Hematopathology — MCQs
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What is the biochemical marker of lymphocytic leukemia?
Alpha thalassemia is due to which of the following?
A 15-year-old boy presented with a one-day history of bleeding gums, subconjunctival bleed, and purpuric rash. Investigations revealed the following results: Hb-6.4 gm/dL, TLC-26,500/mm3, Platelet - 35,000 mm3, Prothrombin time-20 sec (control of 13 sec), Partial thromboplastin time-50 sec, and Fibrinogen 10 mg/dl. Peripheral smear was suggestive of acute myeloblastic leukemia. Which of the following is the most likely diagnosis?
Which functional test assesses primary hemostasis?
Which laboratory test is considered the gold standard for diagnosing Paroxysmal Nocturnal Hemoglobinuria (PNH)?
What is the most common cause of beta thalassemia?
Schistocytes are found in all of the following conditions EXCEPT?
Which of the following is the most important prognostic factor in ALL?
All of the following are true regarding the diagnosis of hemolytic anemia except:
Cabot's ring is seen in which of the following conditions?
Hematopathology Indian Medical PG Practice Questions and MCQs
Question 711: What is the biochemical marker of lymphocytic leukemia?
- A. Enolase
- B. Peroxidase
- C. Choline esterase
- D. Periodic acid-Schiff (PAS) stain (Correct Answer)
Explanation: **Explanation:** In the context of Acute Lymphoblastic Leukemia (ALL), the **Periodic acid-Schiff (PAS) stain** is a classic biochemical marker used to identify lymphoblasts. The underlying medical concept is the presence of large aggregates of **glycogen** within the cytoplasm of neoplastic lymphocytes. When stained with PAS, these cells exhibit a characteristic **"block-like" or "chunky" positivity**, which helps differentiate them from myeloblasts [1]. **Analysis of Options:** * **A. Enolase:** Specifically, Neuron-Specific Enolase (NSE) is a marker for neuroendocrine tumors (like Small Cell Carcinoma) and certain myeloid leukemias (Monocytic lineage), but not a primary marker for lymphocytic leukemia. * **B. Peroxidase (Myeloperoxidase/MPO):** This is the hallmark marker for **Acute Myeloid Leukemia (AML)**. It is found in the primary granules of myeloid cells. Lymphoblasts are characteristically MPO-negative [1]. * **C. Choline esterase:** While acetylcholinesterase can be found in certain blood cells (like RBCs and megakaryocytes), it is not used as a diagnostic biochemical marker for lymphocytic leukemia. **High-Yield Clinical Pearls for NEET-PG:** * **ALL Staining Pattern:** PAS positivity in ALL is described as "chunky" or "globular," unlike the diffuse staining seen in other cells [1]. * **MPO vs. Sudan Black B (SBB):** Both are markers for AML. If a cell is MPO positive, it is myeloid; if it is PAS chunky positive and MPO negative, it is likely lymphoid. * **Gold Standard:** While PAS is a classic biochemical/histochemical marker, **Immunophenotyping (Flow Cytometry)** for markers like TdT, CD10 (CALLA), CD19, and CD3 is the modern gold standard for diagnosing and subtyping ALL [1]. * **TdT (Terminal Deoxynucleotidyl Transferase):** A specialized DNA polymerase that is a highly specific nuclear marker for lymphoblasts (present in 95% of ALL) [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. 599-602.
Question 712: Alpha thalassemia is due to which of the following?
