Hematopathology — MCQs

A 38-year-old male presents with increasing weakness and a markedly elevated peripheral leukocyte count. Laboratory testing on peripheral blood finds a decreased leukocyte alkaline phosphatase (LAP) score, and chromosomal studies on a bone marrow aspirate find the presence of a Philadelphia chromosome. This abnormality refers to a characteristic chromosomal translocation that involves which oncogene?

Q798Medium

Tear drop cells together with leukoerythroblastosis are seen in which condition?

Q799Medium

Which laboratory test differentiates leukemoid reaction from chronic myeloid leukemia?

Q800Easy

Hemophilia is due to deficiency of which coagulation factor?

Hematopathology Indian Medical PG Practice Questions and MCQs

Question 791: Reed Sternberg cells are characteristically seen in:

A. Non-specific infection
B. Burkitt's lymphoma
C. Acute myeloid leukemia
D. Hodgkin's lymphoma (Correct Answer)

Explanation: ### Explanation **Correct Option: D. Hodgkin's lymphoma** Reed-Sternberg (RS) cells are the diagnostic hallmark of **Hodgkin’s Lymphoma (HL)** [1]. These are giant cells (15–45 µm) derived from germinal center B-cells [1]. The classic RS cell is multinucleated or bilobed (mirror-image nuclei) with prominent, eosinophilic, "owl-eye" nucleoli [2]. While they are essential for diagnosis, they typically make up only 1–5% of the total tumor mass; the remainder consists of a reactive background of lymphocytes, plasma cells, and eosinophils [1]. **Why other options are incorrect:** * **A. Non-specific infection:** These typically show reactive lymphoid hyperplasia or granulomas. While "RS-like" cells can rarely appear in infectious mononucleosis (EBV), they are not a characteristic diagnostic feature. * **B. Burkitt's lymphoma:** This is a high-grade B-cell NHL characterized by a **"starry-sky" appearance** (tingible body macrophages against a sea of small malignant B-cells) and the t(8;14) translocation involving the *MYC* gene. * **C. Acute myeloid leukemia (AML):** The hallmark of AML is the presence of **Auer rods** within myeloblasts, not RS cells. **High-Yield Clinical Pearls for NEET-PG:** * **Immunophenotype:** Classic RS cells are typically **CD15+ and CD30+**, but **CD45 negative**. * **Variants:** * *L&H Cells (Popcorn cells):* Seen in Nodular Lymphocyte Predominant HL (CD20+, CD45+) [4]. * *Lacunar cells:* Seen in Nodular Sclerosis subtype [2]. * **Bimodal Age Distribution:** HL shows peaks in the 20s and again after age 50 [1]. * **EBV Association:** Most common in the Mixed Cellularity subtype [3]. **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 792: Which one of the following red cell abnormalities is most indicative of hemolysis?

