Leukemias Flashcards
Four Methodologies Used for Identifying & Classifying Leukemias
A. Morphologic review of bone marrow
B. Morphological review of peripheral blood smears
C. Cytochemical stains (Ex. → NSE, LAP, etc.)
D. Immunophenotyping
E. Cytogenetic & molecular analyses
“Supreme Court of Diagnosis”
Cytogenetic & molecular analyses
ALL
Acute lymphoblastic (less specifically, lymphocytic) Leukemia
CLL
Chronic lymphocytic leukemia:
AML
Acute myeloblastic (less specifically, Myelocytic or Myeloid) Leukemia; aka ANLL (Acute Nonlymphocytic Leukemia)
CML
Chronic myelocytic/Myelogenous/Myeloid Leukemia
Acute Myeloid (AML)
Myelocytic/Myelogenous
Promyelocytic
Monocytic
Myelomonocytic (AMML)
Erythrocytic (AEL)
Megakaryocytic (AMegL)
Acute Lymphoid (ALL)
T-Lymphocytic
B-Lymphocytic
Null Cell (?)
Chronic Myeloid
Myelocytic/
Myelogenous (CML)
Myelomonocytic (CMML)
Chronic Lymphoid
Lymphocytic (CLL)
Plasmacytic
Hairy Cell (HCL)
Prolymphocytic (PLL)
Hundreds of genetic defects now known to cause cancers. Usually somatic translocations and aneuploidy
Genetics
Chemicals causing bone marrow depression and aplasia predispose to leukemia later on (Ex. benzene, chloramphenicol, sulfa drugs, insecticides, antineoplastics)
Leukemogens
Some retroviruses transform N. cells by inserting their own oncogenes into host cells genome, causing them to become malignant. [EBV linked to Burkitt non-hodgkin lymphoma]
Viral infections
Transient, reactive leukocytosis due to infection
Temporary resemblance of peripheral blood picture to “leukemic picture”
Severe left shift & very rare nRBCs (WBCT > 50,000/uL)
Leukemoid reactions:
Presence of both nRBCs & left shift in peripheral blood
Caused by bone marrow damage from a malignant, “space-occuping lesion”, with consequent extensive extramedullary hematopoiesis
May be mild or severe, & occurs in CML & in lymphomas
Leukoerythroblastic reaction (aka. Leukoerythroblastic anemia, or Leukoerythroblastosis)
Presence of the BCR/ABL1 gene, or t(9;22), identifies CML
Leukemoid reaction vs Leukoerythroblastic reaction
Normal LAP scores
range from 15-170
LAP ↓ in early leukemia
(Ex → early CML) because leukemic neutrophils are too abnormal to express the LAP that normal mature bands & segs would
Lap ↑ in leukemoid reaction due to left shift
because there are tons of band & segs full of secondary granules containing LAP, just waiting to attack the infectious invaders – it only looks like leukemia because of the high WBC count.
Process of replacing active marrow by fat tissue during development; results in restrictive active marrow sites
Retrogression
- In patients with solid malignant tumors
- Example → lymphomas, carcinomas and sarcomas, with possible “mets” to bone marrow - As part of initial workup of unexplained ↑ or ↓ in RBCs, WBCs, and/or platelets
- As part of differential diagnosis workup for infections that manifest clinically as “fevers of unknown origin”
Three main reasons for performing a bone marrow evaluation
Posterior iliac crest (adults and children)
Sternum (adults)
Vertebrae (in adults)
Tibia (children <1 year old)
Four preferred locations for bone marrow tap (in order of preference):
- Developing hematopoietic cells (blasts of all types, normally at overall 5% cellularity)
- Macrophages or histiocytes: large cells, with abundant cytoplasm & debris-filled vacuoles, and irregular, “spreading” shape.
- Megakaryocytes: involved in platelet formation through endometriosis
- Osteoblasts: part of bone marrow stroma; specialized bone matrix-synthesizing cells
- Osteoclasts: huge (>100 u), multi-nucleated cells with ruffled border; formed from fusion of mono and macrophages!
Five types of normal bone marrow cells:
a. Positive in which AMLs? M1-M4
b. Positive cells show gray-black or red-brown cytoplasmic granules
c. Stain reacts w/ lysosomal enzyme primary granules of myeloid and (to lesser extent) of monocytic cells
d. Mature granulocytes give strongest (+) reaction; monos and immature granulocytes show less (+) (scattered pattern)
Myeloperoxidase (MPO or MPX)
Since _____ is NOT found in lymphoid cells, it is best used for differentiating between AML and ALL!