- A. Alpha chain deficiency (Correct Answer)
- B. Alpha chain excess
- C. Beta chain deficiency
- D. Beta chain excess
Explanation: **Explanation:** **Core Concept:** Thalassemia is a quantitative hemoglobinopathy characterized by a **reduced rate of synthesis** of one or more globin chains [1]. In **Alpha (α) Thalassemia**, there is a partial or total deficiency in the production of alpha-globin chains, usually due to gene deletions on Chromosome 16 [2]. Since normal adult hemoglobin (HbA) consists of $\alpha_2\beta_2$, a deficiency in alpha chains leads to an overall reduction in hemoglobin synthesis, resulting in microcytic hypochromic anemia. **Analysis of Options:** * **Option A (Correct):** Alpha thalassemia is defined by the **deficiency** of alpha-globin chains. * **Option B (Incorrect):** Alpha chain excess is not the primary defect; however, in Beta thalassemia, a relative excess of alpha chains occurs, which precipitates and causes hemolysis. * **Option C (Incorrect):** Beta chain deficiency is the hallmark of **Beta Thalassemia**, not alpha. * **Option D (Incorrect):** In Alpha thalassemia, because alpha chains are deficient, there is a **relative excess of beta chains** (in adults) or gamma chains (in neonates). These excess chains form tetramers ($ \beta_4 $ known as HbH, and $ \gamma_4 $ known as Hb Bart's). **High-Yield Clinical Pearls for NEET-PG:** * **Genetics:** Alpha thalassemia is most commonly due to **gene deletions** (unlike Beta thalassemia, which is usually due to point mutations). * **Hb Bart’s ($\gamma_4$):** Seen in Hydrops Fetalis (deletion of all 4 alpha genes); it has an extremely high oxygen affinity, making it useless for oxygen delivery. * **HbH Disease ($\beta_4$):** Occurs when 3 alpha genes are deleted [2]. On a peripheral smear, "golf ball" inclusions (denatured HbH) can be seen with supravital stains like Brilliant Cresyl Blue [1]. * **Diagnosis:** Unlike Beta thalassemia, HbA2 levels are typically **normal or low** in Alpha thalassemia trait [2]. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 587-588, 600-601. [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.
Question 713: A 15-year-old boy presented with a one-day history of bleeding gums, subconjunctival bleed, and purpuric rash. Investigations revealed the following results: Hb-6.4 gm/dL, TLC-26,500/mm3, Platelet - 35,000 mm3, Prothrombin time-20 sec (control of 13 sec), Partial thromboplastin time-50 sec, and Fibrinogen 10 mg/dl. Peripheral smear was suggestive of acute myeloblastic leukemia. Which of the following is the most likely diagnosis?
- A. Myeloblastic leukemia without maturation
- B. Myeloblastic leukemia with maturation
- C. Promyelocytic leukemia (Correct Answer)
- D. Myelomonocytic leukemia
Explanation: The clinical presentation of a young patient with sudden onset bleeding (gums, subconjunctival, purpura) combined with significant laboratory abnormalities—**prolonged PT/aPTT and severe hypofibrinogenemia (10 mg/dL)**—is pathognomonic for **Disseminated Intravascular Coagulation (DIC)** [1]. **1. Why Promyelocytic Leukemia (APL) is correct:** Acute Promyelocytic Leukemia (AML-M3) is uniquely associated with a high incidence of DIC [4]. The malignant promyelocytes contain numerous primary granules and **Auer rods** (often in bundles called 'Faggot cells') [2]. These granules release **tissue factor-like procoagulants** and fibrinolytic enzymes into the circulation, triggering a consumptive coagulopathy. This is a medical emergency requiring immediate treatment with ATRA (All-Trans Retinoic Acid). **2. Why other options are incorrect:** * **Option A (M1) & B (M2):** While these are common forms of AML, they typically present with features of bone marrow failure (anemia, infections). They do not characteristically present with primary DIC or such profound hypofibrinogenemia. * **Option D (M4):** Myelomonocytic leukemia is characterized by both myeloid and monocytic differentiation [4]. It is more commonly associated with **extramedullary involvement** (e.g., gingival hypertrophy or CNS involvement) rather than acute DIC. **3. Clinical Pearls for NEET-PG:** * **Cytogenetics:** APL is associated with **t(15;17)**, involving the *PML-RARα* fusion gene [3]. * **Morphology:** Look for "Faggot cells" (cells with bundles of Auer rods) in the peripheral smear or marrow [4]. * **Treatment:** ATRA and Arsenic Trioxide. Beware of **Differentiation Syndrome** as a complication of treatment. * **Key Lab Clue:** In any AML question, if **Fibrinogen is low** or **D-dimer is high**, always prioritize APL (M3). **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Red Blood Cell and Bleeding Disorders, pp. 672-673. [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. 621-622. [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. 620-621. [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. 620.
