Histology of blood and hematopoiesis US Medical PG Practice Questions and MCQs
Practice US Medical PG questions for Histology of blood and hematopoiesis. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Histology of blood and hematopoiesis US Medical PG Question 1: A 66-year-old man comes to the physician for a 3-month history of fatigue. He has hypertension and hyperlipidemia. He had a transient ischemic attack 3 years ago. He drinks 3 beers a day, and sometimes a couple more on social occasions. He currently takes aspirin, simvastatin, hydrochlorothiazide, and metoprolol. His temperature is 37.1°C (98.8°F), pulse is 78, respirations are 19/min, and oxygen saturation on room air is 97%. He is in no distress but shows marked pallor and has multiple pinpoint, red, nonblanching spots on his extremities. On palpation, his spleen is significantly enlarged. Laboratory studies show a hemoglobin of 8.0 g/dL, a leukocyte count of 80,000/mm3, and a platelet count of 34,000/mm3. A blood smear shows immature cells with large, prominent nucleoli and pink, elongated, needle-shaped cytoplasmic inclusions. Which of the following is the most likely diagnosis?
- A. Cirrhosis
- B. Acute lymphoblastic leukemia
- C. Chronic lymphocytic leukemia
- D. Myelodysplastic syndrome
- E. Acute myelogenous leukemia (Correct Answer)
Histology of blood and hematopoiesis Explanation: **Acute myelogenous leukemia**
- The presence of **fatigue**, **marked pallor**, **splenomegaly**, **petechiae** (pinpoint, red, nonblanching spots), and **pancytopenia** (anemia, leukocytosis with immature forms, thrombocytopenia) are highly suggestive of acute leukemia.
- The blood smear findings of **immature cells with large, prominent nucleoli** and **pink, elongated, needle-shaped cytoplasmic inclusions** (likely **Auer rods**) are pathognomonic for **acute myelogenous leukemia (AML)**.
*Cirrhosis*
- While **splenomegaly** and **pancytopenia** can occur in cirrhosis due to portal hypertension and hypersplenism, the specific blood smear findings of **immature cells** and **Auer rods** are not characteristic of cirrhosis.
- The patient's alcohol intake could contribute to cirrhosis, but the hematological picture points definitively away from liver disease as the primary diagnosis.
*Acute lymphoblastic leukemia*
- Although acute lymphoblastic leukemia (ALL) presents with **fatigue**, **pallor**, and **pancytopenia**, the **immature cells** in ALL are lymphoblasts, which **lack Auer rods**.
- The specific morphology described (large, prominent nucleoli, needle-shaped cytoplasmic inclusions) is inconsistent with ALL.
*Chronic lymphocytic leukemia*
- CLL typically presents with **lymphocytosis** (extremely high leukocyte count composed of mature-appearing lymphocytes) and often **splenomegaly**, but usually **without significant anemia or thrombocytopenia** at presentation.
- The presence of **immature cells** and **Auer rods** is inconsistent with CLL, which involves mature B-lymphocytes.
*Myelodysplastic syndrome*
- MDS can cause **cytopenias** and may involve **immature blast forms**, but the blast count is typically less than 20% in the bone marrow (or periphery) and it does **not typically present with Auer rods** in circulating blasts.
- The profound leukocytosis with highly immature cells and specific inclusions points beyond MDS to an acute leukemia.
Histology of blood and hematopoiesis US Medical PG Question 2: During the third week of development, the blastocyst undergoes a variety of differentiation processes responsible for the formation of the gastrula and, eventually, the embryo. This differentiation creates cell lineages that eventually become a variety of body systems. What cell lineage, present at this date, is responsible for the formation of the liver?
- A. Neuroectoderm
- B. Syncytiotrophoblasts
- C. Ectoderm
- D. Endoderm (Correct Answer)
- E. Mesoderm
Histology of blood and hematopoiesis Explanation: ***Endoderm***
- The **endoderm** is one of the three primary germ layers that develops during gastrulation and is responsible for forming the lining of the **gastrointestinal tract** and associated organs, including the **liver** and pancreas.
- Liver development begins from an outgrowth of the **foregut endoderm**, which differentiates into hepatocytes and bile duct cells, forming the hepatic parenchyma.