Myeloperoxidase (MPO or MPX)
a. stains lipoproteins and phospholipids
b. Found in primary (azurophilic) & secondary granules of mature and immature neutrophils (& in eos, & slightly in monos and monoblasts)
c. Negative for lymphs, megakaryocytes, and erythroid precursors
d. Results parallel those for MPO!
e. Positive in which AMLs? M1-M4
Sudan Black B (SBB)
This stain is also best for differentiating AML from ALL
Sudan Black B (SBB)
______ faster, but ____ more stable and can be run on older specimens
MPO, SBB
a. Pos in AMLs? → M1 - M4
b. Pos cells show reddish staining of cytoplasmic granules
c. Useful in separating monocyte precursors from granulocyte precursors
d. Present in 1° granules of neutrophils (& mast cells), but shows a negative or weak positive reaction in monocytes of lymphocytes
Specific Esterase
Auer rods of AML myelocytes strongly +1 why?
Because they’re fused 1° granules and contain SE (specific esterase)
____ (+) in monocytic cells, and T-cells
____ (-) in myeloid cells and megakaryocytes
Nonspecific Esterase (alpha-Napthyl Butyrate Esterase, NBE)
The NSEs primarily are used to differentiate _____ leukemias from monocytic ones!
Myeloid
More sensitive than NBE
Positive cells show brownish appearance
(NAE) Nonspecific esterase (Alpha-Napthyl acetate esterase, NAE)
____ strongly (+) in monocytes, T-cells, and megakaryocytes
NAE
“Fluoride inhibition” NaFl inhibits enzymatic activity in ______… other cells are unaffected
monocytes
____ stain is positive in these 4 disease states
80% ALL (chunky or block pattern)
CLL
Gaucher’s disease
Some AML (AMol, AEL, AMegL)
PAS
stains glycogen
Periodic Acid Schiff (PAS)
Used to diagnose Hairy cell Leukemia (HCL) because only these cells strongly + with this modified stain
TRAP stain
Add L-Tartaric acid, then stain. Normal cells will not retain acid phosphatase activity; however, HCL cells do retain this activity, because they have a different acid phosphatase isoenzyme: thus called “TRAP +”.
Acid phosphatase (ACP)
Positive cells show red ppt. With fast red violet stain; show black ppt. With fast blue violet stain
Leukocyte Alkaline Phosphatase (LAP)
a. Only neutrophils contain this enzyme (in varying amounts) in their secondary granules
b. Used to help differentiate early CML from other conditions like leukemoid reactions or PV (at a screening level only)
Leukocyte Alkaline Phosphatase (LAP)
Polycythemia vera
Leukemoid reaction
Bacterial infections
3rd trimester pregnancy
Steroid therapy
Chronic granulocytic leukemias
Blast crises
Chronic neutrophilic leukemias
CML w/ infectious
Myelofibrosis
Increased LAP (>110)
Late CML
CML in remission
Secondary erythrocytosis
Normal LAP
Early CML
PNH
Sideroblastic anemia
Marked eosinophilia
Sickle cell anemia
Improper technique
Myelodysplastic disorders
PNH
Viral infections
Decreased LAP <15
ACD
Hemochromatosis
Sideroblastic anemia
3 conditions with increased bone marrow [Fe]
Principle: Fe3+ (ferric) + potassium cyanide → ferricyanide (blue-green ppt.)