Question 714: Which functional test assesses primary hemostasis?
- A. Bleeding time (Correct Answer)
- B. Activated partial thromboplastin time
- C. Platelet count
- D. Prothrombin time
Explanation: **Explanation:** Hemostasis occurs in two main phases: **Primary hemostasis** (formation of the platelet plug) and **Secondary hemostasis** (activation of the coagulation cascade to form fibrin) [2]. **Why Bleeding Time (BT) is correct:** Bleeding time is a **functional test** that measures the time taken for a standardized skin puncture to stop bleeding. It specifically assesses the interaction between the vessel wall and platelets [1]. It is prolonged in conditions affecting primary hemostasis, such as **thrombocytopenia** (low count), **thrombocytopathy** (functional defects like Glanzmann thrombasthenia), or **von Willebrand Disease (vWD)** [1],[3]. **Why other options are incorrect:** * **Platelet Count:** While essential, this is a **quantitative** test, not a functional one [1]. A patient can have a normal platelet count but abnormal primary hemostasis due to functional defects. * **Prothrombin Time (PT):** This assesses the **extrinsic and common pathways** of secondary hemostasis (Factors VII, X, V, II, and I). * **Activated Partial Thromboplastin Time (aPTT):** This assesses the **intrinsic and common pathways** of secondary hemostasis (Factors XII, XI, IX, VIII, X, V, II, and I). **High-Yield Clinical Pearls for NEET-PG:** * **vWD:** This is the most common inherited bleeding disorder. It uniquely shows a **prolonged BT** (primary defect) and often a **prolonged aPTT** (secondary defect, as vWF stabilizes Factor VIII). * **Normal BT:** 2–7 minutes (Ivy’s method). * **Drug Effect:** Aspirin irreversibly inhibits COX-1, prolonging BT for the lifespan of the platelet (approx. 7–10 days). * **PFA-100:** In modern labs, the Platelet Function Analyzer (PFA-100) is increasingly replacing the manual Bleeding Time test for better sensitivity and reproducibility [4]. **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] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 581-582. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Red Blood Cell and Bleeding Disorders, pp. 668-669. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Red Blood Cell and Bleeding Disorders, pp. 664-665.
Question 715: Which laboratory test is considered the gold standard for diagnosing Paroxysmal Nocturnal Hemoglobinuria (PNH)?
- A. Ham test
- B. Haptoglobin
- C. Flow cytometry (Correct Answer)
- D. Sucrose Lysis test
Explanation: **Explanation:** **Paroxysmal Nocturnal Hemoglobinuria (PNH)** is an acquired clonal hematopoietic stem cell disorder caused by a somatic mutation in the **PIGA gene**. This mutation leads to a deficiency of Glycosylphosphatidylinositol (GPI) anchors, which are necessary to attach protective proteins like **CD55** (Decay Accelerating Factor) and **CD59** (Membrane Inhibitor of Reactive Lysis) to the cell membrane [1]. Without these, cells are highly susceptible to complement-mediated lysis. **Why Flow Cytometry is the Gold Standard:** Flow cytometry is the most sensitive and specific test. It directly detects the absence or reduction of GPI-anchored proteins (CD55 and CD59) on the surface of red blood cells, neutrophils, and monocytes [1]. The use of **FLAER (Fluorescent-labeled Aerolysin)**, which binds specifically to the GPI anchor itself, has further increased the sensitivity, especially for detecting small PNH clones. **Analysis of Incorrect Options:** * **Ham Test (Acidified Serum Test):** Historically used, it relies on the fact that PNH cells lyse in acidified serum. It is now obsolete due to low sensitivity and high complexity. * **Sucrose Lysis Test:** A screening test where PNH cells lyse in low-ionic-strength sucrose solutions. It has a high false-positive rate and is no longer recommended for definitive diagnosis. * **Haptoglobin:** This is a marker of intravascular hemolysis (levels will be decreased) [2]. While helpful in supporting a diagnosis of hemolytic anemia, it is non-specific and cannot diagnose PNH. **High-Yield Clinical Pearls for NEET-PG:** * **Classic Triad:** Hemolytic anemia, pancytopenia, and venous thrombosis (often in unusual sites like the Budd-Chiari syndrome) [1]. * **PNH and Malignancy:** PNH can evolve into Aplastic Anemia or Acute Myeloid Leukemia (AML). * **Treatment:** **Eculizumab**, a monoclonal antibody against complement protein C5, is the drug of choice to prevent hemolysis. **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] 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 716: What is the most common cause of beta thalassemia?