A. Target cells (Correct Answer)
B. Acanthocytes
C. Schistocytes
D. Basophilic stippling

Explanation: **Explanation** The correct answer is **Target cells (Codocytes)**. In the context of hemolysis, target cells are a hallmark of **Thalassemia** (a microcytic hypochromic hemolytic anemia) [5] and **Hemoglobin C disease**. They form due to an increase in the surface area-to-volume ratio, occurring when there is either a decrease in hemoglobin content (as seen in Thalassemia) or an increase in membrane lipid (as seen in liver disease). **Analysis of Options:** * **Target Cells (A):** These are highly indicative of hemoglobinopathies like Thalassemia [4], where premature destruction of red cells (hemolysis) occurs both in the bone marrow and the spleen. * **Acanthocytes (B):** These are "spur cells" with irregular projections, most commonly associated with **Abetalipoproteinemia** or severe liver disease, rather than primary hemolytic processes. * **Schistocytes (C):** While schistocytes (fragmented cells) are classic markers of **Microangiopathic Hemolytic Anemia (MAHA)**, the question asks for the most indicative sign among the provided options in a general hematopathology context. *Note: In many clinical scenarios, Schistocytes are considered the "gold standard" for mechanical hemolysis, but Target cells are the classic association for hereditary hemolytic anemias like Thalassemia.* * **Basophilic Stippling (D):** This represents ribosomal precipitates. While seen in Thalassemia, it is most classically associated with **Lead poisoning** and sideroblastic anemia. **NEET-PG High-Yield Pearls:** * **Target Cells Mnemonic (HALT):** **H**bC disease, **A**splenia, **L**iver disease, **T**halassemia. * **Bite Cells/Degmacytes:** Pathognomonic for **G6PD Deficiency** (oxidative hemolysis) [1]. * **Spherocytes:** Indicative of **Hereditary Spherocytosis** or Autoimmune Hemolytic Anemia (AIHA) [2], [3]. * **Schistocytes:** Always look for these in cases of DIC, HUS, or TTP. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Red Blood Cell and Bleeding Disorders, pp. 642-643. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 597-598. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 602-603. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Red Blood Cell and Bleeding Disorders, p. 638. [5] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 600-601.

Question 793: In Pelger-Huët anomaly, what is the characteristic finding in neutrophils?

A. Most of the neutrophils are bilobed (Correct Answer)
B. Lymphocytic nucleus becomes indented
C. Monocytic nuclei lose their notch
D. Neutrophils become hypersegmented

Explanation: ### Explanation **Pelger-Huët Anomaly (PHA)** is an autosomal dominant inherited condition characterized by a failure of normal nuclear segmentation in granulocytes, particularly neutrophils. **1. Why Option A is Correct:** The hallmark of PHA is **hyposegmentation**. In this condition, the neutrophil nucleus fails to segment into the typical 3–5 lobes. Instead, the majority of neutrophils appear **bilobed** (often described as "pince-nez" or spectacle-like) or even round/oval (monolobed). This is caused by a mutation in the **Lamin B Receptor (LBR)** gene, which is essential for maintaining the integrity of the nuclear envelope and chromatin structure. Despite the abnormal shape, the neutrophils function normally. **2. Why the Other Options are Incorrect:** * **Option B & C:** PHA specifically affects the granulocytic lineage (neutrophils, eosinophils, basophils). It does not typically involve morphological changes in lymphocytes or monocytes. * **Option D:** Hypersegmented neutrophils (5 or more lobes) are the opposite of PHA and are characteristic of **Megaloblastic Anemia** (Vitamin B12 or Folate deficiency) [1]. **3. Clinical Pearls for NEET-PG:** * **Pseudo-Pelger-Huët Anomaly:** This is an *acquired* form seen in **Myelodysplastic Syndromes (MDS)**, Acute Myeloid Leukemia (AML), or certain drug therapies [2]. Unlike the inherited form, it usually affects only a fraction of neutrophils. * **Pince-nez appearance:** This is a classic buzzword for the bilobed nuclei connected by a thin filament of chromatin. * **Functionality:** Inherited PHA is a benign condition; the cells have normal chemotaxis and phagocytic activity. Its primary clinical significance is avoiding a misdiagnosis of a "left shift" (increased bands) or infection. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Red Blood Cell and Bleeding Disorders, p. 654. [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. 622-624.

Question 794: Which of the following is NOT a characteristic feature of non-Hodgkin lymphoma?

