Hematopathology — MCQs

Hematopathology Indian Medical PG Practice Questions and MCQs

Question 191: Low haptoglobin in hemorrhage is masked by the concurrent presence of which of the following conditions?

A. Malnutrition
B. Pregnancy
C. Obstructive biliary disease
D. Liver parenchymal disease (Correct Answer)

Explanation: ### Explanation **Core Concept: Haptoglobin Dynamics** Haptoglobin is an acute-phase reactant protein synthesized primarily by the **liver**. Its physiological role is to bind free hemoglobin released during intravascular hemolysis or hemorrhage into closed spaces, forming a complex that is rapidly cleared by the reticuloendothelial system [1]. This process leads to **low serum haptoglobin levels** in hemolytic states [1]. **Why Liver Parenchymal Disease is Correct:** In liver parenchymal disease (e.g., cirrhosis or hepatitis), the synthetic capacity of the liver is compromised. Since haptoglobin is produced by hepatocytes, liver failure leads to **decreased production**. Therefore, if a patient has both hemorrhage/hemolysis (which consumes haptoglobin) and liver disease (which prevents its synthesis), the haptoglobin level will remain low. The liver disease "masks" the diagnostic utility of haptoglobin because you cannot determine if the low level is due to consumption (hemorrhage) or decreased production (liver failure). **Analysis of Incorrect Options:** * **Malnutrition:** While severe protein-energy malnutrition can decrease overall protein synthesis, it is not as specific or potent a cause for haptoglobin suppression as direct parenchymal damage. * **Pregnancy:** Pregnancy is generally associated with a physiological decrease in haptoglobin (due to hemodilution), but it does not specifically mask the consumption seen in hemorrhage in the same pathological context as liver failure. * **Obstructive Biliary Disease:** This typically leads to an increase in acute-phase reactants. Since haptoglobin is an acute-phase reactant, inflammation or biliary obstruction may actually **elevate** haptoglobin levels, potentially masking hemolysis by keeping levels falsely "normal." **NEET-PG High-Yield Pearls:** * **Haptoglobin** is the most sensitive laboratory indicator of **intravascular hemolysis** [1]. * **Acute Phase Reactant:** Haptoglobin levels **increase** in infection, inflammation, and malignancy. This can lead to a "false normal" haptoglobin level even in the presence of active hemolysis. * **Haptoglobin-Hemoglobin Complex:** This complex is too large to be filtered by the glomerulus, thereby preventing iron loss and renal damage (hemoglobinuria) [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.

Question 192: Non-specific esterase is present in which of the following?

A. Megakaryocytic leukemia
B. Lymphocytic leukemia
C. Erythroleukemia
D. Acute myeloid leukemia (AML) (Correct Answer)

Explanation: **Explanation:** Cytochemical stains are essential tools in differentiating Acute Myeloid Leukemia (AML) subtypes. **Non-specific esterase (NSE)**, such as alpha-naphthyl acetate esterase, is a marker used to identify cells of **monocytic lineage** [1]. 1. **Why AML is correct:** While the question lists "AML" generally, NSE is specifically the hallmark of **AML-M4 (Acute Myelomonocytic Leukemia)** and **AML-M5 (Acute Monocytic Leukemia)** [1]. In these subtypes, the monoblasts and monocytes show strong, diffuse positivity for NSE [2]. This stain is particularly useful because it is **inhibited by Sodium Fluoride (NaF)**, a classic diagnostic feature used to distinguish monocytic cells from other lineages. 2. **Why other options are incorrect:** * **Megakaryocytic leukemia (M7):** These cells are typically negative for NSE but may show positivity for Acid Phosphatase or specific markers like Platelet Peroxidase (PPO) and CD41/CD61. * **Lymphocytic leukemia (ALL):** Lymphoblasts are typically NSE negative. They are characterized by **PAS (Periodic Acid-Schiff)** positivity in a "block-like" pattern and are MPO negative. * **Erythroleukemia (M6):** These cells are characterized by intense **PAS positivity** in the erythroblasts; they do not typically express NSE. **High-Yield Clinical Pearls for NEET-PG:** * **Myeloperoxidase (MPO):** The most specific stain for the **myeloid** series (M1, M2, M3, M4). * **NSE:** Best for **monocytic** series (M4, M5) [1]. * **Sudan Black B (SBB):** Stains phospholipids; mirrors MPO but is slightly more sensitive for early myeloid cells. * **Sodium Fluoride (NaF) Test:** If NSE positivity disappears after adding NaF, it confirms monocytic origin (M4/M5). If it persists, it may indicate megakaryocytic or other origins. Infiltration of the gums and skin is also characteristic of monocytic types of AML [2]. **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. 620-622. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 608-610.