- A. Mutations leading to aberrant RNA splicing. (Correct Answer)
- B. Mutations lie within the β-globin promoter and lower the rate of β-globin gene transcription.
- C. Mutations involve the coding regions of the β-globin gene.
- D. All of the above are equally common.
Explanation: **Explanation:** Beta-thalassemia is a heterogeneous group of genetic disorders characterized by reduced ($̢^+$) or absent ($̢^0$) synthesis of ̢-globin chains. Unlike ̡-thalassemia, which is primarily caused by gene deletions [1], **̢-thalassemia is almost always caused by point mutations** [1], [3]. **1. Why Option A is correct:** The most common molecular mechanism leading to ̢-thalassemia involves **mutations that affect RNA splicing** [3]. These mutations typically occur within introns or at exon-intron junctions [2]. They can either destroy normal splice sites or create "cryptic" splice sites, leading to the production of abnormal mRNA transcripts that are degraded before translation [2]. This results in a significant deficit of functional ̢-globin [1]. **2. Analysis of Incorrect Options:** * **Option B:** Promoter region mutations (e.g., TATA box mutations) do occur and lead to reduced transcription, but they are less frequent than splicing mutations and typically result in a milder (̢^+) phenotype [1], [2]. * **Option C:** Mutations in coding regions (like chain termination mutations or frameshifts) lead to ̢^0 thalassemia [2]. While clinically severe, they are statistically less common than splicing defects [3]. * **Option D:** The distribution is not equal; splicing defects represent the majority of cases globally [3]. **High-Yield Clinical Pearls for NEET-PG:** * **Molecular Basis:** ̡-Thalassemia = Deletions; ̢-Thalassemia = Point Mutations [1]. * **Peripheral Smear:** Microcytic hypochromic anemia with **Target cells** and **Basophilic stippling**. * **Diagnosis:** Gold standard is **Hb Electrophoresis/HPLC**, showing increased **HbA2 (>3.5%)** and increased HbF. * **Complication:** Secondary Hemochromatosis (iron overload) due to repeated transfusions and increased intestinal absorption. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Red Blood Cell and Bleeding Disorders, p. 650. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Genetic Disorders, pp. 147-148. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Red Blood Cell and Bleeding Disorders, pp. 646-647.
Question 717: Schistocytes are found in all of the following conditions EXCEPT?