A. Arises in a single node or chain of nodes (Correct Answer)
B. Non-contiguous spread in an unpredictable fashion
C. Mesenteric nodes and Waldeyer's ring are involved
D. Extranodal involvement

Explanation: To differentiate between Hodgkin Lymphoma (HL) and Non-Hodgkin Lymphoma (NHL), it is essential to understand their patterns of spread and clinical presentation. ### **Explanation of the Correct Option** **Option A (Arises in a single node or chain of nodes)** is a characteristic feature of **Hodgkin Lymphoma**, not NHL [1]. HL typically originates in a single lymph node group (most commonly cervical) and spreads in an orderly, contiguous fashion to the next anatomical chain [2]. In contrast, NHL is characterized by multicentric involvement, often appearing in multiple peripheral nodes simultaneously at the time of diagnosis [1]. ### **Analysis of Incorrect Options** * **Option B (Non-contiguous spread):** Unlike HL, NHL does not follow an anatomical sequence [1]. It spreads unpredictably via the bloodstream, often skipping adjacent node groups [2]. * **Option C (Mesenteric nodes and Waldeyer's ring):** These sites are frequently involved in NHL. Conversely, involvement of Waldeyer’s ring and mesenteric lymph nodes is extremely rare in Hodgkin Lymphoma. * **Option D (Extranodal involvement):** NHL frequently presents in extranodal sites (e.g., GI tract, skin, bone marrow, or CNS) in about 25-30% of cases [1]. HL rarely presents with primary extranodal disease. ### **High-Yield Clinical Pearls for NEET-PG** | Feature | Hodgkin Lymphoma (HL) | Non-Hodgkin Lymphoma (NHL) | | :--- | :--- | :--- | | **Spread** | Contiguous/Orderly | Non-contiguous/Hematogenous | | **Nodal Involvement** | Central (Mediastinal/Cervical) | Peripheral/Multicentric | | **Waldeyer’s Ring** | Rarely involved | Commonly involved | | **Extranodal** | Rare | Common | | **Cell Type** | Reed-Sternberg (RS) cells | B-cells (85%) or T-cells | **Mnemonic:** Remember **"H"** for Hodgkin = **H**ealthy (orderly) spread; **"N"** for NHL = **N**on-contiguous/ **N**oisy (unpredictable) spread. **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] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Diseases Of The Urinary And Male Genital Tracts, pp. 557-558.

Question 795: An anemic patient has the following red cell indexes: mean corpuscular volume, 70 mm 3 ; mean corpuscular hemoglobin, 22 pg; and mean corpuscular hemoglobin concentration, 34%. These values are most consistent with which diagnosis?

A. Folic acid-deficiency anemia
B. Iron-deficiency anemia
C. Pernicious anemia
D. Thalassemia minor (Correct Answer)

Explanation: ### Explanation The patient presents with **microcytic** (MCV 70 fL; normal 80–100) and **hypochromic** (MCH 22 pg; normal 27–32) indices [1]. However, the **MCHC is 34%**, which is within the **normal range** (32–36%). This specific combination is a classic hallmark of **Thalassemia minor** [2]. In Thalassemia minor, there is a quantitative defect in globin chain synthesis [3], but the hemoglobin that *is* produced is concentrated normally within the smaller cells [2]. This results in a "disproportionate" microcytosis (very low MCV) relative to the mild degree of anemia, often with a normal or near-normal MCHC. **Analysis of Incorrect Options:** * **Iron-deficiency anemia (B):** While microcytic and hypochromic, IDA typically shows a **low MCHC** (<30%) because hemoglobin synthesis is severely limited by iron availability, leading to "pale" cells [1]. * **Folic acid-deficiency (A) & Pernicious anemia (C):** These are **megaloblastic anemias** characterized by **macrocytosis** (MCV >100 fL) due to impaired DNA synthesis. They are physiologically opposite to the findings in this case. **NEET-PG High-Yield Pearls:** 1. **Mentzer Index:** (MCV/RBC count). A ratio **<13** suggests Thalassemia; **>13** suggests Iron Deficiency Anemia. Thalassemia typically presents with a high RBC count despite low Hb. 2. **RDW (Red Cell Distribution Width):** Usually **normal** in Thalassemia minor (homogenous cell population) but **elevated** in Iron Deficiency Anemia (anisocytosis) [1]. 3. **MCHC:** It is the most stable index. A low MCHC is the definition of hypochromia, but in Thalassemia trait, the microcytosis is often more pronounced than the hypochromia. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 590-591. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Red Blood Cell and Bleeding Disorders, pp. 649-650. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Red Blood Cell and Bleeding Disorders, p. 638.

