Hematopathology Practice Questions

Q: Which of the following statements regarding G6PD deficiency is true?

It is associated with bite cells.. **Explanation:** **Glucose-6-Phosphate Dehydrogenase (G6PD) deficiency** is the most common red cell enzyme defect worldwide. It results in an inability to maintain adequate levels of reduced glutathione, leaving hemoglobin vulnerable to oxidative stress. **1. Why Option B is correct:** When RBCs are exposed to oxidative stress (e.g., fava beans, infections, or drugs like Primaquine), hemoglobin denatures and precipitates into **Heinz bodies**. As these cells pass through the splenic sinusoids, splenic macrophages "pluck out" these inclusions. This process removes a portion of the red cell membrane, resulting in characteristic **"Bite cells" (Degmacytes)**. If the cell remains in circulation, it may appear as a **Blister cell**. **2. Why other options are incorrect:** * **Option A:** G6PD deficiency is an **X-linked recessive** condition, primarily affecting males. * **Option C:** It provides a survival advantage against **Malaria** (*Plasmodium falciparum*), not Kala-azar. The oxidative stress inhibits the optimal growth of the parasite within the RBC. * **Option D:** Enzyme levels are **inversely proportional** to the age of RBCs. Reticulocytes and young RBCs have the highest enzyme activity, while older cells are most deficient. This is why G6PD levels may appear falsely normal during an acute hemolytic episode (as older cells have been destroyed). **High-Yield Clinical Pearls for NEET-PG:** * **Diagnosis:** Best initial test is a peripheral smear (Bite cells); Gold standard is the **Quantitative spectrophotometric assay** (performed 6–8 weeks after a hemolytic crisis). * **Common Triggers:** Sulfa drugs, Nitrofurantoin, Primaquine, Naphthalene balls, and Fava beans. * **Inheritance:** X-linked recessive (Lyon’s hypothesis explains rare symptomatic females).

Q: Pseudothrombocytopenia is due to platelet agglutination antibodies when the calcium content is decreased by blood EDTA. The antibody responsible for this effect is mainly:

IgG. **Explanation:** **Pseudothrombocytopenia (PTCP)** is an *in vitro* laboratory artifact where the automated platelet count is falsely low. This occurs due to platelet clumping (agglutination) in blood samples collected in **EDTA-anticoagulated tubes**. **1. Why IgG is the correct answer:** The phenomenon is mediated by **naturally occurring autoantibodies**, which are almost always of the **IgG class** (though IgM is rarely implicated). These antibodies are "cryptic," meaning they only recognize and bind to the **GP IIb/IIIa receptor** on the platelet surface when its conformation is altered. EDTA acts as a chelating agent that decreases ionized calcium; this reduction in calcium causes a structural change in the GP IIb/IIIa complex, exposing the hidden epitopes. The IgG antibodies then bind to these sites, causing platelets to agglutinate, which the automated counter misidentifies as single large particles or leukocytes. **2. Why other options are incorrect:** * **IgA and IgD:** These immunoglobulins are not associated with the cold-reacting autoantibody mechanism involved in EDTA-induced clumping. * **IgM:** While IgM can occasionally be involved in cold agglutinin diseases, the specific EDTA-dependent mechanism that targets the GP IIb/IIIa complex is predominantly mediated by IgG. **Clinical Pearls for NEET-PG:** * **Diagnosis:** Suspect PTCP if the patient has a low platelet count but **no clinical signs of bleeding** (petechiae/purpura). * **Confirmation:** Examine a **peripheral blood smear** to visualize platelet clumps. * **Management:** Repeat the test using a different anticoagulant, such as **Sodium Citrate (blue top)** or Heparin, or perform a manual count immediately after collection. * **Key Association:** It is a purely *in vitro* phenomenon with no clinical significance for the patient's actual hemostatic status.

Q: A patient has normal prothrombin time (PT) and platelet count. The activated partial thromboplastin time (aPTT) is increased, and factor VIII levels are observed to be 60% (normal). There is no associated history of bleeding even after a surgical procedure. What is the most likely diagnosis?

