Hematopathology Practice Questions

Q: Increased LAP score is seen in which of the following conditions?

Myelofibrosis. **Explanation:** The **Leukocyte Alkaline Phosphatase (LAP) score** (also known as the Neutrophil Alkaline Phosphatase/NAP score) measures the activity of the enzyme alkaline phosphatase within the secondary granules of mature neutrophils. It is a classic marker used to differentiate reactive leukocytosis from neoplastic processes [1]. **1. Why Myelofibrosis is Correct:** In **Myelofibrosis** (a Chronic Myeloproliferative Neoplasm), there is an increase in mature, functioning neutrophils [1], leading to an **elevated LAP score**. Other conditions causing an increased score include the Leukemoid reaction [1], Polycythemia Vera, pregnancy, and acute infections. **2. Analysis of Incorrect Options:** * **Chronic Myeloid Leukemia (CML):** This is the most high-yield contrast. In CML, the LAP score is **characteristically low** because the rapidly proliferating neoplastic cells are enzymatically deficient. * **Paroxysmal Nocturnal Hemoglobinuria (PNH):** This is a stem cell defect where cells lack GPI-anchored proteins. Since LAP is a GPI-anchored enzyme, its levels are **decreased** in PNH. * **Megaloblastic Anemia:** This condition typically presents with pancytopenia and hypersegmented neutrophils; however, the LAP score is generally **decreased** or normal. **High-Yield Clinical Pearls for NEET-PG:** * **LAP Score Range:** Normal range is typically **40–100**. * **Increased LAP (>100):** Leukemoid reaction [1], Myelofibrosis [1], Polycythemia Vera, Pregnancy, Cushing’s syndrome. * **Decreased LAP (<40):** CML (most common cause), PNH, Hypophosphatasia, Aplastic anemia, and AML. * **The "CML vs. Leukemoid" Rule:** If a patient has a high TLC and splenomegaly, a **low LAP** points to CML, while a **high LAP** points to a Leukemoid reaction [1]. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 580-616.

Q: Which subtype of Acute Myeloid Leukemia (AML) commonly causes gingival hypertrophy?

M4. **Explanation:** **Correct Answer: D (M4)** The correct answer is **M4 (Acute Myelomonocytic Leukemia)**. The underlying medical concept is the **monocytic lineage**. In the FAB classification, AML subtypes with a monocytic component—specifically **M4** and **M5 (Acute Monocytic Leukemia)**—are notorious for extramedullary infiltration [1]. Monoblasts and monocytes have a high propensity to migrate out of the blood vessels and infiltrate tissues such as the **gingiva (gums)**, skin (leukemia cutis), and central nervous system. Gingival hypertrophy occurs because these leukemic cells physically invade the submucosal connective tissue of the gums. **Analysis of Incorrect Options:** * **A (M1 - AML without maturation):** Characterized by poorly differentiated myeloblasts; tissue infiltration is rare. * **B (M2 - AML with maturation):** The most common subtype, often associated with t(8;21) [1]. While it can cause chloromas (granulocytic sarcomas), it does not typically present with gingival hyperplasia. * **C (M3 - Acute Promyelocytic Leukemia):** Associated with t(15;17). Its hallmark clinical presentation is **DIC (Disseminated Intravascular Coagulation)** due to the release of procoagulants from Auer rods, not tissue infiltration [1]. **High-Yield Clinical Pearls for NEET-PG:** * **M4/M5:** Look for "Gingival Hyperplasia" and "Negative Myeloperoxidase (MPO)" but **"Positive Non-Specific Esterase (NSE)"** stain. * **M3:** Associated with **Auer rods** (faggot cells) and the **PML-RARα** fusion gene [1]. Treatment involves ATRA (All-trans retinoic acid). * **M7:** Associated with Down Syndrome (in children <5 years) and acute myelofibrosis. * **M2:** Most common subtype overall; associated with **t(8;21)** and a relatively good prognosis [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.

Q: Increased fetal hemoglobin (HbF) is seen in which of the following conditions?

Juvenile CML. **Explanation:** The correct answer is **Juvenile CML (JMML)**. **1. Why Juvenile CML is correct:** Juvenile Myelomonocytic Leukemia (JMML), formerly known as Juvenile CML, is a rare clonal hematopoietic stem cell disorder of childhood. A hallmark feature of JMML is the **reversion to fetal erythropoiesis**, which leads to a significant increase in **Fetal Hemoglobin (HbF)** levels, often disproportionate to the child's age. This occurs because the malignant clone retains or reactivates the program for fetal hemoglobin production. **2. Analysis of Incorrect Options:** * **Congenital red cell aplasia (Diamond-Blackfan Anemia):** While HbF can be elevated in this condition as a stress response to erythroid marrow failure, it is not the primary diagnostic hallmark compared to the classic association with JMML in the context of myeloproliferative disorders. * **Hereditary Spherocytosis:** This is a red cell membrane defect leading to extravascular hemolysis. It does not involve a switch in hemoglobin synthesis; therefore, HbF levels remain normal. * **AML (Acute Myeloid Leukemia):** While some cases of erythroleukemia (M6) may show minor elevations in HbF, it is not a consistent or characteristic finding for AML as a whole. **Clinical Pearls for NEET-PG:** * **JMML Triad:** Hepatosplenomegaly, lymphadenopathy, and skin rash in a child <2 years. * **Laboratory Markers for JMML:** Increased HbF, absence of Philadelphia chromosome ($t(9;22)$), and hypersensitivity of myeloid progenitors to GM-CSF. * **Other conditions with high HbF:** Beta-thalassemia major, Sickle cell anemia (compensatory), and Hereditary Persistence of Fetal Hemoglobin (HPFH).

