Diseases of Hematopoietic Cells & Lymph Nodes – Core Vocabulary

Vocabulary flashcards covering key people, cells, processes, disorders, mutations, and laboratory terms central to hematology and lymphoid pathology.

Hematology

Branch of medicine that studies blood, blood-forming organs, and blood disorders.

William Hewson

18th-century British surgeon called the “father of hematology”; described coagulation and first isolated fibrinogen (coagulable lymph).

Maxwell Myer Wintrobe

20th-century hematologist; created the Wintrobe hematocrit tube and wrote the first clinical hematology textbook.

Hematopoietic Stem Cell (HSC)

Multipotent cell in bone marrow that gives rise to all blood cell lineages.

Myeloid Lineage

Hematopoietic branch producing granulocytes, monocytes, erythrocytes, and megakaryocytes; common mutations FLT3, RUNX1, NPM1, JAK2.

Lymphoid Lineage

Hematopoietic branch generating B, T, and NK cells; common mutations NOTCH1, BCL2, BCL6, MYC, IgH translocation.

Bone Marrow

Primary site of hematopoiesis housed in bone cavities; contains red (active) and yellow (fatty, inactive) marrow.

Red Marrow

Active, hematopoietic marrow rich in HSCs; predominant at birth.

Yellow Marrow

Inactive marrow containing abundant fat; increases with age.

Mesenchymal Stem Cell (MSC)

Stromal bone-marrow cell that can differentiate into bone, cartilage, and fat cells and supports hematopoiesis.

Sinusoidal Network

System of vascular channels in marrow through which mature blood cells enter circulation.

Hematopoiesis

Process by which all blood cells are formed from HSCs under influence of growth factors such as SCF, Epo, GM-CSF.

Stem Cell Factor (SCF)

Cytokine essential for survival and proliferation of hematopoietic stem cells.

Erythropoietin (Epo)

Kidney-derived hormone that stimulates red blood cell production.

Thrombopoietin (TPO)

Hormone that promotes megakaryocyte maturation and platelet production.

GM-CSF

Granulocyte-macrophage colony-stimulating factor; drives production of neutrophils and monocytes.

G-CSF

Granulocyte colony-stimulating factor; specifically boosts neutrophil production.

M-CSF

Macrophage colony-stimulating factor; promotes monocyte/macrophage lineage growth.

Leukopenia

Abnormally low white blood cell count.

Leukocytosis

Elevated white blood cell count, often reactive to infection or inflammation.

Neutropenia

Decrease in circulating neutrophils; predisposes to bacterial/fungal infections.

Agranulocytosis

Severe neutropenia causing high risk of fulminant infection; commonly drug-induced.

Smudge Cell

Fragile, ruptured lymphocyte seen on smear in chronic lymphocytic leukemia.

Auer Rod

Azurophilic needle-like inclusion in myeloblasts characteristic of AML.

Blast

Immature precursor cell; excess (>20% in marrow) defines acute leukemia.

Acute Lymphoblastic Leukemia (ALL)

Aggressive childhood leukemia of precursor B or T cells; involves NOTCH1, PAX5, ETV6-RUNX1 lesions.

Chronic Lymphocytic Leukemia (CLL)

Indolent adult leukemia of mature CD5+, CD23+ B cells; shows smudge cells and may evolve to Richter syndrome.

Acute Myeloid Leukemia (AML)

Aggressive myeloid blast tumor (>20% blasts); Auer rods, myeloperoxidase+; APML subtype t(15;17) responds to ATRA.

Chronic Myeloid Leukemia (CML)

Myeloproliferative neoplasm with BCR-ABL1 fusion (Philadelphia chromosome); treated with tyrosine-kinase inhibitors.

Lymphadenitis

Inflammatory enlargement of lymph nodes; may be acute or chronic.

Hemophagocytic Lymphohistiocytosis (HLH)

Severe systemic inflammation with macrophage activation, cytopenias, high ferritin; often EBV-related.

Lymphoma

Malignancy of lymphoid tissues forming mass lesions; divided into Hodgkin and Non-Hodgkin types.

Hodgkin Lymphoma

Lymphoma marked by Reed-Sternberg cells, usually contiguous node spread; often EBV-associated.

Reed-Sternberg Cell

Binucleate giant B cell pathognomonic for classical Hodgkin lymphoma.

Non-Hodgkin Lymphoma (NHL)

Heterogeneous group of mostly B-cell (some T-cell) lymphomas with noncontiguous spread.

Follicular Lymphoma

Indolent B-cell NHL with nodular pattern and t(14;18) BCL2 overexpression.

Diffuse Large B-cell Lymphoma (DLBCL)

Most common aggressive NHL; large cells, BCL6/BCL2/MYC alterations; potentially curable.

Burkitt Lymphoma

Highly aggressive B-cell tumor with MYC t(8;14), “starry-sky” histology; endemic jaw or sporadic abdominal forms.

Multiple Myeloma

Malignant plasma-cell neoplasm producing M protein; causes lytic bone lesions, hypercalcemia, renal failure.

Bence Jones Protein

Free monoclonal light chains in urine indicative of multiple myeloma.

Rouleaux Formation

Stacking of red cells on smear due to high immunoglobulin levels, classically in myeloma.

Anemia

Decrease in red cell mass or hemoglobin, leading to reduced oxygen-carrying capacity.

Reticulocytosis

Elevated young red cells in blood, reflecting increased erythropoiesis.

Hemosiderosis

Iron overload with deposition of hemosiderin in organs, often after chronic hemolysis.

Sickle Cell Anemia

Inherited hemolytic anemia from HbS mutation causing red cell sickling and vaso-occlusion.

Hemoglobin S

Abnormal beta-globin variant responsible for sickling of RBCs in sickle cell disease.

Vaso-occlusive Crisis

Painful ischemic episode in sickle cell disease due to microvascular blockage by sickled cells.

Hemophilia

Inherited deficiency of clotting factors VIII (A), IX (B), or XI (C) leading to prolonged bleeding.

Factor VIII

Intrinsic pathway clotting protein deficient in Hemophilia A.

Thrombocytopenia

Platelet count <150,000/µL; raises bleeding risk; may be immune, drug-induced, or marrow-related.

Immune Thrombocytopenic Purpura (ITP)

Autoimmune destruction of platelets causing isolated thrombocytopenia and mucocutaneous bleeding.

Disseminated Intravascular Coagulation (DIC)

Systemic activation of coagulation leading to microthrombi and consumptive bleeding; triggered by sepsis, trauma, obstetric events.

Thrombocytosis

Platelet count >450,000/µL; may be reactive or clonal (essential thrombocythemia).

Essential Thrombocythemia (ET)

Myeloproliferative neoplasm with sustained platelet overproduction; often JAK2 or CALR mutated.

JAK2 Mutation

Gain-of-function alteration activating cytokine signaling, common in ET and other MPNs.

BCL2

Anti-apoptotic gene overexpressed in follicular lymphoma via t(14;18) translocation.

BCL6

Transcription regulator frequently rearranged in DLBCL.

MYC Translocation

t(8;14) or variants driving Burkitt lymphoma via overexpression of MYC oncogene.

ATRA (All-trans Retinoic Acid)

Differentiation therapy used in acute promyelocytic leukemia with t(15;17).

NOTCH1

Signaling gene mutated in T-cell ALL.

PAX5

B-cell transcription factor commonly altered in B-cell ALL.

ETV6-RUNX1

Fusion gene from t(12;21) associated with favorable-risk childhood B-ALL.

FLT3

Receptor tyrosine kinase frequently mutated in AML and other myeloid neoplasms.