Hematopathology — MCQs

A 72-year-old man who has undergone aortic valve replacement presents with pallor and fatigue. Laboratory findings include a decreased red blood cell count, the presence of schistocytes on peripheral blood smear examination, and significantly elevated indirect (unconjugated) bilirubin. What is the likely cause of this patient's anemia?

Q617Easy

t(2,8) is characteristically seen with which of the following conditions?

Q618Easy

Which of the following conditions is associated with the MYD88 L265P mutation?

Q619Medium

All of the following are true for the Philadelphia chromosome, EXCEPT:

Q620Easy

Which of the following is NOT a preliminary investigation for primary coagulation defects?

Hematopathology Indian Medical PG Practice Questions and MCQs

Question 611: Which of the following is the only hemolytic anemia caused by an acquired intrinsic defect in the cell membrane?

A. Sickle cell anemia
B. Thalassemia
C. Paroxysmal nocturnal hemoglobinuria (PNH) (Correct Answer)
D. None of the above

Explanation: ### Explanation **Correct Answer: C. Paroxysmal nocturnal hemoglobinuria (PNH)** **Why it is correct:** Hemolytic anemias are broadly classified into **extrinsic** (extra-corpuscular) and **intrinsic** (intra-corpuscular) defects. Intrinsic defects are almost always hereditary (e.g., Spherocytosis, G6PD deficiency). **PNH is the unique exception**—it is the only hemolytic anemia caused by an **acquired intrinsic defect** [1], [2]. The underlying pathology involves a somatic mutation in the **PIGA gene** within hematopoietic stem cells [2]. This mutation leads to a deficiency of **GPI-anchored proteins** on the cell membrane, specifically **CD55 (DAF)** and **CD59 (MIRL)** [1]. These proteins normally protect the cell from complement-mediated lysis. Their absence makes the RBCs (and other lineages) hypersensitive to complement destruction, leading to intravascular hemolysis [1]. **Why the other options are incorrect:** * **A. Sickle cell anemia:** This is a **hereditary** (congenital) intrinsic defect caused by a point mutation in the β-globin gene, leading to abnormal hemoglobin (HbS) [3]. * **B. Thalassemia:** This is a **hereditary** (congenital) intrinsic defect characterized by decreased synthesis of alpha or beta-globin chains [3]. **High-Yield Clinical Pearls for NEET-PG:** * **Triad of PNH:** Hemolytic anemia, Pancytopenia, and Venous thrombosis (often in unusual sites like the Budd-Chiari syndrome) [1]. * **Gold Standard Diagnosis:** **Flow Cytometry** (shows absence of CD55 and CD59) [1]. * **Ham’s Test & Sucrose Lysis Test:** Historical tests; now replaced by flow cytometry. * **Treatment:** **Eculizumab** (a monoclonal antibody against Complement C5). * **Complications:** PNH can evolve into Aplastic Anemia or Acute Myeloid Leukemia (AML). **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Red Blood Cell and Bleeding Disorders, pp. 650-651. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 601-602. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Red Blood Cell and Bleeding Disorders, pp. 652-654.

Question 612: Translocation of t(8;14) is characteristic of which of the following malignancies?