Question 193: A patient presents with anemia and thrombocytopenia, and peripheral blood smear shows neutrophils with inclusions. What is the most probable diagnosis?

A. May-Hegglin anomaly (Correct Answer)
B. Evans syndrome
C. Alder-Reilly anomaly
D. Pelger-Huet anomaly

Explanation: **Explanation:** The correct answer is **May-Hegglin anomaly**. This is an autosomal dominant disorder caused by a mutation in the **MYH9 gene**, which encodes the non-muscle myosin heavy chain IIA. It is characterized by a classic triad: 1. **Thrombocytopenia** (leading to bleeding tendencies). 2. **Giant Platelets** (macrothrombocytopenia). 3. **Döhle-like inclusions** in the cytoplasm of neutrophils (large, blue-staining bodies composed of precipitated RNA and ribosomes). **Analysis of Incorrect Options:** * **Evans syndrome:** This is an autoimmune condition defined by the simultaneous or sequential occurrence of Immune Thrombocytopenic Purpura (ITP) and Autoimmune Hemolytic Anemia (AIHA). It does not feature specific neutrophil inclusions. * **Alder-Reilly anomaly:** This is associated with Mucopolysaccharidoses (e.g., Hurler syndrome). It features large, coarse, dark purple granules (azurophilic granules) in all types of leukocytes, not just neutrophils. * **Pelger-Huet anomaly:** This is a benign condition (or seen in myelodysplasia as "pseudo-Pelger-Huet") characterized by hyposegmentation of neutrophil nuclei (pince-nez appearance), but it does not present with thrombocytopenia or cytoplasmic inclusions [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Döhle bodies vs. May-Hegglin inclusions:** While they look similar, true Döhle bodies are seen in infections/burns (toxic changes), whereas May-Hegglin inclusions are larger and present even in the absence of infection. * **MYH9-related disorders:** This spectrum also includes Sebastian, Fechtner, and Epstein syndromes, which may feature additional findings like sensorineural deafness and nephritis. * **Diagnosis:** Often suspected when a patient has a low platelet count on automated counters (due to giant platelets being miscounted as RBCs) but shows large platelets on a peripheral smear [2]. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 613-614. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Red Blood Cell and Bleeding Disorders, pp. 666-667.

Question 194: A 30-year-old female patient presents with weakness and fatigue. Physical examination reveals koilonychia and pale mucous membranes. She also gives a history of irregular and heavy menstruation. The peripheral blood smear will most likely show anemia of which kind?

A. Microcytic and hypochromic. (Correct Answer)
B. Normocytic and normochromic.
C. Macrocytic and normochromic.
D. Macrocytic and hypochromic.

Explanation: ### Explanation **1. Why Option A is Correct:** The clinical presentation points toward **Iron Deficiency Anemia (IDA)**. The patient exhibits classic signs of chronic iron depletion: **koilonychia** (spoon-shaped nails) [1] and pallor. The history of **menorrhagia** (heavy menstruation) is the most common cause of IDA in reproductive-age females [3]. Pathophysiologically, iron is essential for heme synthesis. When iron stores are depleted, hemoglobin production decreases. To compensate for the lack of hemoglobin, erythroid precursors undergo additional divisions, resulting in smaller cells (**Microcytic**, MCV <80 fL) [2]. These cells contain less hemoglobin, leading to increased central pallor (**Hypochromic**, MCHC <32%) [2]. **2. Why Other Options are Incorrect:** * **Option B (Normocytic Normochromic):** This is typical of acute blood loss, anemia of chronic disease (early stages), or hemolytic anemias. While the patient has blood loss, it is *chronic*, leading to nutrient depletion and microcytosis. * **Option C (Macrocytic Normochromic):** This is characteristic of Megaloblastic Anemia (Vitamin B12 or Folate deficiency). It presents with hypersegmented neutrophils and macro-ovalocytes, not koilonychia. * **Option D (Macrocytic Hypochromic):** This is a rare morphology, sometimes seen in sideroblastic anemia or certain myelodysplastic syndromes, but it does not fit the clinical profile of iron loss. **3. NEET-PG High-Yield Pearls:** * **Earliest Lab Finding in IDA:** Decreased **Serum Ferritin** (most sensitive/specific marker). * **Earliest Morphological Change:** Increased **RDW** (Anisocytosis) [2]. * **Classic Triad (Plummer-Vinson Syndrome):** IDA, esophageal webs, and atrophic glossitis. * **Pencil Cells:** Characteristically seen on the peripheral smear in IDA [2]. * **Mentzer Index:** (MCV/RBC count) <13 suggests Thalassemia trait; >13 suggests IDA. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 576-577. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 590-591. [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 195: Which of the following is a characteristic feature of chronic myeloid leukemia (CML)?

