Hematopathology Practice Questions

Q: Leukocyte common antigen (CD45) is typically seen in which of the following malignancies?

Lymphoma. **Explanation:** **Leukocyte Common Antigen (CD45)** is a transmembrane glycoprotein found on the surface of almost all **hematopoietic cells** and their precursors [1]. It is the most widely used Immunohistochemistry (IHC) marker to differentiate hematopoietic malignancies from non-hematopoietic tumors (small round blue cell tumors). 1. **Why Lymphoma is Correct:** Lymphomas are malignancies of lymphoid lineage. Since CD45 is expressed on all leukocytes (B-cells, T-cells, NK-cells, and granulocytes), it serves as a **pan-leukocyte marker**. Almost all Non-Hodgkin Lymphomas (NHL) are CD45 positive, making it the primary marker for confirming a lymphoid origin in undifferentiated tumors. 2. **Why Other Options are Incorrect:** * **Ewing Sarcoma:** This is a neuroectodermal tumor characterized by the **CD99 (MIC2)** marker. It is CD45 negative. * **Rhabdomyosarcoma:** A skeletal muscle tumor identified by markers like **Desmin, Myogenin, and MyoD1**. It is CD45 negative. * **Osteosarcoma:** A bone-forming tumor that expresses markers like **SATB2** and Osteonectin. It is CD45 negative. **High-Yield Clinical Pearls for NEET-PG:** * **CD45 Exceptions:** While most lymphomas are CD45+, **Classic Hodgkin Lymphoma (RS cells)** is characteristically **CD45 negative** (but CD15+ and CD30+). * **Small Round Blue Cell Tumors (SRBCT):** In a pediatric patient with an undifferentiated SRBCT, the first step in IHC is usually CD45. If positive, it suggests Lymphoma; if negative, other markers like CD99 (Ewing’s) or Desmin (RMS) are evaluated. * **Lineage Specificity:** CD45 confirms the cell is a leukocyte, but further markers (CD3 for T-cells, CD20 for B-cells) are needed to sub-classify the lymphoma [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of White Blood Cells, Lymph Nodes, Spleen, and Thymus, pp. 596-598.

Q: Haemophilia B is due to a mutation in the gene corresponding to which coagulation factor?

Factor 9. **Explanation:** Hemophilia is a group of hereditary genetic disorders that impair the body's ability to control blood clotting. **Hemophilia B**, also known as **Christmas Disease**, is caused by a deficiency or mutation in the gene encoding **Coagulation Factor IX (9)**. It is inherited as an **X-linked recessive** trait, primarily affecting males [1]. **Analysis of Options:** * **Factor 9 (Correct):** Deficiency leads to Hemophilia B [1]. Factor IX is a serine protease that, when activated (IXa), forms a complex with Factor VIIIa to activate Factor X in the intrinsic pathway. * **Factor 8 (Incorrect):** Deficiency of Factor VIII causes **Hemophilia A** (Classic Hemophilia) [1]. It is the most common type of hemophilia (80-85% of cases). * **Factor 11 (Incorrect):** Deficiency leads to **Hemophilia C** (Rosenthal Syndrome). Unlike A and B, it is autosomal recessive and often seen in Ashkenazi Jews. * **Factor 7 (Incorrect):** Deficiency causes a rare autosomal recessive bleeding disorder. Factor VII is part of the extrinsic pathway (measured by PT/INR). **High-Yield Clinical Pearls for NEET-PG:** * **Inheritance:** Both Hemophilia A and B are **X-linked recessive** [1]. * **Lab Findings:** Characterized by a **prolonged aPTT** with a **normal PT** and **normal bleeding time** (platelet function is unaffected). * **Clinical Presentation:** Hallmark is **Hemarthrosis** (bleeding into joints, most commonly the knee) and deep muscle hematomas. * **Treatment:** Factor replacement therapy is the mainstay. For Hemophilia B, recombinant Factor IX is used. Unlike Hemophilia A, Desmopressin (dDAVP) is **not** effective for Hemophilia B.