Question 796: Which blood product has the maximum shelf life?

A. Whole blood
B. Fresh Frozen Plasma (FFP) (Correct Answer)
C. Packed Red Blood Cells (PRBC)
D. Platelet concentrate

Explanation: The shelf life of blood products is determined by the metabolic requirements of the cells, the preservative used, and the storage temperature. ### **Explanation of the Correct Answer** **Fresh Frozen Plasma (FFP)** has the maximum shelf life because it is stored in a frozen state at temperatures of **-18°C or colder**. At these temperatures, the degradation of coagulation factors is significantly slowed, allowing FFP to be stored for up to **1 year**. If stored at -65°C, the shelf life can extend up to 7 years. ### **Analysis of Incorrect Options** * **Whole Blood:** Typically stored at 2-6°C. Its shelf life depends on the anticoagulant-preservative solution used: **35 days** with CPDA-1 and 21 days with CPD/ACD. * **Packed Red Blood Cells (PRBC):** Similar to whole blood, PRBCs are stored at 2-6°C. With additive solutions like SAGM (Saline-Adenine-Glucose-Mannitol), the shelf life is extended to **42 days**. * **Platelet Concentrate:** Platelets have the shortest shelf life (**5 days**) because they must be stored at room temperature (20-24°C) with continuous agitation to maintain viability and prevent aggregation. Storage is limited due to the high risk of bacterial growth at these temperatures. ### **High-Yield Facts for NEET-PG** * **Cryoprecipitate:** Like FFP, it is stored at -18°C and has a shelf life of **1 year**. * **Irradiated RBCs:** Shelf life is reduced to **28 days** from the date of irradiation. * **Frozen RBCs:** Can be stored for up to **10 years** in glycerol at -65°C (rarely used, but technically the longest). * **Thawed FFP:** Once thawed, it must be used within **24 hours** if stored at 1-6°C.

Question 797: A 38-year-old male presents with increasing weakness and a markedly elevated peripheral leukocyte count. Laboratory testing on peripheral blood finds a decreased leukocyte alkaline phosphatase (LAP) score, and chromosomal studies on a bone marrow aspirate find the presence of a Philadelphia chromosome. This abnormality refers to a characteristic chromosomal translocation that involves which oncogene?

A. bcl-2 erb-B
B. c-abl (Correct Answer)
C. c-myc
D. erb-B

Explanation: ### Explanation The clinical presentation of a middle-aged male with a markedly elevated leukocyte count, a low **Leukocyte Alkaline Phosphatase (LAP) score**, and the presence of the **Philadelphia chromosome (Ph+)** is diagnostic of **Chronic Myeloid Leukemia (CML)** [1]. **1. Why the correct answer is right:** The Philadelphia chromosome results from a reciprocal translocation between chromosomes 9 and 22, denoted as **t(9;22)(q34;q11)** [3]. This translocation involves the movement of the **c-abl** proto-oncogene from chromosome 9 to the **bcr** (breakpoint cluster region) on chromosome 22 [1]. The resulting **BCR-ABL1 fusion gene** encodes a chimeric protein with constitutive **tyrosine kinase activity**, which drives uncontrolled myeloid proliferation [2]. **2. Why the incorrect options are wrong:** * **A & D (erb-B):** The *erb-B* family (e.g., HER2/neu) encodes epidermal growth factor receptors. Overexpression is typically associated with solid tumors like breast and gastric carcinomas, not CML. * **A (bcl-2):** The *bcl-2* gene is an anti-apoptotic marker involved in the **t(14;18)** translocation, which is the hallmark of **Follicular Lymphoma**. * **C (c-myc):** The *c-myc* oncogene is a transcription factor involved in the **t(8;14)** translocation, which is characteristic of **Burkitt Lymphoma**. **3. High-Yield Clinical Pearls for NEET-PG:** * **LAP Score:** Decreased in CML and Paroxysmal Nocturnal Hemoglobinuria (PNH); increased in Leukemoid reactions and Polycythemia Vera. * **Treatment:** Imatinib (a tyrosine kinase inhibitor) is the first-line targeted therapy for CML. * **Blast Crisis:** CML can progress to acute leukemia (80% AML, 20% ALL). * **Cytogenetics:** The Philadelphia chromosome is found in >95% of CML cases and is also a poor prognostic marker in Adult B-ALL [2]. **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] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 605-607.