A. Burkitt's lymphoma (Correct Answer)
B. Hairy cell leukemia
C. Mantle cell lymphoma
D. Follicular lymphoma

Explanation: **Explanation:** The translocation **t(8;14)** is the hallmark genetic abnormality of **Burkitt’s lymphoma** [1]. This translocation involves the juxtaposition of the **c-MYC proto-oncogene** on chromosome 8 with the **Immunoglobulin Heavy chain (IgH)** gene promoter on chromosome 14 [1]. This results in the constitutive overexpression of the c-MYC transcription factor, leading to rapid cellular proliferation and the classic "starry-sky" appearance on histology [2]. **Analysis of Incorrect Options:** * **Hairy cell leukemia:** This is not associated with a specific reciprocal translocation but is characterized by the **BRAF V600E mutation**. It typically presents with massive splenomegaly and "dry tap" on bone marrow aspiration. * **Mantle cell lymphoma:** Characterized by **t(11;14)**, which leads to the overexpression of **Cyclin D1** (PRAD-1 gene), promoting cell cycle progression from G1 to S phase. * **Follicular lymphoma:** Characterized by **t(14;18)**, which results in the overexpression of the **BCL-2** anti-apoptotic protein, preventing programmed cell death in B-cells [3]. **High-Yield Clinical Pearls for NEET-PG:** * **Burkitt’s Lymphoma Variants:** Endemic (African, associated with EBV, involves the jaw), Sporadic (abdominal involvement), and Immunodeficiency-associated. * **Morphology:** Medium-sized B-cells with multiple nucleoli and a high mitotic index [2]. * **Immunophenotype:** CD19+, CD20+, CD10+, and **BCL-6+**; notably **BCL-2 negative**. * **Ki-67 index:** Typically approaches **100%**, reflecting the extreme proliferation rate. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 324-325. [2] 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, p. 606. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Diseases Of The Urinary And Male Genital Tracts, pp. 561-562.

Question 613: Massive splenomegaly is seen in all of the following conditions, except?

A. Hairy cell leukemia
B. Myelofibrosis
C. Chronic myeloid leukemia (CML)
D. Hepatic vein obstruction (Correct Answer)

Explanation: ### Explanation Splenomegaly is categorized based on the weight or palpable distance of the spleen. **Massive splenomegaly** is defined as a spleen weighing >1000g or extending >8 cm below the left costal margin [3]. **Why Hepatic Vein Obstruction is the Correct Answer:** Hepatic vein obstruction (Budd-Chiari Syndrome) leads to **congestive splenomegaly**. In portal hypertension or venous outflow obstruction, the spleen undergoes chronic passive congestion. While the spleen does enlarge, it typically results in **moderate splenomegaly** (500–1000g). It rarely, if ever, reaches the "massive" proportions seen in myeloproliferative or storage disorders [5]. **Analysis of Incorrect Options:** * **Myelofibrosis & Chronic Myeloid Leukemia (CML):** These are Myeloproliferative Neoplasms (MPN). In these conditions, the spleen becomes a site of massive **extramedullary hematopoiesis** or leukemic infiltration, often filling the entire left abdomen and crossing the midline [1], [4]. * **Hairy Cell Leukemia:** This is a classic cause of massive splenomegaly. The splenic red pulp is densely infiltrated by "hairy" B-cells, leading to significant organomegaly, often in the absence of lymphadenopathy. **High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic for Massive Splenomegaly (M3 CH):** **M**yelofibrosis, **M**alaria (Tropical Splenomegaly Syndrome), **M**yeloid Leukemia (CML), **C**ala-azar (Visceral Leishmaniasis), **H**airy Cell Leukemia, and **G**aucher Disease [2]. * **Mild Splenomegaly (<500g):** Acute splenitis, Infectious mononucleosis, SLE. * **Gaucher Disease:** The most common lysosomal storage disorder causing massive splenomegaly. * **Splenic Infarction:** Most commonly occurs in massive splenomegaly (especially CML) due to the outstripping of blood supply [1]. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 611-612. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Diseases Of The Urinary And Male Genital Tracts, pp. 568-569. [3] 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. 631-632. [4] 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. 628-629. [5] 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. 632-634.

Question 614: What is the marker for granulocytic sarcoma?