A. Auer rods
B. Basophilia (Correct Answer)
C. Increased LAP score
D. Bone marrow fibrosis

Explanation: **Explanation:** **Chronic Myeloid Leukemia (CML)** is a myeloproliferative neoplasm characterized by the uncontrolled proliferation of the myeloid lineage, specifically due to the **t(9;22) Philadelphia chromosome**, which creates the *BCR-ABL1* fusion gene with constitutive tyrosine kinase activity [1]. **Why Basophilia is Correct:** Basophilia (an absolute increase in basophil count) is a hallmark feature of CML. It is often one of the earliest clues on a peripheral smear. A rising basophil count is clinically significant as it often signals disease progression toward the **Accelerated Phase** or **Blast Crisis**. **Analysis of Incorrect Options:** * **Auer Rods:** These are needle-like cytoplasmic inclusions seen in myeloblasts, characteristic of **Acute Myeloid Leukemia (AML)**, particularly the M3 subtype. They are absent in the chronic phase of CML. * **Increased LAP Score:** In CML, the **Leukocyte Alkaline Phosphatase (LAP) score is characteristically low or zero**, reflecting the functional immaturity of the proliferating neutrophils. A high LAP score is seen in Leukemoid Reactions or Polycythemia Vera. * **Bone Marrow Fibrosis:** While some reticulin fibrosis can occur in late-stage CML, it is the defining feature of **Primary Myelofibrosis (PMF)**, not a primary diagnostic characteristic of CML [2]. **High-Yield Clinical Pearls for NEET-PG:** * **Peripheral Smear:** Shows a "garden party" appearance (cells of all stages of maturation: myeloblasts to segmented neutrophils) [3]. * **Bimodal Peak:** Characteristically shows a peak in myelocytes and segmented neutrophils (the "myelocyte bulge"). * **Drug of Choice:** Imatinib (a Tyrosine Kinase Inhibitor) [3]. * **Most Common Physical Finding:** Splenomegaly (often massive) [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. 624-626. [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. 628-629. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 611-612.

Question 196: Schistocytes are seen in which condition?

A. Hemolytic Uremic Syndrome (HUS) (Correct Answer)
B. Henoch-Schönlein Purpura (HSP)
C. Abetalipoproteinemia
D. Myelofibrosis

Explanation: **Explanation:** **Schistocytes** (fragmented red blood cells) are the hallmark of **Microangiopathic Hemolytic Anemia (MAHA)** [1]. In conditions like **Hemolytic Uremic Syndrome (HUS)**, the underlying pathology involves the formation of microthrombi within small blood vessels [2]. As RBCs attempt to squeeze through these partially occluded vessels, they are mechanically sheared by fibrin strands, resulting in fragmented shapes like "helmet cells" or "triangle cells." **Analysis of Options:** * **A. Hemolytic Uremic Syndrome (HUS) (Correct):** Characterized by the triad of MAHA, thrombocytopenia, and acute kidney injury [1]. The mechanical fragmentation of RBCs in the renal microvasculature leads to prominent schistocytes on the peripheral smear [1]. * **B. Henoch-Schönlein Purpura (HSP):** This is an IgA-mediated small-vessel vasculitis. While it involves vessels, it does not typically cause the intravascular fibrin deposition required to produce schistocytes. * **C. Abetalipoproteinemia:** This condition is classically associated with **Acanthocytes** (spur cells) due to abnormalities in the RBC membrane lipids, not fragmentation. * **D. Myelofibrosis:** The characteristic finding here is **Dacrocytes** (tear-drop cells), which occur as RBCs are squeezed out of a fibrotic bone marrow. **High-Yield Clinical Pearls for NEET-PG:** * **MAHA Spectrum:** Schistocytes are also seen in TTP (Thrombotic Thrombocytopenic Purpura), DIC (Disseminated Intravascular Coagulation), and Malignant Hypertension [2]. * **Artificial Valves:** Mechanical heart valves can also cause schistocytes (Macroangiopathic hemolytic anemia). * **Morphology:** A peripheral smear must usually show **>1% schistocytes** to be clinically significant for MAHA. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Diseases Of The Urinary And Male Genital Tracts, pp. 540-541. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Red Blood Cell and Bleeding Disorders, pp. 667-668.