- A. Immune thrombocytopenic purpura (ITP) (Correct Answer)
- B. Severe iron deficiency anemia
- C. March hemoglobinuria
- D. Disseminated intravascular coagulation (DIC)
Explanation: ### Explanation **Schistocytes** (fragmented RBCs) are the hallmark of **Microangiopathic Hemolytic Anemia (MAHA)** and mechanical trauma to erythrocytes [1]. They form when RBCs are sheared while passing through fibrin strands in microvessels or by mechanical impact [3]. **Why Option A is the Correct Answer:** **Immune Thrombocytopenic Purpura (ITP)** is an isolated consumption of platelets due to anti-platelet antibodies [4]. Crucially, there is **no activation of the coagulation cascade** and no fibrin mesh formation in the blood vessels. Since the RBCs do not encounter any physical obstruction or shearing force, schistocytes are **not** seen. The peripheral smear in ITP typically shows only thrombocytopenia with "giant" platelets (megathrombocytes) [4], [5]. **Analysis of Incorrect Options:** * **Disseminated Intravascular Coagulation (DIC):** This is a classic cause of MAHA. Widespread fibrin deposition in small vessels shears RBCs, leading to abundant schistocytes [1]. * **March Hemoglobinuria:** This is a form of traumatic hemolysis caused by repetitive physical impact (e.g., long-distance running on hard surfaces). The mechanical force ruptures RBCs in the capillaries of the feet, producing fragmented cells. * **Severe Iron Deficiency Anemia:** In advanced stages, RBCs become extremely fragile and "pencil-shaped." These fragile cells can fragment easily, leading to the presence of schistocytes on the smear. **NEET-PG High-Yield Pearls:** 1. **The "MAHA" Pentad:** Schistocytes are most characteristically seen in TTP (Thrombotic Thrombocytopenic Purpura), HUS (Hemolytic Uremic Syndrome), and DIC [1], [2]. 2. **Helmet Cells:** Another name for schistocytes due to their characteristic appearance. 3. **Artificial Valves:** Mechanical heart valves are a common "macroangiopathic" cause of schistocytes. 4. **Differential Diagnosis:** If you see schistocytes + low platelets, think TTP/HUS/DIC. If you see low platelets + normal RBC morphology, think ITP. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Red Blood Cell and Bleeding Disorders, pp. 667-668. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Kidney, pp. 947-948. [3] 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. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Red Blood Cell and Bleeding Disorders, pp. 666-667. [5] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 620-621.
Question 718: Which of the following is the most important prognostic factor in ALL?
- A. Hyperdiploidy
- B. Total leukocyte count greater than 50,000
- C. Age
- D. Response to steroids (Correct Answer)
Explanation: **Explanation:** In Acute Lymphoblastic Leukemia (ALL), while several factors contribute to the initial risk stratification, the **response to induction therapy** (specifically the early response to steroids and chemotherapy) is the **most important independent prognostic factor**. [1] **1. Why "Response to steroids" is correct:** The initial response to therapy is a functional "in-vivo" test of the tumor's sensitivity to treatment. A "steroid prophase" is often used; a poor response (defined as a peripheral blast count >1000/µL after 7 days of prednisone) indicates a significantly higher risk of relapse and poor survival, regardless of the initial genetic or clinical features. This has largely been superseded in modern protocols by **Minimal Residual Disease (MRD)** monitoring, but the principle remains: how the disease reacts to drugs is the ultimate prognostic indicator. [1] **2. Analysis of Incorrect Options:** * **Age (C):** While age is a major prognostic factor (favorable: 2–10 years; poor: <2 years or >10 years), it is a baseline characteristic that can be overcome by modern intensive therapy. [1] * **Total Leukocyte Count (B):** A TLC >100,000/µL is a poor prognostic marker, but like age, it is a static baseline feature. [1] * **Hyperdiploidy (A):** This is a **cytogenetic** factor associated with a *favorable* prognosis, but it is not the "most important" compared to treatment response. [1] **Clinical Pearls for NEET-PG:** * **Best Prognostic Cytogenetics:** t(12;21) [ETV6-RUNX1] and Hyperdiploidy (>50 chromosomes). [1] * **Worst Prognostic Cytogenetics:** t(9;22) [Philadelphia chromosome], t(4;11) [KMT2A rearrangement], and Hypodiploidy. [1] * **Immunophenotype:** B-ALL generally has a better prognosis than T-ALL. * **CNS Involvement:** Presence of blasts in CSF at diagnosis is a poor prognostic sign. **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. 599-602.