A. CD33
B. CD38
C. CD117 (Correct Answer)
D. CD137

Explanation: **Explanation:** **Granulocytic Sarcoma** (also known as Myeloid Sarcoma or Chloroma) is an extramedullary tumor mass composed of myeloid blasts, occurring either de novo or as a manifestation of Acute Myeloid Leukemia (AML), Myeloproliferative Neoplasms (MPN), or Myelodysplastic Syndromes (MDS). **Why CD117 is the correct answer:** CD117 (c-kit) is a proto-oncogene that encodes a receptor tyrosine kinase [1]. It is a highly sensitive and specific marker for hematopoietic progenitor cells of the myeloid lineage. In the context of granulocytic sarcoma, **CD117** is considered the most reliable immunohistochemical marker for identifying immature myeloid cells (blasts), often showing positivity in 80-90% of cases. Other important markers include Myeloperoxidase (MPO) and CD43. **Analysis of Incorrect Options:** * **CD33:** While CD33 is a pan-myeloid marker expressed on mature and immature myeloid cells, it is often less reliable in paraffin-embedded tissue sections compared to CD117 for diagnosing myeloid sarcoma. * **CD38:** This is a marker for activated T-cells, B-cells, and plasma cells. It is the classic marker used for identifying **Multiple Myeloma** and plasma cell dyscrasias. * **CD137:** Also known as 4-1BB, this is a costimulatory molecule found on activated T-cells and NK cells; it has no diagnostic role in myeloid tumors. **High-Yield Clinical Pearls for NEET-PG:** * **Common Sites:** Bone, periosteum, soft tissue, and lymph nodes. * **The "Chloroma" effect:** The tumor may appear green upon gross inspection due to the presence of the **Myeloperoxidase (MPO)** enzyme. * **Differential Diagnosis:** It is frequently misdiagnosed as Non-Hodgkin Lymphoma (NHL); therefore, IHC markers like CD117 and MPO are crucial for differentiation. * **Association:** Most commonly associated with AML with **t(8;21)** [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, p. 620.

Question 615: RS cells are characteristic of which of the following conditions?

A. Hodgkin's disease (Correct Answer)
B. Sickle cell anemia
C. Thalassemia
D. Chronic myeloid leukemia

Explanation: **Explanation:** **Reed-Sternberg (RS) cells** are the hallmark diagnostic feature of **Hodgkin’s Lymphoma (HL)** [1]. These are large, multinucleated or polylobated B-cells, typically characterized by an "owl-eye" appearance due to prominent, eosinophilic, inclusion-like nucleoli [2]. While they are essential for diagnosis, they usually constitute only 1–5% of the total tumor mass, which is predominantly composed of a reactive background of lymphocytes, plasma cells, and eosinophils [1]. **Analysis of Options:** * **Hodgkin’s Disease (Correct):** RS cells are derived from germinal center B-cells [1]. The classic phenotype is **CD15+ and CD30+**, but notably **CD45 negative**. * **Sickle Cell Anemia:** This is a hemoglobinopathy characterized by **Sickle cells (drepanocytes)** and Howell-Jolly bodies (post-autosplenectomy) on peripheral smear, not RS cells. * **Thalassemia:** A quantitative defect in globin chain synthesis. Peripheral smear typically shows **Target cells (codocytes)**, microcytic hypochromic RBCs, and basophilic stippling. * **Chronic Myeloid Leukemia (CML):** A myeloproliferative neoplasm characterized by the **Philadelphia chromosome t(9;22)** and the presence of the *BCR-ABL1* fusion gene. The smear shows a full spectrum of myeloid cells (myelocytes, metamyelocytes) and basophilia. **High-Yield Clinical Pearls for NEET-PG:** * **Variants of RS cells:** * *Lacunar cells:* Seen in Nodular Sclerosis HL [2]. * *Popcorn cells (L&H cells):* Seen in Nodular Lymphocyte Predominant HL (CD20+, CD45+, but CD15- and CD30-) [4]. * *Mummified cells:* Degenerated RS cells with pyknotic nuclei. * **EBV Association:** Frequently associated with the Mixed Cellularity subtype [3]. * **Bimodal Age Distribution:** HL typically shows peaks in the 20s and after age 50 [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. 614-616. [2] 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, p. 616. [3] 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. 616-618. [4] 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, p. 618.

Question 616: A 72-year-old man who has undergone aortic valve replacement presents with pallor and fatigue. Laboratory findings include a decreased red blood cell count, the presence of schistocytes on peripheral blood smear examination, and significantly elevated indirect (unconjugated) bilirubin. What is the likely cause of this patient's anemia?