*Neuroectoderm*
- **Neuroectoderm** is a specialized part of the ectoderm that gives rise to the entire **nervous system**, including the brain, spinal cord, and peripheral nerves.
- It does not contribute to the formation of visceral organs like the liver.
*Syncytiotrophoblasts*
- **Syncytiotrophoblasts** are a layer of the **trophoblast** that form part of the placenta, specifically involved in hormone production and nutrient exchange between the mother and fetus.
- They are part of the supporting structures for pregnancy and do not contribute to the embryonic germ layers or organ formation within the embryo itself.
*Ectoderm*
- The **ectoderm** is the outermost germ layer and gives rise to the **epidermis of the skin**, hair, nails, nervous system, and sensory organs.
- While it forms the outer coverings and nervous system, it does not directly form internal organs like the liver.
*Mesoderm*
- The **mesoderm** is the middle germ layer, responsible for forming **muscle**, **bone**, connective tissue, the circulatory system, kidneys, and gonads.
- While mesoderm contributes supporting structures to the liver (blood vessels, connective tissue, hematopoietic cells), the **hepatic parenchyma** (hepatocytes and bile ducts) is derived from the endoderm, making endoderm the primary cell lineage responsible for liver formation.
Histology of blood and hematopoiesis US Medical PG Question 3: An investigator is studying the immune response and the spleen in a mouse model infected with Escherichia coli. Which of the following anatomical sites in the spleen is important for the secondary maturation and affinity maturation of B cells that will ultimately target Escherichia coli?
- A. Sinusoids
- B. Periarteriolar lymphatic sheaths
- C. Marginal zone
- D. Red pulp
- E. Germinal center (Correct Answer)
Histology of blood and hematopoiesis Explanation: ***Germinal center***
- The **germinal centers** are the primary sites within secondary lymphoid organs, including the spleen, where B cells undergo **proliferation**, **somatic hypermutation**, and **affinity maturation** following antigen exposure.
- This process is crucial for generating high-affinity antibodies capable of effectively targeting pathogens like *Escherichia coli*.
*Sinusoids*
- **Sinusoids** are specialized vascular channels found throughout the spleen, particularly in the red pulp, responsible for filtering blood and removing old or damaged red blood cells.
- They are not directly involved in the secondary maturation or affinity maturation of B cells.
*Periarteriolar lymphatic sheaths*
- The **periarteriolar lymphatic sheaths (PALS)** are T-cell rich areas in the white pulp of the spleen, surrounding central arterioles.
- While important for T-cell activation, the main site for B-cell affinity maturation is the germinal center, which forms within B cell follicles adjacent to the PALS.
*Marginal zone*
- The **marginal zone** is a specialized area at the periphery of the white pulp, rich in unique B cell populations that respond rapidly to T-cell independent antigens.
- While it plays a role in initial immune responses, it is not the primary site for the secondary maturation and affinity maturation of B cells.
*Red pulp*
- The **red pulp** makes up the majority of the spleen and is primarily involved in filtering blood, removing old red blood cells, and storing platelets.
- While it contains macrophages and other immune cells, it is not the main site for B-cell secondary maturation and affinity maturation, which occurs in the white pulp's germinal centers.
Histology of blood and hematopoiesis US Medical PG Question 4: A 12-year-old boy presents to the emergency department with a recent history of easy bleeding. He experienced multiple episodes of epistaxis and bleeding gums over the past two days. He also had flu-like symptoms a week ago which resolved over the past few days. His past medical history is notable for well-controlled asthma. His temperature is 98.9°F (37°C). Physical examination is notable for a petechial rash. No splenomegaly is noted. A coagulation panel reveals an elevation in bleeding time with normal PT and PTT. The blood component that is most likely deficient in this patient contains granules of which of the following?
- A. Myeloperoxidase
- B. Heparin
- C. Tryptase
- D. Major basic protein
- E. von Willebrand factor (Correct Answer)
Histology of blood and hematopoiesis Explanation: ***von Willebrand factor***
- This patient's presentation with **easy bleeding** (epistaxis, bleeding gums), **petechial rash**, and a history of a recent **viral infection** followed by normal PT/PTT but **elevated bleeding time** is highly suggestive of **Immune Thrombocytopenic Purpura (ITP)**.
