Sezary cells show which type of nucleus?
Which of the following is NOT seen in polycythemia vera?
Which of the following statements is true regarding the Duffy Fy(a-b-) blood group?
What is a distinguishing feature of reticulocytes?
Which antigen is tested in routine Rh typing?
The most common translocation seen in patients with Multiple Myeloma is:
What is the Thomsen Friedenreich phenomenon?
Which of the following statements about Polycythemia vera is false?
MALT lymphoma is positive for which of the following markers?
Which of the following statements about sickle cell anemia is false?
Explanation: ***Cerebriform*** - **Sezary cells** are characterized by their distinctive **cerebriform nuclei**, giving them an irregular, convoluted appearance [1,2]. - This finding is a hallmark of **cutaneous T-cell lymphoma** and emphasizes their potential malignancy [1,2]. *Round* - Round nuclei do not reflect the typical morphology of **Sezary cells**, which are noted for their **irregular shape**. - Other lymphocytes may exhibit round nuclei, but this does not specifically indicate a **Sezary cell** presence. *Pleomorphic* - While some malignant cells might show **pleomorphic nuclei**, Sezary cells uniquely showcase **cerebriform nuclei** rather than varying shapes [1,2]. - Pleomorphic is not a defining characteristic of **Sezary cells**, making this description inaccurate. *Eosinophillic* - Eosinophilic refers to cells that stain positively for **eosin**, typically associated with **eosinophils**, which is not relevant to **Sezary cells**. - Sezary cells are more about their **nuclear morphology** and less about eosinophilic staining characteristics. **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. 564-565. [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. 613-614.
Explanation: ***Increased erythropoietin*** - In polycythemia vera, patients usually exhibit **low erythropoietin levels** due to feedback inhibition from increased red blood cell mass. - The condition is driven by a **myeloproliferative disorder** [2], not by increased erythropoietin stimulation. *Most common cause of polycythemia* - This option is incorrect because polycythemia vera is specifically a type of **primary polycythemia** [1], rather than the most common cause, which is often **secondary causes** such as hypoxia or abnormal erythropoietin production. - Other causes including chronic lung disease or renal tumors are more prevalent sources of increased red blood cell production. *Intrinsic abnormality of hematopoietic precursors* - While polycythemia vera indeed involves an **abnormality in hematopoietic stem cells** [1], it is not the only mechanism leading to polycythemia; many cases have secondary causes. - Hence, this option misrepresents the specific and more accurate characterization of polycythemia vera. *Erythropoietin independent growth of red cell progenitors* - Polycythemia vera is associated with **erythropoietin-independent** proliferation of hematopoietic cells [2], which is characteristic of the condition due to mutations in **JAK2** [2,3]. - This accurately reflects a significant feature of the disease, aligning closely with the pathophysiology. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Red Blood Cell and Bleeding Disorders, pp. 663-664. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 614-615. [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. 626-627.
Explanation: ***lacks Fy(b) antigen*** - The **Duffy Fy(a-b-)** phenotype indicates absence of both Fy<sup>a</sup> and Fy<sup>b</sup> antigens on red blood cells. - Since the phenotype is **Fy(a-b-)**, it definitively lacks the **Fy<sup>b</sup> antigen** (indicated by the "b-" notation). - This phenotype is common in people of **African descent** and confers natural **resistance to Plasmodium vivax malaria**, as these antigens serve as receptors for the parasite to enter RBCs. *lacks H- antigen* - The **H antigen** belongs to the **H/h blood group system** and is a precursor to A and B antigens in the ABO system. - The absence of H antigen (Bombay phenotype - Oh) is completely **unrelated to the Duffy blood group system**. - Duffy antigens are on the **DARC (Duffy Antigen Receptor for Chemokines)** protein, distinct from the H antigen. *lacks A-antigen* - The **A antigen** is part of the **ABO blood group system** and defines blood types A and AB. - The Duffy blood group system is **genetically and structurally independent** from the ABO system. - Having Fy(a-b-) phenotype does not affect A antigen expression. *All of the options* - This is incorrect because the Duffy Fy(a-b-) phenotype **specifically refers only to the absence of Duffy antigens** (Fy<sup>a</sup> and Fy<sup>b</sup>). - It has **no relationship** with A, B, or H antigens, which belong to different blood group systems controlled by different genes on different chromosomes.