A. Cold agglutinin disease
B. Dietary deficiency
C. Hereditary spherocytosis
D. Mechanical disruption of red cells (Correct Answer)

Explanation: ### Explanation The correct answer is **D. Mechanical disruption of red cells.** **Mechanism:** This patient is presenting with **Microangiopathic Hemolytic Anemia (MAHA)**, specifically **Cardiac Valve Anemia**. In patients with prosthetic heart valves (especially mechanical ones), the high-shear stress and turbulent blood flow can cause physical trauma to red blood cells (RBCs). This mechanical disruption shears the RBCs, leading to the formation of fragmented cells known as **schistocytes** (helmet cells). Because the RBCs are destroyed within the circulation (intravascular hemolysis), there is a release of hemoglobin, which is metabolized into **unconjugated (indirect) bilirubin**, leading to jaundice and elevated lab markers [1], [2]. **Analysis of Incorrect Options:** * **A. Cold agglutinin disease:** This is an autoimmune hemolytic anemia mediated by IgM antibodies. While it causes hemolysis, the peripheral smear typically shows **RBC agglutination** (clumping) rather than schistocytes [3]. * **B. Dietary deficiency:** Iron, B12, or folate deficiencies cause anemia through impaired production. They do not typically present with schistocytes or significant elevations in indirect bilirubin (which indicates active hemolysis). * **C. Hereditary spherocytosis:** This is a membrane defect (e.g., ankyrin or spectrin deficiency) leading to extravascular hemolysis in the spleen [5]. The characteristic finding on a smear is **spherocytes** (small, dark RBCs lacking central pallor), not schistocytes [4]. **High-Yield Clinical Pearls for NEET-PG:** * **Schistocytes** are the hallmark of MAHA. Other causes include TTP, HUS, DIC, and malignant hypertension. * **Lab markers of intravascular hemolysis:** Increased LDH, increased indirect bilirubin, and **decreased haptoglobin** (due to binding of free hemoglobin) [1]. * **Iron deficiency** can sometimes occur in chronic mechanical hemolysis because the free hemoglobin is filtered by the kidneys, leading to **hemosiderinuria** [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Red Blood Cell and Bleeding Disorders, pp. 639-640. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Red Blood Cell and Bleeding Disorders, p. 640. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Red Blood Cell and Bleeding Disorders, pp. 651-652. [4] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 602-603. [5] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Red Blood Cell and Bleeding Disorders, p. 638.

Question 617: t(2,8) is characteristically seen with which of the following conditions?

A. Pre-B cell lymphoma
B. Pre-T cell lymphoma
C. Burkitt's lymphoma (Correct Answer)
D. Mantle cell lymphoma

Explanation: **Explanation:** **Burkitt’s Lymphoma** is a highly aggressive B-cell non-Hodgkin lymphoma characterized by the overexpression of the **c-MYC proto-oncogene** located on chromosome 8 [1]. The hallmark genetic feature is a reciprocal translocation involving chromosome 8 and one of the immunoglobulin (Ig) gene loci. The most common translocation is **t(8;14)** (80% of cases), involving the Ig heavy chain gene [1]. However, variant translocations occur in the remaining 20%: * **t(2;8):** Involves the **kappa (κ) light chain** gene on chromosome 2. * **t(8;22):** Involves the **lambda (λ) light chain** gene on chromosome 22. In all three translocations, c-MYC is moved adjacent to a highly active Ig promoter, leading to constitutive expression of MYC and rapid cellular proliferation [1]. **Analysis of Incorrect Options:** * **Pre-B and Pre-T cell lymphoma (Acute Lymphoblastic Leukemia/Lymphoma):** These are associated with different mutations [2]. Common translocations include t(12;21) in B-ALL (good prognosis) or t(9;22) (Philadelphia chromosome). * **Mantle cell lymphoma:** Characteristically associated with **t(11;14)**, which leads to the overexpression of **Cyclin D1** (PRAD-1 gene), promoting cell cycle progression from G1 to S phase. **High-Yield Clinical Pearls for NEET-PG:** * **Morphology:** "Starry sky" appearance (tingible body macrophages against a background of small malignant B-cells) [2]. * **Immunophenotype:** CD19+, CD20+, CD10+, and BCL-6+. Notably **BCL-2 negative**. * **Ki-67 index:** Typically nearly 100% (indicates extremely high proliferation). * **EBV Association:** Strongly linked with the Endemic (African) variant, typically presenting as a jaw mass [3]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 324-325. [2] 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, p. 606. [3] 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. 605-606.