Q: Leukocyte common antigen (CD45) is typically seen in which of the following malignancies?

Lymphoma. **Explanation:** **Leukocyte Common Antigen (CD45)** is a transmembrane glycoprotein found on the surface of almost all **hematopoietic cells** and their precursors [1]. It is the most widely used Immunohistochemistry (IHC) marker to differentiate hematopoietic malignancies from non-hematopoietic tumors (small round blue cell tumors). 1. **Why Lymphoma is Correct:** Lymphomas are malignancies of lymphoid lineage. Since CD45 is expressed on all leukocytes (B-cells, T-cells, NK-cells, and granulocytes), it serves as a **pan-leukocyte marker**. Almost all Non-Hodgkin Lymphomas (NHL) are CD45 positive, making it the primary marker for confirming a lymphoid origin in undifferentiated tumors. 2. **Why Other Options are Incorrect:** * **Ewing Sarcoma:** This is a neuroectodermal tumor characterized by the **CD99 (MIC2)** marker. It is CD45 negative. * **Rhabdomyosarcoma:** A skeletal muscle tumor identified by markers like **Desmin, Myogenin, and MyoD1**. It is CD45 negative. * **Osteosarcoma:** A bone-forming tumor that expresses markers like **SATB2** and Osteonectin. It is CD45 negative. **High-Yield Clinical Pearls for NEET-PG:** * **CD45 Exceptions:** While most lymphomas are CD45+, **Classic Hodgkin Lymphoma (RS cells)** is characteristically **CD45 negative** (but CD15+ and CD30+). * **Small Round Blue Cell Tumors (SRBCT):** In a pediatric patient with an undifferentiated SRBCT, the first step in IHC is usually CD45. If positive, it suggests Lymphoma; if negative, other markers like CD99 (Ewing’s) or Desmin (RMS) are evaluated. * **Lineage Specificity:** CD45 confirms the cell is a leukocyte, but further markers (CD3 for T-cells, CD20 for B-cells) are needed to sub-classify the lymphoma [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. 596-598.

Question 1

A 63-year-old man presents with splenomegaly and lymphadenopathy. Immunophenotype was positive for CD19, CD79b, and FMC7. What is the most likely diagnosis?

Accepted Answer

Mantle cell lymphoma (MCL)

Answer

Hairy cell leukemia

Answer

Chronic lymphocytic leukemia (CLL)

Answer

Follicular lymphoma

Question 2

Auer rods are characteristic findings in which of the following conditions?

Accepted Answer

Acute myeloid leukemia, promyelocytic type

Answer

Myelodysplastic syndrome with excess blasts

Answer

Acute myeloid leukemia with myelodysplasia-related changes

Answer

Acute lymphoblastic leukemia

Question 3

Increased LAP score is seen in which of the following conditions?

Accepted Answer

Myelofibrosis

Answer

Chronic myeloid leukemia

Answer

Paroxysmal nocturnal hemoglobinuria

Answer

Megaloblastic anemia

Question 4

Schistocytes are found in which of the following conditions?

Accepted Answer

Both TTP and DIC

Answer

Thrombotic Thrombocytopenic Purpura (TTP)

Answer

Disseminated Intravascular Coagulation (DIC)

Answer

March hemoglobinuria

Question 5

Which subtype of Acute Myeloid Leukemia (AML) commonly causes gingival hypertrophy?

Accepted Answer

M4

Answer

M1

Answer

M2

Answer

M3

Question 6

Increased fetal hemoglobin (HbF) is seen in which of the following conditions?

Accepted Answer

Juvenile CML

Answer

Congenital red cell aplasia

Answer

Hereditary spherocytosis

Answer

AML

Question 7

Glanzmann thrombasthenia is due to a defect in which of the following?

Accepted Answer

Glycoprotein IIb/IIIa complex

Answer

Glycoprotein Ib-IX complex

Answer

CD68

Answer

Von Willebrand factor

Question 8

Hallmark cells are characteristic findings in which of the following hematological malignancies?

Accepted Answer

Anaplastic large-cell lymphoma

Answer

Diffuse large B-cell lymphoma

Answer

Hodgkin lymphoma

Answer

Hairy cell leukemia

Question 9

Marginal zone lymphoma is a type of:

Accepted Answer

B cell lymphoma

Answer

T cell lymphoma

Answer

NK cell lymphoma

Answer

Hodgkin lymphoma

Question 10

Leukocyte common antigen (CD45) is typically seen in which of the following malignancies?

Accepted Answer

Lymphoma

Answer

Ewing sarcoma

Answer

Rhabdomyosarcoma

Answer

Osteosarcoma

Hematopathology — MCQs

Hematopathology — MCQs

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