Question 798: Tear drop cells together with leukoerythroblastosis are seen in which condition?

A. Megaloblastic anemia
B. Iron deficiency anemia
C. Aplastic anemia
D. Primary myelofibrosis (Correct Answer)

Explanation: **Explanation:** The presence of **Tear drop cells (Dacrocytes)** alongside a **leukoerythroblastic blood picture** is the classic hematological hallmark of **Primary Myelofibrosis (PMF)** [1]. **1. Why Primary Myelofibrosis is correct:** In PMF, reactive fibrosis of the bone marrow (mediated by TGF-̢ from megakaryocytes) replaces normal hematopoietic space [2]. * **Tear drop cells:** As RBCs are forced to squeeze through the narrow, fibrotic slits of the marrow or the distorted vasculature of an enlarged spleen, they undergo irreversible stretching, resulting in a "tear drop" shape [1]. * **Leukoerythroblastosis:** This refers to the presence of immature white cells (myelocytes, metamyelocytes) and nucleated red cells (normoblasts) in the peripheral smear [1]. This occurs because the fibrotic marrow can no longer retain cells until they mature, and extramedullary hematopoiesis (primarily in the spleen) lacks the "blood-marrow barrier" to prevent the release of immature forms [1]. **2. Why the other options are incorrect:** * **Megaloblastic Anemia:** Characterized by macro-ovalocytes and hypersegmented neutrophils. While some poikilocytosis occurs, it lacks the leukoerythroblastic picture. * **Iron Deficiency Anemia:** Characterized by microcytic hypochromic RBCs, pencil cells, and target cells. * **Aplastic Anemia:** Characterized by pancytopenia with a "dry tap" on aspiration, but the peripheral smear shows normocytic normochromic cells with a lack of immature forms (no leukoerythroblastosis). **High-Yield Clinical Pearls for NEET-PG:** * **Dry Tap:** PMF is a common cause of a "dry tap" on bone marrow aspiration; diagnosis requires a **trephine biopsy** showing increased reticulin or collagen [2]. * **Splenomegaly:** PMF typically presents with **massive splenomegaly** due to extramedullary hematopoiesis [1]. * **Mutation:** Approximately 50-60% of cases are associated with the **JAK2 V617F mutation** [2]. * **Dacrocyte Mnemonic:** "The marrow weeps (tear drops) because it is scarred (fibrosis)." **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. 628-629. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 614-616.

Question 799: Which laboratory test differentiates leukemoid reaction from chronic myeloid leukemia?

A. Leukocyte alkaline phosphatase (LAP) (Correct Answer)
B. Leukocyte common antigen (LCA)
C. Myelo-peroxidase (MPO)
D. Tartrate resistant alkaline phosphatase (TRAP)