Question 618: Which of the following conditions is associated with the MYD88 L265P mutation?

A. Waldenstrom macroglobulinemia (Correct Answer)
B. Multiple myeloma
C. Burkitt's lymphoma
D. B cell disorders

Explanation: **Explanation:** The **MYD88 L265P** mutation is a highly specific molecular marker for **Waldenstrom Macroglobulinemia (WM)**. 1. **Why Waldenstrom Macroglobulinemia is correct:** WM is a lymphoplasmacytic lymphoma (LPL) characterized by bone marrow infiltration and the production of a monoclonal IgM protein [1]. The **MYD88 L265P** mutation is present in over **90-95% of cases**. This gain-of-function mutation leads to the constitutive activation of the NF-κB signaling pathway, which promotes the survival and proliferation of malignant B cells. Detecting this mutation is crucial for differentiating WM from other small B-cell lymphomas. 2. **Why other options are incorrect:** * **Multiple Myeloma:** This is characterized by plasma cell dyscrasia and usually involves translocations of the IgH locus (e.g., t(11;14), t(4;14)) or deletions like del(17p). It does not typically harbor the MYD88 mutation. High levels of M protein in Multiple Myeloma can cause rouleaux formation [2]. The most common monoclonal Ig in myeloma is IgG [3]. * **Burkitt’s Lymphoma:** This is classically associated with the **c-MYC** gene translocation, most commonly **t(8;14)**. * **B cell disorders:** While this is a broad category, the MYD88 mutation is not a universal feature of all B-cell disorders. It is found in specific subsets (like ABC-type DLBCL), but its strongest and most diagnostic association is with WM. **High-Yield Clinical Pearls for NEET-PG:** * **Hyperviscosity Syndrome:** A classic presentation of WM due to large IgM pentamers (look for "sausage-link" retinopathy). * **Differentiating Feature:** Unlike Multiple Myeloma, WM typically presents with **hepatosplenomegaly/lymphadenopathy** and lacks lytic bone lesions or hypercalcemia (CRAB features) [1]. * **CXCR4 Mutation:** Found in about 30-40% of WM cases; it is the second most common mutation and influences resistance to certain therapies like Ibrutinib. **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. 609-610. [2] 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. 607-608. [3] 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 619: All of the following are true for the Philadelphia chromosome, EXCEPT:

A. It is an acquired genetic defect.
B. It is seen in plasma cell tumors. (Correct Answer)
C. It is a marker of chronic myeloid leukemia (CML).
D. It results from a translocation of genetic material from chromosome 22 to chromosome 9.

