generally better prognosis.

What is the key clinical takeaway of hematopoietic neoplasms?

Classified by cell origin, with overlapping features between leukemia and lymphoma.