MLPAO Hematology and Coagulation Advanced Practice 1 — Questions and Answers
Question 1: What is the significance of Auer rods found on a peripheral blood smear?
- They indicate viral infection
- They are pathognomonic for acute myeloid leukemia (Correct answer)
- They suggest iron overload
- They indicate vitamin B12 deficiency
Correct answer: They are pathognomonic for acute myeloid leukemia
Auer rods are needle-shaped, reddish-purple crystalline inclusions found in the cytoplasm of myeloid blast cells. They are pathognomonic (uniquely diagnostic) for acute myeloid leukemia and are never seen in acute lymphoblastic leukemia or benign conditions. Multiple Auer rods (faggot cells) are characteristic of acute promyelocytic leukemia (APL/M3).
Question 2: Which hematological malignancy is associated with the Philadelphia chromosome t(9;22)?
- Acute lymphoblastic leukemia
- Chronic myeloid leukemia (CML) (Correct answer)
- Hodgkin lymphoma
- Multiple myeloma
Correct answer: Chronic myeloid leukemia (CML)
The Philadelphia chromosome results from a translocation between chromosomes 9 and 22, creating the BCR-ABL1 fusion gene. This is the hallmark of chronic myeloid leukemia (CML) and is present in over 95% of CML cases. It is also found in some cases of ALL. Tyrosine kinase inhibitors (imatinib) target this abnormality.
Question 3: What is the principle of flow cytometry immunophenotyping in hematological malignancies?
- Measuring cell size by impedance
- Identifying cell surface and intracellular markers using fluorescent-labeled antibodies (Correct answer)
- Staining cells with Romanowsky dyes
- Counting cells based on nuclear morphology
Correct answer: Identifying cell surface and intracellular markers using fluorescent-labeled antibodies
Flow cytometry identifies cell types by using fluorescent-labeled monoclonal antibodies that bind to specific CD (cluster of differentiation) markers on cell surfaces or within cells. Cells pass through a laser beam in single file, and fluorescence patterns identify lineage (myeloid vs. lymphoid) and maturation stage.
Question 4: Which condition is characterized by a markedly elevated white blood cell count with a predominance of mature lymphocytes in an elderly patient?
- Acute myeloid leukemia
- Chronic lymphocytic leukemia (CLL) (Correct answer)
- Infectious mononucleosis
- Chronic myeloid leukemia
Correct answer: Chronic lymphocytic leukemia (CLL)
Chronic lymphocytic leukemia (CLL) is the most common leukemia in adults in Canada, typically presenting in patients over 60 years. It is characterized by a persistent lymphocytosis of mature-appearing small lymphocytes. Smudge cells (damaged fragile CLL cells) are characteristically seen on the blood smear.
Question 5: What is heparin-induced thrombocytopenia (HIT) type II?
- A benign, transient drop in platelets within the first 2 days of heparin
- An immune-mediated condition causing platelet activation, thrombocytopenia, and paradoxical thrombosis (Correct answer)
- An allergic reaction to heparin causing rash
- A genetic platelet disorder worsened by heparin
Correct answer: An immune-mediated condition causing platelet activation, thrombocytopenia, and paradoxical thrombosis
HIT type II is a serious immune-mediated condition where antibodies against heparin-platelet factor 4 (PF4) complexes activate platelets, causing both thrombocytopenia (platelet count drop >50%) and a paradoxical prothrombotic state. It typically occurs 5-14 days after heparin exposure and requires immediate heparin cessation and alternative anticoagulation.
Question 6: Which laboratory test is used to monitor direct oral anticoagulants (DOACs) when needed?
- PT/INR for all DOACs
- Anti-Xa assay for rivaroxaban/apixaban; dilute thrombin time for dabigatran (Correct answer)
- aPTT for all DOACs
- Fibrinogen assay
Correct answer: Anti-Xa assay for rivaroxaban/apixaban; dilute thrombin time for dabigatran
When DOAC levels need to be measured (emergency surgery, overdose, renal impairment), drug-specific calibrated assays are used. Anti-Xa assays calibrated with the specific drug measure rivaroxaban and apixaban levels. Dilute thrombin time or ecarin clotting time measures dabigatran levels.
MLPAO Hematology and Coagulation Advanced Practice 1
What is the significance of Auer rods found on a peripheral blood smear?