MT 214 Lesson 3: Acute Leukemia

Vocabulary flashcards covering the definitions, classifications (FAB and WHO), cytochemistry, and markers for Acute Myeloid Leukemia (AML) and Acute Lymphoid Leukemia (ALL) according to the MT 214 lecture notes.

Leukemia

A group of malignant (neoplastic) disorders characterized by the clonal expansion and accumulation of one or more blood cell lines, involving hematopoietic and other organs.

Myeloperoxidase (MPO)

A cytochemical stain for neutrophil primary granules; myeloblasts are strong positive, monoblasts are faint positive, and lymphoblasts are negative.

Sudan Black B (SBB)

A cytochemical stain for phospholipids; myeloblasts are strong positive and lymphoblasts are negative.

Specific esterase

A cellular enzyme that yields a positive reaction at the promyelocyte stage.

Nonspecific esterase (NSE)

A cellular enzyme for which monoblasts are strong positive, while other cells are usually negative.

Periodic acid-schiff (PAS)

A stain for glycogen and related substances; lymphoblasts and pronormoblasts range from negative to positive, while myeloblasts are usually negative.

Myeloid Markers

$CD13$ and $CD33$ represent these specific lineage markers during immunophenotyping.

Immature Markers

$CD34$, $CD117$, and HLA-DR are markers indicating this stage of cell development.

Monocytic Markers

$CD11b$, $CD14$, $CD4$, and $CD64$ are used to identify this blood cell lineage.

Acute Myeloid Leukemia (AML)

Also known as acute myelogenous leukemia or acute nonlymphocytic leukemia (ANLL); it is the most common acute leukemia affecting adults.

Differentiation arrest

A pathophysiological process where genetic changes "freeze" a cell in its immature state and prevent it from maturing.

Gum hypertrophy

A clinical physical finding specifically associated with monocytic types of AML (M4 and M5).

Leukemia cutis

A physical finding of leukemia involving the skin.

AML M0

Acute myeloblastic leukemia with minimal differentiation; accounts for $5\%$ of AML cases and is most common in adults.

AML M1

Acute myeloblastic leukemia without maturation; characterized by a predominance of myeloblasts ($> 90\%$) with less than $10\%$ maturation.

AML M2

Acute myeloblastic leukemia with maturation; the most frequent subtype ($30-45\%$ of cases), often associated with $t(8;21)$, AML1::ETO.

Acute Promyelocytic Leukemia (APML or AML M3)

Subtype associated with $t(15;17)$, hemorrhagic manifestation secondary to DIC, and "faggot cells" containing bundles of Auer rods.

Auer rods

Needle-like cytoplasmic inclusions found in myeloblasts and promyelocytes; bundles of these are called "faggots."

Acute Myelomonocytic Leukemia (AML M4)

Characterized by both neutrophilic and monocytic cells ($\ge 20\%$ each in marrow) and elevated levels of muramidase (lysozyme).

Muramidase

Also called lysozyme; serum and urine levels of this enzyme are elevated in monocytic proliferations (M4 and M5).

Acute Erythroid Leukemias (AML M6)

Includes M6a (Erythroleukemia) and M6b (Pure erythroid leukemia or Di Guglielmo syndrome), characterized by dyserythropoiesis and coarse PAS positivity.

Acute Megakaryoblastic Leukemia (AML M7)

A rare subtype where $\ge 50\%$ of blasts are megakaryocytic; characterized by cytoplasmic blebs or pseudopods.

Induction Chemotherapy

The initial treatment phase for AML typically using the "$3+7$" protocol: Anthracycline (Idarubicin) for 3 days and Cytosine arabinoside (Ara-C) for 7 days.

ATRA (All-trans retinoic acid)

A derivative of Vitamin A used to treat AML-M3 (APL) by blocking the effect of the retinoic acid receptor-alpha gene translocation.

Acute Lymphoid Leukemia (ALL)

Malignant neoplastic proliferation of immature lymphoid cells; the most common type of cancer in children.

Terminal Deoxynucleotidyl transferase (TdT)

A DNA polymerase found in lymphoblasts; used to distinguish ALL (positive) from mature B-cell malignancies (negative).

CALLA

The Common Acute Lymphoblastic Leukemia Antigen, also known as $CD10$.

ALL-L1

FAB classification for ALL primarily affecting children; characterized by small blasts, high N/C ratio, and scant cytoplasm.

ALL-L2

FAB classification for ALL primarily affecting adults; characterized by larger, pleomorphic blasts with nuclear clefting.

ALL-L3 (Burkitt’s type)

FAB classification characterized by large, homogenous blasts with strong basophilic cytoplasm and lipid cytoplasmic vacuolation.

Philadelphia chromosome ($Ph+$)

A $t(9;22)$ bcr/abl translocation in B-ALL associated with increasing incidence with age and a very poor outcome.

Myeloid sarcoma

A tumor of myeloblasts or immature myeloid cells occurring in extramedullary sites or in the bone.