Lupus anticoagulant. The clinical scenario describes an **isolated prolonged aPTT** with a normal PT, normal platelet count, and normal Factor VIII levels (60% is within the low-normal range). The most critical clue is the **absence of bleeding**, even after surgical stress. **1. Why Lupus Anticoagulant (LA) is correct:** Lupus anticoagulant is an antiphospholipid antibody. In *vitro* (in the lab), these antibodies interfere with the phospholipids used in the aPTT reagent, causing a paradoxical prolongation of the clotting time [1]. However, in *vivo* (in the body), LA is **pro-thrombotic**, not pro-hemorrhagic. Therefore, patients do not bleed; instead, they are at risk for arterial and venous thrombosis. This "asymptomatic prolongation of aPTT" is a classic board exam presentation for LA. **2. Why other options are incorrect:** * **Factor IX deficiency (Hemophilia B):** This would cause a prolonged aPTT, but it is characterized by a significant **bleeding tendency** (hemarthrosis, post-surgical bleeding). * **Factor VIII inhibitors:** These are antibodies against Factor VIII. They cause a prolonged aPTT and **severe bleeding** manifestations [1]. Furthermore, Factor VIII levels would be significantly low, not 60%. * **Thalassemia:** This is a hemoglobinopathy affecting red blood cells. It does not affect the coagulation cascade, PT, or aPTT. **Clinical Pearls for NEET-PG:** * **Mixing Study:** If aPTT remains prolonged after mixing the patient's plasma with normal plasma (1:1), it indicates the presence of an **inhibitor** (like LA) rather than a factor deficiency [1]. * **The "Silent" Prolonged aPTT:** Always consider **Factor XII deficiency** or **Lupus Anticoagulant** when aPTT is high but the patient has no bleeding symptoms. * **Paradox:** LA causes a "long aPTT" in the lab but "clots" in the patient.

Question 1

Which of the following statements regarding G6PD deficiency is true?

Accepted Answer

It is associated with bite cells.

Answer

It is an autosomal dominant condition.

Answer

It protects against kala azar.

Answer

Enzyme levels are directly proportional to the age of RBCs.

Question 2

Pseudothrombocytopenia is due to platelet agglutination antibodies when the calcium content is decreased by blood EDTA. The antibody responsible for this effect is mainly:

Accepted Answer

IgG

Answer

IgA

Answer

IgM

Answer

IgD

Question 3

Overexpression of BCL-2 proteins occurs in which of the following conditions?

Accepted Answer

Follicular lymphoma

Answer

Burkitt's lymphoma

Answer

Diffuse large B-cell lymphoma

Answer

AML

Question 4

A patient has normal prothrombin time (PT) and platelet count. The activated partial thromboplastin time (aPTT) is increased, and factor VIII levels are observed to be 60% (normal). There is no associated history of bleeding even after a surgical procedure. What is the most likely diagnosis?

Accepted Answer

Lupus anticoagulant

Answer

Factor IX deficiency

Answer

Factor VIII inhibitors

Answer

Thalassemia

Question 5

Which lymphoid malignancy arises from thymic cells?

Accepted Answer

Pre-T cell ALL

Answer

Hairy cell leukemia

Answer

Burkitt lymphoma

Answer

Pre-B cell ALL

Question 6

All of the following are good prognostic factors for acute lymphoblastic leukemia except?

Accepted Answer

+ (9;22), + (8;14)

Answer

Age of onset between 2-8 years

Answer

Hyperdiploidy, trisomy of chromosomes 4, 7 and 10 and + (12;21)

Answer

Initial WBC count less than 50000

Question 7

A student presents for evaluation of anemia. His RDW was observed to be 13.5 while the MCV was 62.5 fl. What is the likely diagnosis?

Accepted Answer

Anemia of chronic disease

Answer

Hemoglobin D Punjab (HB-D Trait)

Answer

Thalassemia Major

Answer

Iron Deficiency Anemia

Question 8

Which of the following features is characteristic of megaloblastic anemia?

Accepted Answer

Megaloblastic anemia

Answer

Aplastic anemia

Answer

Iron deficiency anemia

Answer

Leukemia

Question 9

Which of the following is NOT typically seen in multiple myeloma?

Accepted Answer

Anion gap raised

Answer

Lytic bone lesion

Answer

Polyarticular pains

Answer

M spike present with polyarticulopathy

Question 10

Which of the following is an immune response cause of anemia?

Accepted Answer

Hemolytic disease of the newborn

Answer

Diamond Blackfan anemia

Answer

Hereditary spherocytosis

Answer

Glucose-6-phosphate dehydrogenase deficiency

Hematopathology — MCQs

Hematopathology — MCQs

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