- In ITP, antibodies attack **platelets**, leading to their destruction and a deficiency. Platelet alpha-granules contain **von Willebrand factor**, platelet factor 4, and fibrinogen, which are crucial for hemostasis.
*Myeloperoxidase*
- **Myeloperoxidase** is found in the **azurophilic granules** of neutrophils and monocytes, not platelets, and is involved in microbial killing.
- A deficiency in myeloperoxidase would primarily impair immune function rather than cause a bleeding disorder with elevated bleeding time.
*Heparin*
- **Heparin** is an anticoagulant found primarily in the granules of **mast cells** and basophils, which are involved in allergic reactions and inflammation.
- Heparin is not a component of platelet granules, and its deficiency would lead to increased clotting, not bleeding.
*Tryptase*
- **Tryptase** is an enzyme found in the granules of **mast cells**, released during allergic reactions and anaphylaxis.
- It is not associated with platelet function or the type of bleeding disorder described here.
*Major basic protein*
- **Major basic protein (MBP)** is a cytotoxic protein found in the granules of **eosinophils**, primarily involved in defense against parasitic infections.
- Its presence or absence is unrelated to platelet function or this patient's bleeding symptoms.
Histology of blood and hematopoiesis US Medical PG Question 5: A 7-year-old girl presents to a new pediatrician with fever, shortness of breath, and productive cough. She had similar symptoms a few weeks ago. The girl was born at 39 weeks gestation via spontaneous vaginal delivery. She is up to date on all vaccines and is meeting all developmental milestones. A further review of her history reveals seizures, upper respiratory infections, and cellulitis. On physical examination, the patient is pale with white-blonde hair and pale blue eyes. Which of the following would you expect to see on a peripheral blood smear for this patient?
- A. Polymorphonuclear leukocytes containing giant inclusion bodies (Correct Answer)
- B. Predominance of band leukocytes
- C. Downey cells
- D. Stippled eosinophils
- E. Significant basophil predominance
Histology of blood and hematopoiesis Explanation: ***Polymorphonuclear leukocytes containing giant inclusion bodies***
- This constellation of symptoms: **recurrent infections** (respiratory infections, cellulitis), **neurological abnormalities** (seizures), and **partial albinism** (pale skin, white-blonde hair, pale blue eyes) is characteristic of **Chédiak-Higashi syndrome**.
- **Chédiak-Higashi syndrome** is an autosomal recessive disorder characterized by defective lysosomal trafficking, leading to the formation of abnormally large **lysosomes** and **granules** in various cell types, including melanocytes, lymphocytes, and granulocytes. These giant granules are visible as **inclusion bodies** within polymorphonuclear leukocytes on a peripheral blood smear.
*Predominance of band leukocytes*
- A predominance of **band leukocytes** (immature neutrophils) indicates a **left shift**, which is commonly seen in acute bacterial infections and suggests the bone marrow is rapidly producing neutrophils.
- While this patient has infections, a left shift is a general response to infection and not a specific finding for Chédiak-Higashi syndrome, which primarily involves abnormal inclusion bodies.
*Downey cells*
- **Downey cells** are atypical lymphocytes, specifically activated cytotoxic T cells, classically associated with **infectious mononucleosis** caused by the Epstein-Barr virus (EBV).
- This patient's chronic and recurrent bacterial infections and characteristic albinism do not suggest infectious mononucleosis.
*Stippled eosinophils*
- **Stippled eosinophils** (basophilic stippling within eosinophils) are not a recognized abnormality or an indicator of any specific disease.
- While eosinophilia can occur in certain conditions (e.g., parasitic infections, allergic reactions), the presence of "stippled" eosinophils is not a known hematologic feature.
*Significant basophil predominance*
- A significant basophil predominance, or **basophilia**, can be seen in conditions like **myeloproliferative neoplasms** (e.g., chronic myeloid leukemia) or certain allergic reactions.
- This finding is not consistent with the clinical presentation of recurrent infections, neurological issues, and albinism seen in this patient.