Explanation: The Philadelphia chromosome (Ph) is a hallmark of specific leukemias and is not associated with plasma cell dyscrasias [1], [4]. ### **Explanation of the Correct Answer (Option B)** The Philadelphia chromosome is **not** seen in plasma cell tumors (e.g., Multiple Myeloma). Plasma cell tumors are typically characterized by translocations involving the **Immunoglobulin Heavy Chain (IgH)** locus on chromosome 14, such as t(11;14) or t(4;14) [3]. ### **Analysis of Incorrect Options** * **Option A (Acquired defect):** This is true. The Ph chromosome is a somatic mutation occurring in hematopoietic stem cells; it is not an inherited (germline) condition [1]. * **Option C (Marker of CML):** This is true. It is the diagnostic hallmark of Chronic Myeloid Leukemia, present in >95% of cases [2]. Its absence in a suspected CML case suggests a different myeloproliferative neoplasm. * **Option D (Translocation):** This is true. It results from a reciprocal translocation **t(9;22)(q34;q11)** [1], [4]. This fuses the *ABL1* gene (ch 9) with the *BCR* gene (ch 22), creating the **BCR-ABL1** fusion gene. ### **High-Yield Clinical Pearls for NEET-PG** * **Molecular Consequence:** The *BCR-ABL1* fusion protein has constitutive **tyrosine kinase activity**, driving uncontrolled cell proliferation [2], [4]. * **Size Variants:** * **p210:** Classic CML. * **p190:** Associated with **B-ALL** (indicates a poor prognosis). * **p230:** Associated with Chronic Neutrophilic Leukemia (CNL). * **Treatment:** The discovery of the Ph chromosome led to the development of **Imatinib (Gleevec)**, a targeted tyrosine kinase inhibitor (TKI), which is the first-line treatment for CML. * **LAP Score:** In Ph+ CML, the Leukocyte Alkaline Phosphatase (LAP) score is characteristically **decreased**, helping differentiate it from a Leukemoid reaction. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 225-226. [2] 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, p. 624. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 324-325. [4] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 605-607.

Question 620: Which of the following is NOT a preliminary investigation for primary coagulation defects?

A. Bleeding time
B. Platelet count
C. Prothrombin time (Correct Answer)
D. Platelet aggregation studies

Explanation: Explanation: Coagulation defects are broadly classified into **Primary Hemostasis** (involving platelets and the vessel wall) and **Secondary Hemostasis** (involving the coagulation cascade/clotting factors) [1]. **Why Prothrombin Time (PT) is the correct answer:** Prothrombin Time (PT) measures the **extrinsic and common pathways** of the coagulation cascade. It is a screening test for **secondary hemostasis** (e.g., Factor VII, X, V, II, and Fibrinogen deficiencies) [3]. Since the question asks for investigations of *primary* coagulation defects, PT is the outlier as it evaluates clotting factors rather than platelet function. **Analysis of incorrect options:** * **Bleeding Time (BT):** This is the classic screening test for primary hemostasis [1]. It measures the time taken for a standardized skin wound to stop bleeding, reflecting platelet plug formation and vascular integrity. * **Platelet Count:** A fundamental preliminary test. Quantitative defects (Thrombocytopenia) are the most common cause of primary hemostatic failure [1], [5]. * **Platelet Aggregation Studies:** These are functional assays used to diagnose qualitative platelet defects (e.g., Glanzmann Thrombasthenia or Bernard-Soulier Syndrome) [4] when the count is normal but primary bleeding symptoms persist. **Clinical Pearls for NEET-PG:** * **Primary Hemostasis Defect:** Presents with petechiae, purpura, and mucosal bleeding (epistaxis, gum bleeding) [1], [2]. * **Secondary Hemostasis Defect:** Presents with deep-seated bleeds, such as hemarthrosis (joint bleeds) and hematomas [2]. * **Screening Duo:** For any bleeding disorder, the initial screen usually includes **CBC (Platelet count), BT, PT, and aPTT.** * **vWD Exception:** von Willebrand Disease is a primary hemostasis defect, but because vWF stabilizes Factor VIII, the **aPTT** may also be prolonged. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 619-620. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Red Blood Cell and Bleeding Disorders, pp. 664-665. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Red Blood Cell and Bleeding Disorders, pp. 666-667. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Red Blood Cell and Bleeding Disorders, pp. 668-669. [5] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 581-582.

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Anemias: Classification and Approach

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Hemolytic Anemias

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Myeloproliferative Neoplasms

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Myelodysplastic Syndromes

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Acute Leukemias

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Chronic Leukemias

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Lymphomas and Lymphoid Neoplasms

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Plasma Cell Disorders

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Bleeding Disorders

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Thrombotic Disorders

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