Q: What is the chromosomal abnormality seen in promyelocytic leukemia?

t(15;17). **Explanation:** **Acute Promyelocytic Leukemia (APL)**, classified as AML-M3 in the FAB system, is characterized by the pathognomonic balanced reciprocal translocation **t(15;17)(q22;q12)** [1]. 1. **Mechanism of Correct Answer (A):** This translocation involves the fusion of the **PML** (Promyelocytic Leukemia) gene on chromosome 15 and the **RARα** (Retinoic Acid Receptor alpha) gene on chromosome 17 [1]. The resulting **PML-RARα fusion protein** acts as a dominant-negative repressor, blocking myeloid differentiation at the promyelocyte stage [2]. High doses of All-Trans Retinoic Acid (ATRA) can overcome this block, inducing the maturation of leukemic cells [2]. 2. **Analysis of Incorrect Options:** * **t(9;21):** This is not a standard recognized translocation in common leukemias. (Note: t(8;21) is associated with AML-M2). * **t(9;22):** Known as the **Philadelphia chromosome**, this is the hallmark of **Chronic Myeloid Leukemia (CML)** and is also seen in a subset of B-ALL (poor prognosis). It involves the BCR-ABL1 fusion. 3. **High-Yield Clinical Pearls for NEET-PG:** * **Morphology:** Presence of **Auer rods** (often in bundles called **Faggot cells**) [1]. * **Complication:** High risk of **Disseminated Intravascular Coagulation (DIC)** due to the release of procoagulants from primary granules. * **Treatment:** ATRA and Arsenic Trioxide (ATO) [2]. * **Cytogenetics:** Essential for diagnosis; FISH or RT-PCR can detect the PML-RARα transcript. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of White Blood Cells, Lymph Nodes, Spleen, and Thymus, pp. 620-621. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, p. 326.

Question 1

Glanzmann thrombasthenia is due to a defect in which of the following?

Accepted Answer

Glycoprotein IIb/IIIa complex

Answer

Glycoprotein Ib-IX complex

Answer

CD68

Answer

Von Willebrand factor

Question 2

Spur cell anemia is seen in which of the following conditions?

Accepted Answer

Hepatocellular disease

Answer

Drug-induced anemia

Answer

Renal disease

Answer

Alcoholism

Question 3

Hallmark cells are characteristic findings in which of the following hematological malignancies?

Accepted Answer

Anaplastic large-cell lymphoma

Answer

Diffuse large B-cell lymphoma

Answer

Hodgkin lymphoma

Answer

Hairy cell leukemia

Question 4

Leukocyte common antigen (CD45) is typically seen in which of the following malignancies?

Accepted Answer

Lymphoma

Answer

Ewing sarcoma

Answer

Rhabdomyosarcoma

Answer

Osteosarcoma

Question 5

Haemophilia B is due to a mutation in the gene corresponding to which coagulation factor?

Accepted Answer

Factor 9

Answer

Factor 8

Answer

Factor 7

Answer

Factor 11

Question 6

Marginal zone lymphoma is a type of:

Accepted Answer

B cell lymphoma

Answer

T cell lymphoma

Answer

NK cell lymphoma

Answer

Hodgkin lymphoma

Question 7

What is the chromosomal abnormality seen in promyelocytic leukemia?

Accepted Answer

t(15;17)

Answer

t(9;21)

Answer

t(9;22)

Answer

None of the above

Question 8

All are features of typical B cell Chronic Lymphocytic Leukemia (CLL), EXCEPT:

Accepted Answer

Abnormalities involving chromosome 11

Answer

Increased monoclonal B cells expressing the CD5 antigen

Answer

The peripheral blood smear shows smudge cells

Answer

Trisomy 12 is found in 25-30% of cases

Question 9

Following blood transfusion, non-cardiogenic pulmonary edema may sometimes occur because of?

Accepted Answer

Antigen-antibody mechanism involving human leukocyte antigen

Answer

RBC incompatibility

Answer

Platelet surface antigen reaction

Answer

Antibody to IgA in donor plasma

Question 10

Which of the following is NOT included in chronic myeloproliferative disorders?

Accepted Answer

Erythroleukemia

Answer

Polycythemia vera

Answer

Chronic myeloid leukemia (CML)

Answer

Essential thrombocytosis

Hematopathology — MCQs

Hematopathology — MCQs

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