Histology of blood and hematopoiesis US Medical PG Question 6: A 72-year-old woman comes to the physician because of a 1-month history of progressive fatigue and shortness of breath. Physical examination shows generalized pallor. Laboratory studies show:
Hemoglobin 5.8 g/dL
Hematocrit 17%
Mean corpuscular volume 86 μm3
Leukocyte count 6,200/mm3 with a normal differential
Platelet count 240,000/mm3
A bone marrow aspirate shows an absence of erythroid precursor cells. This patient’s condition is most likely associated with which of the following?
- A. Cold agglutinins
- B. Thymic tumor (Correct Answer)
- C. HbF persistence
- D. Parvovirus B19 infection
- E. Lead poisoning
Histology of blood and hematopoiesis Explanation: ***Thymic tumor***
- The patient's **normocytic anemia** (Hb 5.8 g/dL, Hct 17%, MCV 86 μm3) and the **absence of erythroid precursor cells** in the bone marrow aspirate are characteristic findings of **pure red cell aplasia (PRCA)**.
- **Pure red cell aplasia (PRCA)** in adults is frequently associated with an underlying **thymoma**, with up to 50% of adult PRCA cases linked to this condition.
*Cold agglutinins*
- Cold agglutinins are characteristic of **cold agglutinin disease**, an **autoimmune hemolytic anemia**.
- This condition typically presents with signs of **hemolysis** (e.g., elevated reticulocytes, bilirubin, LDH) and would not show an **absence of erythroid precursor cells** in the bone marrow.
*HbF persistence*
- **Hereditary persistence of fetal hemoglobin (HPFH)** is a benign condition where **HbF** production continues into adulthood.
- It is not associated with anemia or bone marrow aplasia and usually results in normal hematological parameters, except for elevated HbF.
*Parvovirus B19 infection*
- **Parvovirus B19** can cause transient **aplastic crisis** by infecting and destroying erythroid precursors.
- While it causes PRCA-like features, it is typically an acute self-limiting condition, particularly in immunocompetent individuals, and is less likely to be an ongoing chronic cause in a 72-year-old without other risk factors for chronic infection or immunodeficiency.
*Lead poisoning*
- **Lead poisoning** typically causes a **microcytic hypochromic anemia** with **basophilic stippling** on peripheral blood smear.
- It primarily interferes with **heme synthesis** and would not cause a complete absence of erythroid precursor cells in the bone marrow.
Histology of blood and hematopoiesis US Medical PG Question 7: A 34-year-old man comes to the physician because of blurry vision and fatigue for 2 months. During this period, he has also had occasional bleeding from his gums after brushing his teeth. One month ago, he was diagnosed with deep vein thrombosis after returning from an overseas business meeting. His pulse is 118/min, respirations are 19/min, and blood pressure is 149/91 mm Hg. Pulse oximetry on room air shows an oxygen saturation of 97%. Examination shows bluish discoloration of the lips. The tip of the spleen is palpable 1 cm below the left costal margin. Sensory examination of the hands shows paresthesia. Hemoglobin concentration is 18 g/dL, hematocrit is 65%, leukocytes are 15,000/μL, and platelets are 470,000/μL. His serum erythropoietin concentration is decreased. Activation of which of the following is the most likely underlying cause of this patient's condition?
- A. Serine/threonine kinase
- B. Antiapoptotic molecule
- C. Nonreceptor tyrosine kinase (Correct Answer)
- D. Transcription factor
- E. Cytokine receptor
Histology of blood and hematopoiesis Explanation: ***Nonreceptor tyrosine kinase***
- This patient's symptoms (blurry vision, fatigue, gum bleeding, deep vein thrombosis, splenomegaly, **elevated hemoglobin, hematocrit, leukocytes, and platelets**, and **decreased erythropoietin**) are highly suggestive of **polycythemia vera**.
- Polycythemia vera is a myeloproliferative neoplasm characterized by a mutation in the **JAK2 gene**, which encodes a **nonreceptor tyrosine kinase**. This mutation leads to constitutive activation of the JAK-STAT pathway, resulting in uncontrolled proliferation of myeloid cells independent of growth factors.
*Serine/threonine kinase*
- While serine/threonine kinases are involved in various cellular signaling pathways, their constitutive activation is not the primary underlying cause of polycythemia vera.