Explanation: ***Presence of residual RNA and ribosomes*** - This is the **defining and most distinguishing feature** of reticulocytes that differentiates them from mature red blood cells. - Reticulocytes contain residual **ribosomal RNA** and other organelles that are lost when they mature into erythrocytes. - This residual RNA forms a **reticular (network-like) pattern** when stained with supravital stains like **new methylene blue** or **brilliant cresyl blue**, which is the basis for their name and identification. - The presence of RNA allows for **reticulocyte counting**, an important marker of bone marrow erythropoietic activity. *Slightly larger in size than RBCs* - While reticulocytes may be slightly larger (polychromatophilic appearance), size variation is **not specific** and overlaps significantly with mature RBCs. - Size is not a reliable distinguishing feature and is not used for identification or counting. *Mature in bone marrow* - Reticulocytes are **released from the bone marrow** as immature red cells and complete their maturation in the **peripheral circulation** over 24-48 hours. - They do not fully mature in the bone marrow; their presence in peripheral blood is normal. *Constitute approximately 1% of the red cells* - Normal reticulocyte count is **0.5-2%** (or approximately 1%) of total red blood cells in healthy adults. - This is a **population characteristic** indicating normal erythropoietic activity, not a distinguishing cellular feature.
Explanation: ***D antigen*** - Routine Rh typing specifically tests for the **D antigen**, which determines the Rh status of an individual as Rh-positive or Rh-negative [1]. - The presence of the **D antigen** is crucial for blood transfusions and pregnancy management [1]. *A antigen* - The **A antigen** is tested in the context of the ABO blood group system, not specifically for Rh typing. - It does not provide information regarding the Rh factor which is critical in blood compatibility. *C antigen* - Similar to the **A antigen**, the **C antigen** is part of the broader Rh system but is not routinely assessed in standard Rh typing. - Its testing is typically reserved for specific clinical scenarios involving Rh incompatibility. *B antigen* - The **B antigen** pertains to the ABO blood group and does not relate to the Rh factor or routine Rh typing. - Rh typing is solely focused on the **presence of the D antigen** to determine the Rh status. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 627-628.
Explanation: ***t(11;14)*** - This translocation is the **most common cytogenetic abnormality** found in patients with multiple myeloma, occurring in approximately 15-20% of cases. - It results in the juxtaposition of the **IgH gene on chromosome 14** with the **cyclin D1 gene on chromosome 11**, leading to overexpression of cyclin D1. *t(4;14)* - This translocation, occurring in about 5-10% of patients, is associated with a **poor prognosis** in multiple myeloma. - It involves the IgH gene on chromosome 14 and the **FGFR3 and MMSET genes on chromosome 4**, leading to their upregulation. *t(14;16)* - This translocation is also associated with a **poor prognosis** and is less common than t(11;14) or t(4;14), found in about 2-5% of cases. - It involves the **IgH gene on chromosome 14** and the **c-MAF gene on chromosome 16**, leading to overexpression of c-MAF. *t(14;20)* - This translocation is **rarely observed** in multiple myeloma patients, typically occurring in less than 1% of cases. - It involves the **IgH gene on chromosome 14** and the **MAFB gene on chromosome 20**, which can also contribute to disease progression.
Explanation: ***Exposure of cryptic T-antigen on red blood cells*** - The Thomsen Friedenreich phenomenon, also known as **T-activation**, occurs when bacterial enzymes (neuraminidase) remove N-acetylneuraminic acid (sialic acid) residues from red cell surface glycoproteins, **unmasking the cryptic T-antigen** (Thomsen-Friedenreich antigen). - This unmasking leads to the red blood cells becoming agglutinable by naturally occurring **anti-T antibodies** present in almost all adult human sera, resulting in polyagglutination. - The T-antigen is not newly synthesized but is **pre-existing and cryptic**, hidden beneath sialic acid residues until exposed by bacterial neuraminidase activity. *Agglutination of red blood cells by anti-T antibodies* - While agglutination by anti-T antibodies is a *consequence* of the Thomsen Friedenreich phenomenon, it is not the phenomenon itself. The phenomenon describes the underlying cellular change - the **exposure of the cryptic T-antigen**. - This polyagglutination occurs because anti-T antibodies are naturally present in nearly all adult human sera. *Agglutination of red blood cells by all blood group sera* - The Thomsen Friedenreich phenomenon specifically involves agglutination by **anti-T antibodies**, which are naturally occurring and widely present, but it does not mean agglutination by *all* blood group sera (e.g., anti-A, anti-B, anti-D won't cause agglutination based on T-activation alone). - The T-antigen is distinct from the **ABO blood group antigens** and other blood group systems. *Association with certain malignancies* - While T-antigen (Tn antigen) can be expressed on certain **malignant cells** (tumor-associated antigen) and is relevant in cancer immunology, this is a separate clinical context from the Thomsen Friedenreich phenomenon in **blood banking** and transfusion medicine. - The Thomsen Friedenreich phenomenon primarily refers to the **acquired exposure** of cryptic T-antigen on red blood cells due to bacterial neuraminidase action, typically seen in infections or bacterial contamination.
