Hematopathology Practice Questions

Q: What is the CD marker for histiocytosis?

CD 1a. **Langerhans Cell Histiocytosis (LCH)** is a proliferative disorder of Langerhans cells, which are specialized dendritic cells [1]. In pathology, identifying these cells requires specific immunohistochemical (IHC) markers. **Why CD1a is the correct answer:** CD1a is the most specific and widely used diagnostic marker for Langerhans cells. It is a protein involved in presenting lipid antigens to T-cells. In the context of LCH, the presence of **CD1a** and **S100** on IHC, along with the identification of **Birbeck granules** (tennis-racket shaped organelles) on electron microscopy, confirms the diagnosis [1]. **Analysis of incorrect options:** * **CD1b, CD1c, and CD1d:** While these are also members of the CD1 family involved in lipid antigen presentation, they are not used as diagnostic markers for histiocytosis. CD1b and CD1c are expressed on various subsets of dendritic cells and B-cells, while CD1d is primarily involved in presenting lipids to NKT cells. They lack the diagnostic specificity required for LCH. **High-Yield Clinical Pearls for NEET-PG:** * **Langerin (CD207):** This is the most specific marker for LCH as it is directly associated with the formation of Birbeck granules [1]. * **BRAF V600E Mutation:** Found in approximately 50% of LCH cases; it is a common "hot topic" in molecular pathology [1]. * **Classic Triad (Hand-Schüller-Christian disease):** Calvarial bone defects, diabetes insipidus, and exophthalmos. * **Letterer-Siwe Disease:** The aggressive, multisystem form of LCH seen in infants (<2 years). **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. 629-630.

Q: Diagnostic criteria of pure red cell aplasia (PRCA) includes all of the following, except:

Thrombocytopenia. **Explanation:** **Pure Red Cell Aplasia (PRCA)** is a rare hematological syndrome characterized by a selective and severe deficiency in erythroid precursors in the bone marrow, while the production of leukocytes and platelets remains preserved [1]. **Why Thrombocytopenia is the Correct Answer:** The hallmark of PRCA is the **isolation** of the erythroid defect. By definition, granulopoiesis (white cells) and megakaryopoiesis (platelets) are normal. Therefore, **thrombocytopenia** (low platelet count) is not a feature of PRCA. If a patient presents with anemia along with thrombocytopenia or leukopenia, the diagnosis shifts toward Aplastic Anemia or Myelodysplastic Syndrome (MDS). **Analysis of Incorrect Options:** * **Severe Anemia:** This is the primary clinical manifestation. Patients typically present with symptomatic normocytic, normochromic anemia due to the cessation of red cell production. * **Reticulocyte count < 1%:** Since there is a maturation arrest or absence of erythroid precursors in the marrow, the output of new red cells into the blood is near zero, leading to profound reticulocytopenia (typically <0.5% or <10,000/µL). * **Normocellular Marrow:** Unlike Aplastic Anemia (where the marrow is hypocellular and fatty), the marrow in PRCA is generally normocellular. The diagnostic finding is the near-complete absence of erythroid precursors (<0.5% to 1%) amidst normal myeloid and megakaryocytic lineages. **High-Yield Clinical Pearls for NEET-PG:** * **Associations:** PRCA is strongly associated with **Thymoma** (10-15% of cases). Removal of the thymoma can lead to remission. * **Infections:** Acute self-limiting PRCA is often caused by **Parvovirus B19**, which targets the P-antigen on proerythroblasts (look for **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 595-596.

Q: Paroxysmal Nocturnal Hemoglobinuria (PNH) is screened by which of the following tests?

Acid ham test. **Explanation:** **Paroxysmal Nocturnal Hemoglobinuria (PNH)** is an acquired clonal hematopoietic stem cell disorder caused by a mutation in the **PIGA gene**, leading to a deficiency of GPI-anchored proteins (specifically **CD55 and CD59**). These proteins normally protect RBCs from complement-mediated lysis [1]. 1. **Why Option A is Correct:** The **Acid Ham Test (Acidified Serum Lysis Test)** is the classic confirmatory/screening test for PNH. It relies on the principle that PNH cells are hypersensitive to complement. When the patient's RBCs are placed in acidified serum (pH 6.4), the alternative complement pathway is activated, leading to the lysis of the defective PNH cells. 2. **Why Other Options are Incorrect:** * **Option B:** The **Sucrose Lysis Test** was historically used as a screening test because sucrose promotes the binding of complement to RBCs. However, it is less specific than the Ham test and has been largely phased out. * **Option C & D:** Serum haptoglobin (not hapten) levels are decreased in any intravascular hemolysis, and serum complement levels are typically normal in PNH; these are non-specific findings and not used for screening. **Clinical Pearls for NEET-PG:** * **Gold Standard Investigation:** **Flow Cytometry** is now the investigation of choice. It detects the absence of CD55 (DAF) and CD59 (MIRL) on RBCs and leukocytes. * **FLAER (Fluorescent Proaerolysin):** A highly sensitive flow cytometry-based test used to detect the absence of GPI anchors. * **Triad of PNH:** Hemolytic anemia, Pancytopenia, and Venous Thrombosis (often in unusual sites like the Budd-Chiari syndrome). * **Treatment:** **Eculizumab** (a monoclonal antibody against C5 complement) is the drug of choice.