- Mutations in serine/threonine kinases are more commonly associated with other conditions, such as certain cancers, but not specifically with the **JAK2 V617F mutation** characteristic of PV.
*Antiapoptotic molecule*
- Activation of antiapoptotic molecules plays a role in the survival of cancer cells, but it is a downstream effect rather than the primary initiating event in polycythemia vera.
- The **JAK2 mutation** leads to increased cell proliferation and reduced apoptosis indirectly by enhancing survival signals.
*Transcription factor*
- Transcription factors regulate gene expression, and their dysregulation can contribute to various diseases, including cancers. However, the direct activation of a transcription factor is not the root cause of polycythemia vera.
- The **JAK-STAT pathway** ultimately affects transcription factors, but the initial genetic defect is in the JAK2 kinase.
*Cytokine receptor*
- Cytokine receptors bind cytokines and initiate signaling cascades, often involving JAK kinases. While cytokine receptor signaling is hyperactive in polycythemia vera, the primary defect is not in the receptor itself but in the downstream **JAK2 kinase**.
- The **JAK2 V617F mutation** causes **cytokine-independent activation** of the signaling pathway, meaning the cells don't need external cytokines to proliferate.
Histology of blood and hematopoiesis US Medical PG Question 8: A 30-year-old man is admitted to the hospital with a presumed pneumonia and started on antibiotics. Two days later, the patient shows no improvement. Blood cultures reveal yeast with pseudophyphae. Which of the following cell types is most likely deficient or dysfunctional in this patient?
- A. Eosinophils
- B. Macrophages
- C. Neutrophils (Correct Answer)
- D. T-cells
- E. B-cells
Histology of blood and hematopoiesis Explanation: ***Neutrophils***
- The presence of **yeast with pseudohyphae** in blood cultures, particularly *Candida*, indicates a fungal infection.
- **Neutrophils** are crucial for the host defense against *Candida* and other fungal pathogens, so their deficiency or dysfunction would predispose to candidemia.
- Neutropenia or neutrophil dysfunction (e.g., chronic granulomatous disease) significantly increases risk of invasive candidiasis.
*Eosinophils*
- **Eosinophils** are primarily involved in defense against **parasitic infections** and in allergic reactions.
- They play a minimal role in the immune response to systemic fungal infections like candidemia.
*Macrophages*
- **Macrophages** are phagocytic cells that contribute to antifungal immunity, particularly in tissue surveillance and chronic infection control.
- However, **neutrophils** are the primary and most critical defense against acute *Candida* bloodstream infections.
- Macrophage deficiency alone does not typically predispose to candidemia as severely as neutrophil deficiency.
*T-cells*
- **T-cells** are important for cell-mediated immunity, particularly against **intracellular pathogens** and viral infections.
- While they play a role in modulating antifungal responses, their deficiency typically leads to infections with *Pneumocystis jirovecii* or severe mucocutaneous candidiasis, rather than disseminated candidemia.
*B-cells*
- **B-cells** are responsible for **humoral immunity** through antibody production, which is primarily effective against extracellular bacteria and toxins.
- They are not the primary line of defense against fungal infections such as candidemia.
Histology of blood and hematopoiesis US Medical PG Question 9: An investigator is conducting a study to document the histological changes in the respiratory tree of a chronic smoker. He obtains multiple biopsy samples from the respiratory system of a previously healthy 28-year-old man. Histopathological examination of one sample shows simple cuboidal cells with a surrounding layer of smooth muscle. Chondrocytes and goblet cells are absent. This specimen was most likely obtained from which of the following parts of the respiratory system?
- A. Terminal bronchiole (Correct Answer)
- B. Alveolar sac
- C. Main stem bronchus
- D. Bronchiole
- E. Respiratory bronchiole
Histology of blood and hematopoiesis Explanation: ***Terminal bronchiole***
- Terminal bronchioles are lined by **simple cuboidal epithelium** and contain surrounding **smooth muscle** but lack cartilage (chondrocytes) and goblet cells, matching the histological description.
- They represent the most distal purely conducting airways before respiratory bronchioles, where gas exchange begins.