Explanation: ***Decrease LAP score*** - In polycythemia vera, the **LAP (leukocyte alkaline phosphatase) score** is typically increased, indicating more mature leukocytes. - A **decrease in LAP score** is not consistent with the disease, making this statement incorrect. *Increased platelets* - Polycythemia vera often results in **thrombocytosis**, characterized by increased platelet counts [1]. - This is a common feature of the disorder, reflecting overproduction of blood cells in the bone marrow. *Leucocytosis* - Patients with polycythemia vera frequently exhibit **leucocytosis**, or increased white blood cell counts, due to hypercellularity of the bone marrow [1]. - This is an important aspect of the disease, often seen alongside increases in red blood cells and platelets. *Increased vit B12* - An elevation in **vitamin B12** levels can occur in polycythemia vera, often due to increased binding proteins. - This is a well-recognized phenomenon associated with the increased cell turnover in this condition. **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. 626-627.
Explanation: ***CD20*** - MALT lymphoma is a type of **B-cell non-Hodgkin lymphoma**, and CD20 is a **pan B-cell marker consistently expressed** in MALT lymphomas. - CD20 positivity is **crucial for diagnosis** and is the **primary therapeutic target** for anti-CD20 monoclonal antibody therapy (Rituximab). - In diagnostic practice, **CD20 is the most important B-cell marker** for identifying MALT lymphoma and guiding treatment decisions. *CD19* - CD19 is also a **pan B-cell marker** and is **typically positive in MALT lymphoma** along with CD20. - However, in the context of this question, **CD20 is the preferred answer** because it is the **standard diagnostic marker emphasized in clinical practice** and the **primary therapeutic target**. - Both markers are positive, but CD20 has greater **clinical and therapeutic significance** in MALT lymphoma management. *CD43* - CD43 is primarily a **T-cell and myeloid marker**, but can show **aberrant expression in 40-50% of MALT lymphomas**. - While it may be positive in some cases, it is **not a defining B-cell lineage marker** and is not used as a primary diagnostic criterion for MALT lymphoma. - Its variable expression makes it **less reliable** than consistent B-cell markers like CD20. *CD5* - CD5 is typically associated with **T-cells** and certain B-cell lymphomas, particularly **chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL)** and **mantle cell lymphoma**. - **MALT lymphoma is characteristically CD5-negative**, which is an important feature for **differentiating it from CD5+ B-cell lymphomas**.
Explanation: ***Ringed sideroblast*** - **Ringed sideroblasts** are not typically associated with sickle cell anemia; they are indicative of disorders like **sideroblastic anemia**. - In sickle cell anemia, the primary findings include **hemolysis** and ineffective erythropoiesis, not ringed sideroblasts [3]. *Howell jolly bodies* - These bodies are remnants of nuclear material and can be found in individuals with **spleen dysfunction**, which can occur in sickle cell anemia [1]. - They are actually a common finding due to **hyposplenism** or **asplenia** in patients with sickle cell disease [2]. *Sickle cells* - The presence of **sickle-shaped red blood cells** is a hallmark of sickle cell anemia, caused by the mutation in the **beta-globin chain** [3]. - These sickle cells are responsible for the characteristic complications of the disease, such as **vaso-occlusive crises** [1][3]. *Target cells* - Target cells, or **codocytes**, are often seen in disorders like **thalassemia** and liver disease, and can also be present in sickle cell anemia. - They are formed due to an increase in the **surface area to volume ratio** of red blood cells, often secondary to **membrane abnormalities** seen in sickle cell changes [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. 644-646. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Diseases Of The Urinary And Male Genital Tracts, pp. 570-571. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 598-599.
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