Question 197: Pernicious anemia occurs due to:

A. Failure of secretion of Vitamin B12
B. Failure of secretion of intrinsic factor (Correct Answer)
C. Failure of absorption of intrinsic factor
D. Folate deficiency

Explanation: **Explanation:** **Pernicious Anemia (PA)** is a specific type of megaloblastic anemia caused by an autoimmune gastritis that leads to the destruction of gastric parietal cells [1], [2]. 1. **Why Option B is Correct:** Gastric parietal cells are responsible for secreting **Intrinsic Factor (IF)** [2]. IF is essential for the absorption of Vitamin B12 in the terminal ileum. In PA, the body produces autoantibodies (Type I, II, and III) against parietal cells and IF itself [1], [3]. The resulting failure of IF secretion leads to Vitamin B12 malabsorption, even if dietary intake is adequate [1], [5]. 2. **Why Other Options are Incorrect:** * **Option A:** Vitamin B12 is not "secreted" by the body; it is an essential nutrient obtained from dietary sources (animal products). * **Option C:** Intrinsic factor is not absorbed; it acts as a carrier protein. It is the **B12-IF complex** that is absorbed in the terminal ileum via cubilin receptors [3]. * **Option D:** While folate deficiency also causes megaloblastic anemia, it is etiologically distinct from Pernicious Anemia and does not involve intrinsic factor pathology [5]. **High-Yield Clinical Pearls for NEET-PG:** * **Triad of PA:** Megaloblastic anemia, Atrophic glossitis (Hunter’s glossitis), and Neurological symptoms (Subacute Combined Degeneration of the spinal cord) [4]. * **Diagnostic Markers:** Anti-parietal cell antibodies (more sensitive) and Anti-intrinsic factor antibodies (more specific) [1]. * **Morphology:** Peripheral smear shows **macro-ovalocytes** and **hypersegmented neutrophils** (>5 lobes). * **Increased Risk:** Patients with PA have a 3x increased risk of developing **Gastric Adenocarcinoma** and Carcinoid tumors due to chronic achlorhydria and hypergastrinemia [2]. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 592-593. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, pp. 771-772. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Red Blood Cell and Bleeding Disorders, pp. 655-656. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, pp. 772-773. [5] 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. 130-131.

Question 198: Thrombocytopenia is not seen in which of the following conditions?

A. Henoch-Schönlein purpura (Correct Answer)
B. Disseminated intravascular coagulation (DIC)
C. Leukemia
D. Metastasis

Explanation: **Explanation:** The correct answer is **Henoch-Schönlein purpura (HSP)** because it is a condition characterized by **non-thrombocytopenic purpura**. **1. Why Henoch-Schönlein purpura (HSP) is correct:** HSP is a small-vessel vasculitis mediated by **IgA immune complex deposition** in the vessel walls. The purpuric rash occurs due to inflammation and increased capillary fragility (leukocytoclastic vasculitis), not due to a lack of platelets. In fact, a normal or even elevated platelet count is a diagnostic hallmark that helps distinguish HSP from other causes of purpura like ITP or leukemia. **2. Why the other options are incorrect:** * **Disseminated Intravascular Coagulation (DIC):** This is a consumptive coagulopathy. Widespread activation of the coagulation cascade leads to the "consumption" of platelets and clotting factors, resulting in profound thrombocytopenia [3]. * **Leukemia:** Malignant proliferation of white blood cells in the bone marrow leads to "marrow crowding" or myelophthisis. This suppresses normal hematopoiesis, resulting in decreased production of megakaryocytes and subsequent thrombocytopenia [1]. * **Metastasis:** Solid tumor infiltration into the bone marrow (e.g., from breast, lung, or prostate cancer) causes myelophthisic anemia. The replacement of healthy marrow space by metastatic cells impairs platelet production [1]. **Clinical Pearls for NEET-PG:** * **HSP Tetrad:** Palpable purpura (usually on buttocks/legs), arthralgia, abdominal pain (intussusception risk), and renal disease (IgA nephropathy). * **Platelet Count in HSP:** Always **Normal**. * **Rule of Thumb:** If a question mentions "palpable purpura" with a normal platelet count, think of Vasculitis (like HSP). If the purpura is "flat/non-palpable" with a low platelet count, think of Thrombocytopenia [2]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Red Blood Cell and Bleeding Disorders, pp. 665-666. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 620-621. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Red Blood Cell and Bleeding Disorders, pp. 667-668.

