Hematopathology Practice Questions

Q: Which CD marker is expressed by human stem cells?

CD34. **Explanation:** **CD34** is the hallmark surface marker for **Hematopoietic Stem Cells (HSCs)** and progenitor cells [1]. It is a transmembrane phosphoglycoprotein that mediates cell adhesion to the bone marrow extracellular matrix. As these stem cells differentiate into mature lineages, the expression of CD34 is lost; therefore, it is used clinically to identify, quantify, and isolate stem cells for peripheral blood stem cell transplantation [2]. **Analysis of Incorrect Options:** * **CD14:** This is a specific marker for the **monocyte/macrophage** lineage. It acts as a co-receptor for bacterial lipopolysaccharide (LPS). * **CD8:** This is a marker for **Cytotoxic T-cells** and a subset of Natural Killer (NK) cells. It interacts with MHC Class I molecules. * **CD10:** Also known as **CALLA** (Common Acute Lymphoblastic Leukemia Antigen), it is expressed on pre-B cells and germinal center B-cells. It is a key diagnostic marker for Childhood B-ALL and Follicular Lymphoma. **High-Yield Clinical Pearls for NEET-PG:** * **Stem Cell Harvest:** In clinical practice, a minimum dose of **$2 \times 10^6$ CD34+ cells/kg** is required for successful engraftment in a transplant recipient. * **Flow Cytometry:** CD34 is essential for diagnosing **Acute Myeloid Leukemia (AML)**, as it helps distinguish blasts from mature cells. * **Other Stem Cell Markers:** While CD34 is the most common, **CD133** is another marker used to identify primitive hematopoietic and neural stem cells. * **Negative Markers:** True HSCs are typically **CD34+** but **Lin-** (lineage negative) and **CD38-**. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Heart, pp. 588-589. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 584-586.

Q: Non-specific esterase is present in which of the following conditions?

Acute Myeloid Leukemia (AML). **Explanation:** The correct answer is **Acute Myeloid Leukemia (AML)**, specifically the monocytic subtypes (AML-M4 and M5) [1]. **1. Why the Correct Answer is Right:** Non-specific esterase (NSE), such as alpha-naphthyl acetate esterase, is a cytochemical stain used to identify cells of **monocytic lineage** [1]. In the FAB classification of AML, **AML-M4 (Acute Myelomonocytic Leukemia)** and **AML-M5 (Acute Monocytic Leukemia)** show strong positivity for NSE [1]. The enzyme helps differentiate these monocytic blasts from myeloblasts (which are typically NSE negative but Myeloperoxidase positive). A key diagnostic feature is that NSE activity in monocytes is **inhibited by Sodium Fluoride (NaF)**. **2. Why Incorrect Options are Wrong:** * **Megakaryocytic leukemia (AML-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 characteristically NSE negative. They are typically identified by Periodic Acid-Schiff (PAS) positivity in a "block-like" pattern and TdT expression. * **Erythroleukemia (AML-M6):** Erythroblasts are generally NSE negative but show strong, globular PAS positivity. **3. High-Yield Clinical Pearls for NEET-PG:** * **MPO (Myeloperoxidase):** Most sensitive stain for myeloid differentiation (Positive in M1, M2, M3, M4). * **Sudan Black B (SBB):** Stains phospholipids; mimics MPO but can be used on older smears. * **NSE (Non-specific Esterase):** Marker for **Monocytes** (M4, M5) [1]. * **Specific Esterase (Chloroacetate Esterase):** Marker for **Granulocytes** (Neutrophils). * **PAS (Periodic Acid-Schiff):** Positive in ALL (block-like) and AML-M6 (diffuse/globular). **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.

Question 1

Which of the following is NOT true of Hodgkin's lymphoma?

Accepted Answer

Osteolytic metastasis

Answer

Bimodal age pattern

Answer

Less common in females

Answer

Contiguous spread

Question 2

Which CD marker is expressed by human stem cells?

Accepted Answer

CD34

Answer

CD14

Answer

CD8

Answer

CD10

Question 3

Neoplastic cells in Franklin disease express which of the following markers?

Accepted Answer

CD79a

Answer

CD5

Answer

CD10

Answer

CD55

Question 4

Paroxysmal nocturnal hemoglobinuria is due to what type of defect?

Accepted Answer

Acquired red cell defect

Answer

Congenital red cell defect

Answer

Autoimmune defect

Answer

Lead poisoning

Question 5

In alloimmune thrombocytopenia, against which Human Platelet Antigen (HPA) is the antibody typically found?

Accepted Answer

HPA 1a

Answer

HPA 1b

Answer

HPA 2a

Answer

HPA 2b

Question 6

What is the most common cause of myelophthisic anemia?

Accepted Answer

Multiple metastatic secondaries

Answer

Multiple myeloma

Answer

Non-Hodgkin lymphoma (NHL)

Answer

Leukemia

Question 7

Non-specific esterase is present in which of the following conditions?

Accepted Answer

Acute Myeloid Leukemia (AML)

Answer

Megakaryocytic leukemia

Answer

Lymphocytic leukemia

Answer

Erythroleukemia

Question 8

Fibrin degradation products help in the detection of which condition?

Accepted Answer

Disseminated Intravascular Coagulation (DIC)

Answer

Hemophilia

Answer

Thrombocytopenic purpura

Answer

Thrombasthenia

Question 9

Flame cells are seen in which condition?

Accepted Answer

Multiple myeloma

Answer

Malignant melanoma

Answer

Nodular colloid goiter

Answer

Hashimoto thyroiditis

Question 10

A 55-year-old man newly diagnosed with leukemia undergoes genetic studies that reveal a t(9;22) translocation (the Philadelphia chromosome). Which of the following would a complete blood count most likely show?

Accepted Answer

Increased neutrophil count

Answer

Increased lymphocyte count

Answer

Numerous lymphoblasts

Answer

Numerous myeloblasts

Hematopathology — MCQs

Hematopathology — MCQs

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