*Alveolar sac*
- Alveolar sacs are primarily composed of **Type I and Type II pneumocytes** for gas exchange, and would not have a prominent smooth muscle layer or cuboidal cells in this described pattern.
- They are the terminal structures of the respiratory tree where gas exchange occurs, defined by very thin walls lacking cartilage and goblet cells.
*Main stem bronchus*
- The main stem bronchi are characterized by **pseudostratified ciliated columnar epithelium** with abundant **goblet cells** and contain **hyaline cartilage** (chondrocytes) in their walls.
- The presence of goblet cells and cartilage (chondrocytes) makes this option inconsistent with the given histological findings.
*Bronchiole*
- Bronchioles are generally lined by **ciliated columnar to cuboidal epithelium** with scattered goblet cells in larger ones, and they possess smooth muscle but lack cartilage.
- While they share some features with terminal bronchioles, the presence of goblet cells (even if sparse) distinguishes bronchioles from terminal bronchioles.
*Respiratory bronchiole*
- Respiratory bronchioles are distinguished by their walls having occasional **alveoli**, indicating the beginning of gas exchange. Their epithelium is cuboidal.
- They would not be described as having a "surrounding layer of smooth muscle" in isolation as clearly as a terminal bronchiole, and the presence of alveoli would be a key distinguishing feature.
Histology of blood and hematopoiesis US Medical PG Question 10: A 38-year-old man comes to the physician because of a 6-month history of chest discomfort and progressive dyspnea. He cannot do daily chores without feeling out of breath. He was diagnosed in childhood with a milder X-linked dystrophinopathy that has caused progressive proximal muscle weakness and gait abnormalities over the years. Physical examination shows a waddling gait and weak patellar reflexes. Cardiovascular examination shows a holosystolic murmur, displaced point of maximal impulse, and bilateral pitting edema of the ankles. Laboratory studies show elevated levels of brain natriuretic peptide. Which of the following is the most likely underlying cause of this patient's muscle weakness?
- A. Increased number of CTG repeats in the DMPK gene
- B. Interruption of microtubule depolymerization through stabilization of GDP-tubulin
- C. Impaired connection of cytoskeletal actin filaments to membrane-bound dystroglycan (Correct Answer)
- D. Cell–mediated cytotoxicity against skeletal muscle antigens in the endomysium
- E. Defective lysine-hydroxylysine crosslinking of tropocollagen
Histology of blood and hematopoiesis Explanation: ***Impaired connection of cytoskeletal actin filaments to membrane-bound dystroglycan***
- The description of a **milder X-linked dystrophinopathy** with progressive muscle weakness and gait abnormalities, coupled with cardiac manifestations like a **holosystolic murmur** and elevated **BNP**, is characteristic of a **dystrophinopathy**, such as **Becker muscular dystrophy**.
- **Dystrophin** is a critical protein that links the **cytoskeletal actin filaments** to the **dystroglycan complex** at the sarcolemma, providing mechanical stability to muscle fibers. Impaired connection leads to muscle fragility and degeneration.
*Increased number of CTG repeats in the DMPK gene*
- This describes **myotonic dystrophy type 1**, which is an autosomal dominant condition, not X-linked.
- While it causes muscle weakness, it is also associated with **myotonia**, testicular atrophy, and cataracts, which are not mentioned.
*Interruption of microtubule depolymerization through stabilization of GDP-tubulin*
- This mechanism is associated with **chemotherapeutic agents** like taxanes (e.g., paclitaxel, docetaxel), which interfere with cell division.
- It does not explain a genetic, progressive muscle weakness disorder.
*Cell–mediated cytotoxicity against skeletal muscle antigens in the endomysium*
- This describes the pathophysiology of **polymyositis**, an **inflammatory myopathy**.
- Polymyositis is an autoimmune condition and does not typically present as an X-linked inherited disorder diagnosed in childhood.
*Defective lysine-hydroxylysine crosslinking of tropocollagen*
- This mechanism is characteristic of disorders affecting **collagen synthesis** and cross-linking, such as **Ehlers-Danlos syndrome**.
- These conditions primarily affect connective tissue, leading to joint hypermobility, skin hyperextensibility, and tissue fragility, not primarily progressive muscle weakness due to dystrophin deficiency.
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