Used to evaluate RBC Fe stores; reported semi-quantitatively
(Perl’s) Prussian blue iron stain
T lymphoblasts and megakaryocytic precursors
Acid phosphatase stain
Mature neutrophils
Leukocyte alkaline phosphatase (LAP)
Granulocytes; slight in monos
Sudan Black B (SBB)
Abnormal blast cells
Periodic acid-schiff (PAS)
- Most common type of adult leukemia (incidence increases with age)
- All are rapidly fatal if left untreated
- Involves a defect of HSC (CD34+)
Acute Myeloid Leukemia
- Hyperuricemia due to increased cell turnover
- Hyperphosphatemia due to cell lysis
- Hypokalcemia due to progressive bone destruction
AML Lab Findings
These are all signs of tumor lysis syndrome- a group of metabolic complications that can occur in patients with a malignancy
abnormal hyperproliferation of bizarre granulocyte and/or monocyte precursors
Dysmyelopoiesis
- Makes up 5% of AMLs; found in children and adults younger than 60 yp
- WBCs have functional problems (With phago-cytosis and chemotaxis)
AML w/ t(8;21) (q22:q22)
- Blasts are large with abundant, dysplastic cytoplasm and numerous primary granules and Auer rods. Sometimes exhibit Pseudo-Pelger Huet
- MBO & SBB 1+
- PAS neg
- SE +
- (+/-) Auer rods
AML w/ t(8;21) (q22:q22)
- Rare: 5-8% of all AMLs and occurs at any age (usually young)
- Myeloblasts, monoblasts, and promyelocytes observed
- Also eosinophilia with dysplastic changed
Remission rate is good but only ½ are cured
AML w/ inv(16)(p13.1p22)
- Makes up 8% of AMLs
- Abnormal hypergranular promyelocytes with Auer rods
- Granules can obscure nucleus with abundant cytoplasm and variable nucleus size and shape
AML w/ t(15;17) (q22;q12)- Acute promyelocytic leukemia (APL)
Leukemic cells also have defective retinoic acid receptor (RARa gene), so can be treated with ____
ATRA (All Trans Retinoic Acid – Vit A derivitive
ATRA pushes ____ into finishing maturation, thus causing remission!
Pros
Unusual susceptibility to bleeding (hemorrhage) due to a defect in the system of coagulation
“bleeding diathesis”
- Strongly associated with DIC
- A promyelocytes primary granules are rich in thromboplastin-like substances… which trigger a “bleeding diathesis”
Acute promyelocytic leukemia (APL)
cells look agranular if only light microscopy used – what subtype of leukemia is this?
Microgranular APL
bundles of auer rods
faggot cells in Acute Promyelocytic Leukemia
- Prolonged clotting time tests
- ⬇ plt. Count (because plts. Used up making clots)
- MPO and SBB= 2+ pos.
- PAS neg
- SE pos
- Both NSEs neg
- auer rods, can be in bundles
Lab findings of APL
Peripheral blood absolute monocytosis (>20%); many circulating blasts, pros, immature granulocytes and monos!
Acute myelomonocytic leukemia (aka. AMML)
- MBO and SBB still +
- Both NSEs now start to be +
- SE still +
- PAS still (-)
- (+/-) Auer rods
- CD 11b, CD 4, CD 36, and CD 64
Acute myelomonocytic leukemia (aka. AMML)
CND and soft tissue involvement
Ex. gum hypertrophy and skin lesions
AMML – Acute myelomonocytic leukemia
Usually CD4 and CD64 pos (“gold std.”)
Acute monocytic leukemia (aka. AMoL)
Makes up 5-8% of AMLs
When >80% leukemic cells are monocytic
Acute monocytic leukemia (aka. AMoL)
Bone marrow shows some granulocytes, but majority composition is monoblasts, promonocytes, and monocytes
Acute monocytic leukemia (aka. AMoL)
Increased serum and urinary lysozyme - why?
Because this is enzyme found in greatest amounts in monos
- MPO and SBB +/- (most frequently NEG)
- Both NSEs pos (NBE 3+!)
- PAS pos (finally)
- Very rare Auer rods (most frequently NEG)
Acute Monocytic leukemia - AMoL
Makes up only 3% of AMLs
Only AML with marked erythroid precursor hyperplasia
Acute erythroid leukemia (AEL)
Leukemia that is frequently preceded by a myelodysplastic syndrome
Acute erythroid leukemia (AEL)
abnormal proliferation of bizarre RBC precursors, with reverse M:E ratio due to huge # of abnormal erythroblasts, and even a few ringed sideroblasts
dyserythropoiesis
- Bone marrow shows dyserythropoiesis
- Peripheral blood- nRBCs with marked aniso, poikilocytosis and schistocytosis due to the dyserythropoiesis
- Lots of myeloblasts
Acute Erythroid Leukemia
- > 50% bizarre, multinucleated, megaloblastoid nRBCs!! (with few ringed sideroblasts)
- Both NSEs+
- PAS +
Acute erythroid leukemia
Early, abnormal erythroblasts are PAS + in “______” or “blocky” pattern. Later, abnormal erythroblasts + in “_____” pattern
Granular; diffuse