Q: What is the most common cytogenetic abnormality in Multiple myeloma?

Deletion 13q. **Explanation:** Multiple Myeloma (MM) is characterized by a complex landscape of genetic alterations. Understanding the distinction between the "most common" and "prognostically significant" abnormalities is crucial for NEET-PG. **1. Why Deletion 13q is correct:** **Deletion 13q** is the most frequent cytogenetic abnormality in Multiple Myeloma, detected in approximately **50% of cases** by conventional cytogenetics and up to **80-90%** using Fluorescence In Situ Hybridization (FISH). It often involves the loss of the *RB1* (Retinoblastoma) gene and is considered an early event in the pathogenesis of the disease. **2. Analysis of Incorrect Options:** * **Trisomy 12:** This is the most common chromosomal abnormality in **Chronic Lymphocytic Leukemia (CLL)**, not Multiple Myeloma. MM is more commonly associated with odd-numbered trisomies (Hyperdiploidy), such as trisomies of chromosomes 3, 5, 7, 9, 11, and 15. * **t(11;14):** This translocation involves the *CCND1* (Cyclin D1) gene. While it is the most common **translocation** in MM (occurring in ~15% of cases), its overall frequency is lower than Deletion 13q. It is also the hallmark of Mantle Cell Lymphoma. * **t(4;14):** This involves the *FGFR3* and *MMSET* genes. It occurs in about 15% of patients and is significant because it indicates a **poor prognosis**, but it is not the most common. **Clinical Pearls for NEET-PG:** * **Most common overall abnormality:** Deletion 13q. * **Most common translocation:** t(11;14). * **Poor Prognostic Markers (High Yield):** del(17p) [loss of TP53], t(4;14), and t(14;16). * **Good Prognostic Markers:** Hyperdiploidy and t(11;14). * **CRAB Criteria:** Remember **C**alcium (high) [1], **R**enal insufficiency [1], **A**nemia [1], and **B**one lesions [1] for clinical diagnosis. **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. 608-609.

Question 1

In Promyelocytic Leukemia, which of the following is NOT a typical feature?

Accepted Answer

CD15 and CD34 markers are positive on the same cell population.

Answer

All-trans retinoic acid is a key component of treatment.

Answer

A characteristic chromosomal translocation is t(15;17).

Answer

It is commonly associated with Disseminated Intravascular Coagulation (DIC).

Question 2

What is the CD marker for histiocytosis?

Accepted Answer

CD 1a

Answer

CD 1b

Answer

CD 1c

Answer

CD 1d

Question 3

How will you differentiate a mediastinal mass being a thymoma or acute lymphoblastic leukemia?

Accepted Answer

Cytokeratin

Answer

CD1a

Answer

CD3

Answer

Tdt

Question 4

Diagnostic criteria of pure red cell aplasia (PRCA) includes all of the following, except:

Accepted Answer

Thrombocytopenia

Answer

Severe anemia

Answer

Reticulocyte count < 1%

Answer

Normocellular marrow

Question 5

Which of the following are characteristic markers for Hodgkin's Lymphoma?

Accepted Answer

CD15 and CD30

Answer

CD15 and CD45

Answer

CD30 and CD68

Answer

CD15 and CD3

Question 6

Pancytopenia with a cellular bone marrow is seen in which of the following conditions?

Accepted Answer

Paroxysmal nocturnal hemoglobinuria (PNH)

Answer

Glucose-6-phosphate dehydrogenase (G6PD) deficiency

Answer

Acquired aplastic anemia

Answer

Thalassemia

Question 7

Paroxysmal Nocturnal Hemoglobinuria (PNH) is screened by which of the following tests?

Accepted Answer

Acid ham test

Answer

Sucrose lysis test

Answer

Serum hapten levels

Answer

Low serum complement levels

Question 8

What is the most common cytogenetic abnormality in Multiple myeloma?

Accepted Answer

Deletion 13q

Answer

Trisomy 12

Answer

Translocation t(4;14)

Answer

Translocation t(11;14)

Question 9

A 59-year-old male presents with multiple neck swellings, fever, and weight loss. He has a history of hypertension. Examination reveals painless lymphadenopathy in the neck, and blood investigations show anemia. Lymph node biopsy shows characteristic 'owl eye' shaped cells. What is the most probable diagnosis for this patient?

Accepted Answer

Hodgkin’s lymphoma

Answer

Multiple myeloma

Answer

Non-Hodgkin’s lymphoma

Answer

Burkitt’s lymphoma

Question 10

Which of the following is the most likely cause of non-megaloblastic macrocytic anemia?

Accepted Answer

Hypothyroidism

Answer

Vitamin B12 deficiency

Answer

Thiamine deficiency

Answer

Folic acid deficiency

Hematopathology — MCQs

Hematopathology — MCQs

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