Explanation: ### Explanation The differentiation between a **Leukemoid Reaction** (a reactive increase in WBCs due to infection/stress) and **Chronic Myeloid Leukemia (CML)** is a classic high-yield topic in hematopathology. **1. Why LAP is the Correct Answer:** The **Leukocyte Alkaline Phosphatase (LAP) score** (also known as the Neutrophil Alkaline Phosphatase/NAP score) measures the enzyme activity within the secondary granules of mature neutrophils. * **Leukemoid Reaction:** Neutrophils are functionally normal and "activated" by inflammation, leading to a **High LAP score**. * **CML:** The malignant neutrophils are biochemically defective and lack this enzyme, resulting in a **Low LAP score**. **2. Analysis of Incorrect Options:** * **Leukocyte Common Antigen (LCA/CD45):** This is a pan-leukocyte marker used in immunohistochemistry to differentiate lymphomas/leukemias from non-hematopoietic tumors (like carcinomas). It does not differentiate between types of myeloid proliferation. * **Myelo-peroxidase (MPO):** This enzyme is present in most myeloid cells. While it helps distinguish Acute Myeloid Leukemia (AML) from Acute Lymphoblastic Leukemia (ALL), it remains positive in both CML and leukemoid reactions. * **Tartrate-Resistant Acid Phosphatase (TRAP):** This is the specific diagnostic marker for **Hairy Cell Leukemia**. **3. Clinical Pearls for NEET-PG:** * **The Gold Standard:** While LAP was historically the primary test, the definitive way to diagnose CML today is identifying the **Philadelphia Chromosome t(9;22)** or the **BCR-ABL1** fusion gene via FISH or PCR [1]. * **Basophilia:** The presence of increased basophils strongly favors CML over a leukemoid reaction [3]. * **Splenomegaly:** Massive splenomegaly is a hallmark of CML but is typically absent in a leukemoid reaction [2]. * **LAP Score Variations:** * **Low:** CML, Paroxysmal Nocturnal Hemoglobinuria (PNH), Hypophosphatasia. * **High:** Leukemoid reaction, Polycythemia Vera, Pregnancy, and Stress/Infection. **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. 624-625. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 611-612. [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, p. 592.

Question 800: Hemophilia is due to deficiency of which coagulation factor?

A. Factor I
B. Factor V
C. Factor VIII (Correct Answer)
D. Factor XIII

Explanation: ### Explanation **Correct Answer: C. Factor VIII** **Understanding the Concept:** Hemophilia is a group of hereditary bleeding disorders caused by deficiencies in specific clotting factors within the intrinsic pathway of the coagulation cascade. * **Hemophilia A (Classic Hemophilia):** This is the most common type (approx. 80% of cases) and is caused by a deficiency or dysfunction of **Factor VIII** [1]. * **Hemophilia B (Christmas Disease):** Caused by a deficiency of **Factor IX**. Both are inherited in an **X-linked recessive** pattern, primarily affecting males [1]. Because Factor VIII acts as a cofactor for Factor IXa to activate Factor X, its deficiency leads to impaired fibrin clot formation, resulting in prolonged bleeding [1]. **Analysis of Incorrect Options:** * **Option A (Factor I):** Deficiency of Factor I (Fibrinogen) leads to Afibrinogenemia or Hypofibrinogenemia, which are rare autosomal recessive disorders. * **Option B (Factor V):** Deficiency causes Owren’s disease (Parahemophilia), a rare autosomal recessive bleeding disorder. Factor V is a cofactor in the common pathway. * **Option D (Factor XIII):** Deficiency of the Fibrin Stabilizing Factor leads to poor wound healing and delayed bleeding, as the initial clot is formed but cannot be cross-linked. **NEET-PG High-Yield Pearls:** 1. **Laboratory Findings:** Characterized by **Prolonged aPTT** with a **Normal PT** and **Normal Bleeding Time** (platelet function is unaffected). 2. **Clinical Presentation:** Hallmark is **Hemarthrosis** (bleeding into joints, most commonly the knee) and deep muscle hematomas. 3. **Mixing Studies:** In Hemophilia, the prolonged aPTT **corrects** when mixed with normal plasma (distinguishes it from Factor VIII inhibitors). 4. **Treatment:** Recombinant Factor VIII concentrate is the mainstay. Desmopressin (DDAVP) can be used in mild Hemophilia A to release stored Factor VIII from Weibel-Palade bodies. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Red Blood Cell and Bleeding Disorders, pp. 670-671.

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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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