Question 719: All of the following are true regarding the diagnosis of hemolytic anemia except:
- A. Elevated unconjugated bilirubin in the blood
- B. Low lactate dehydrogenase (LDH) in the blood (Correct Answer)
- C. Haptoglobin levels are decreased
- D. Direct Coombs test is positive
Explanation: **Explanation:** Hemolytic anemia is characterized by the premature destruction of red blood cells (RBCs). To identify the "except" option, we must understand the biochemical markers of increased RBC turnover. **1. Why "Low LDH" is the correct answer (The False Statement):** Lactate Dehydrogenase (LDH) is an enzyme found in high concentrations inside erythrocytes. When RBCs lyse (hemolysis), LDH is released into the serum. Therefore, **elevated LDH**, not low LDH, is a hallmark marker of hemolysis. It serves as a sensitive indicator of the magnitude of cell destruction. **2. Analysis of Incorrect Options (True Statements):** * **Elevated unconjugated bilirubin:** When RBCs break down, hemoglobin is metabolized. The heme portion is converted into unconjugated (indirect) bilirubin [1]. If the liver's conjugating capacity is exceeded, serum unconjugated bilirubin rises, often leading to acholuric jaundice. * **Decreased Haptoglobin:** Haptoglobin is a plasma protein that binds to free hemoglobin released during intravascular hemolysis [1]. The hemoglobin-haptoglobin complexes are rapidly cleared by the liver, leading to a significant drop in measurable serum haptoglobin levels. * **Positive Direct Coombs Test:** This test detects antibodies or complement bound directly to the surface of RBCs. It is the gold standard for diagnosing **Autoimmune Hemolytic Anemia (AIHA)**, a major subtype of hemolytic anemia [2]. **Clinical Pearls for NEET-PG:** * **Intravascular vs. Extravascular:** Low haptoglobin and hemoglobinuria are more prominent in *intravascular* hemolysis (e.g., G6PD deficiency, PNH) [1]. * **Reticulocytosis:** An elevated Reticulocyte Count (and high RPI) is the most common sign of the bone marrow's compensatory response to hemolysis [1]. * **Peripheral Smear:** Look for **Schistocytes** (fragmented cells) in microangiopathic hemolytic anemia (MAHA) and **Spherocytes** in Hereditary Spherocytosis or Warm AIHA [2], [3]. **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] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 602-603. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 597-598.
Question 720: Cabot's ring is seen in which of the following conditions?
- A. Megaloblastic anemia (Correct Answer)
- B. Sickle cell disease
- C. Iron deficiency anemia
- D. Autoimmune anemia
Explanation: **Explanation:** **Cabot’s Rings** are thin, red-purple, thread-like strands found inside red blood cells. They typically appear in the shape of a loop, a figure-of-eight, or a ring. **1. Why Megaloblastic Anemia is Correct:** Cabot’s rings are remnants of the **mitotic spindle** (microtubules) or remnants of the nuclear membrane. They occur in conditions characterized by **dyserythropoiesis** (defective red cell production). In Megaloblastic Anemia (Vitamin B12 or Folate deficiency), there is a defect in DNA synthesis leading to nuclear-cytoplasmic asynchrony [1]. This abnormal maturation results in nuclear remnants like Cabot’s rings and Howell-Jolly bodies being left behind in the cytoplasm [1]. **2. Why Other Options are Incorrect:** * **Sickle Cell Disease:** Characterized by sickle-shaped cells and Howell-Jolly bodies (due to autosplenectomy), but Cabot’s rings are not a classic hallmark. * **Iron Deficiency Anemia:** Typically shows microcytic hypochromic cells, pencil cells, and target cells. It does not involve the nuclear maturation defects required to form Cabot’s rings. * **Autoimmune Anemia:** Primarily presents with microspherocytes and polychromasia due to reticulocytosis, rather than nuclear remnants. **3. High-Yield Clinical Pearls for NEET-PG:** * **Differential Diagnosis:** Besides Megaloblastic anemia, Cabot’s rings are also seen in **Lead poisoning** (along with coarse basophilic stippling) and post-splenectomy states. * **Stain:** They are best visualized using **Romanowsky stains** (e.g., Leishman, Giemsa, or Wright stain). * **Mnemonic:** Remember **"C"** for **C**abot’s rings, **C**oarse basophilic stippling, and **C**yanide/Lead (Lead poisoning). **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 593-594.
Practice by Chapter
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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