Question 199: A child presents with spontaneous bleeding into the joint. Investigations reveal a prolonged aPTT and decreased levels of factor VIII. What is the likely inheritance pattern of this disease?

A. Autosomal dominant
B. Autosomal recessive
C. X-linked recessive (Correct Answer)
D. X-linked dominant

Explanation: **Explanation:** The clinical presentation of spontaneous hemarthrosis (bleeding into joints), a prolonged activated Partial Thromboplastin Time (aPTT), and a deficiency of Factor VIII is diagnostic of **Hemophilia A**. [1] **1. Why X-linked Recessive is correct:** Hemophilia A is caused by a mutation in the *F8* gene located on the **X chromosome**. [1] Because it follows an **X-linked recessive** inheritance pattern, the disease primarily affects males (who have only one X chromosome), while females are typically asymptomatic carriers. [2] A prolonged aPTT reflects a defect in the intrinsic pathway of the coagulation cascade, where Factor VIII serves as a critical cofactor for Factor IX. **2. Why other options are incorrect:** * **Autosomal Dominant:** Conditions like Von Willebrand Disease (Type 1 and 2) follow this pattern. While VWD can involve low Factor VIII, it typically presents with mucosal bleeding (epistaxis, menorrhagia) rather than deep-seated joint bleeds. * **Autosomal Recessive:** Rare clotting factor deficiencies (e.g., Factor VII, X, or XI) follow this pattern. Factor XI deficiency (Hemophilia C) causes a prolonged aPTT but is not X-linked. * **X-linked Dominant:** This is rare in hematology (e.g., Alport syndrome can be XLD). In this pattern, both males and females would be symptomatic in every generation, which does not fit the classic epidemiology of Hemophilia. **High-Yield Clinical Pearls for NEET-PG:** * **Hemophilia A:** Factor VIII deficiency (X-linked Recessive). [1] * **Hemophilia B (Christmas Disease):** Factor IX deficiency (X-linked Recessive); clinically indistinguishable from Hemophilia A. * **Mixing Study:** In Hemophilia, a prolonged aPTT **corrects** when mixed with normal plasma (indicating a deficiency, not an inhibitor). * **Bleeding Time (BT):** Remains **normal** in Hemophilia (platelet function is intact), distinguishing it from VWD or platelet disorders. **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. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Genetic Disorders, p. 151.

Question 200: All of the following are true about parahemophilia except?

A. Due to Factor V deficiency
B. X-linked recessive inheritance (Correct Answer)
C. Prolonged activated partial thromboplastin time (aPTT) and prothrombin time (PT)
D. All are true

Explanation: **Explanation:** **Parahemophilia** (also known as Owren’s disease) is a rare bleeding disorder caused by a deficiency of **Coagulation Factor V** [1]. 1. **Why Option B is the correct answer (The "Except"):** Parahemophilia follows an **Autosomal Recessive** inheritance pattern, not X-linked recessive. Unlike Hemophilia A (Factor VIII) and Hemophilia B (Factor IX), which are X-linked and primarily affect males [1], parahemophilia affects both sexes equally. 2. **Analysis of other options:** * **Option A:** True. Parahemophilia is specifically defined as a congenital deficiency of Factor V, a cofactor necessary for the conversion of prothrombin to thrombin [3]. * **Option C:** True. Factor V is a key component of the **Common Pathway** of the coagulation cascade [3]. Because it affects the common pathway, both the **Prothrombin Time (PT)** and the **activated Partial Thromboplastin Time (aPTT)** are prolonged [2]. The Bleeding Time (BT) is usually normal. **High-Yield Clinical Pearls for NEET-PG:** * **Factor V Role:** It acts as a cofactor for Factor Xa in the "Prothrombinase complex" [3]. * **Clinical Presentation:** Ranges from mild mucosal bleeding (epistaxis, menorrhagia) to severe post-surgical hemorrhage [2]. * **Treatment:** Since there is no purified Factor V concentrate available, the treatment of choice is **Fresh Frozen Plasma (FFP)**. * **Differential Diagnosis:** Do not confuse Parahemophilia with **Factor V Leiden**. While Parahemophilia is a *deficiency* leading to bleeding [2], Factor V Leiden is a *mutation* causing resistance to Protein C, leading to thrombophilia (clotting) [3]. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 622-623. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 625-626. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 582-583.

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Thrombotic Disorders

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