Question 1

The abnormal red cell membrane in PNH is highly sensitive to:

Accepted Answer

The abnormal red cell membrane in PNH is highly sensitive to complement, leading to intravascular hemolysis. This is due to the absence of complement regulatory proteins, such as CD55 and CD59, on the surface of affected cells. This makes PNH patients susceptible to a wide range of symptoms, including hemolytic anemia, thrombosis, and renal failure. Alloantibodies, drug-induced antibodies, and IL-1 do not play a significant role in the pathology of PNH.

Question 2

One of the major complications of PNH is:

Accepted Answer

One of the major complications of PNH is venous thrombosis. This occurs because PNH is associated with an increased risk of blood clots, including deep vein thrombosis and pulmonary embolism. Venous thrombosis can be life-threatening and requires prompt medical treatment. Iron overload, splenomegaly, and hepatomegaly may occur in some cases of PNH, but they are not considered major complications of the disease.

Question 3

What would be considered a typical platelet count in a patient with PNH?

Accepted Answer

The answer of What would be considered a typical platelet...

Question 4

The defect in PNH affects which cell type?

Accepted Answer

PNH (Paroxysmal Nocturnal Hemoglobinuria) is a disease that affects all blood cells, including leukocytes, platelets, and erythrocytes, due to a defect in the PIGA gene, which is crucial for the synthesis of GPI anchors that attach proteins to the cell membrane.

Question 5

Most PNH patients present with a normocytic/normochromic anemia and:

Accepted Answer

PNH patients often present with normocytic/normochromic anemia along with periodic acute hemolytic episodes and cytopenia. Bone marrow hypoplasia may also be present in some cases.

Question 6

Slight macrocytosis or polychromasia may be seen in the peripheral blood of a PNH patient due to increased __________.

Accepted Answer

Slight macrocytosis or polychromasia may be seen in the peripheral blood of a PNH patient due to increased reticulocytes, as the bone marrow tries to compensate for the hemolysis by increasing red cell production.

Question 7

Which statement is true regarding a positive Ham's test result?

Accepted Answer

A positive Ham's test result indicates that hemolysis occurs with a patient's cells but not control cells. This suggests the presence of an antibody that is causing lysis of the patient's cells.

Question 8

The bone marrow in a PNH patient reveals:

Accepted Answer

PNH (paroxysmal nocturnal hemoglobinuria) is a rare acquired hematopoietic stem cell disorder. In PNH patients, bone marrow shows erythroid hyperplasia and megakaryocytic hyperplasia. Myeloid lineage may be normal or decreased. Hence, the correct choice is A.

Question 9

Which factors help to determine the presence of PNH?

Accepted Answer

Decrease in acetylcholinesterase is a factor that helps to determine the presence of Paroxysmal Nocturnal Hemoglobinuria (PNH), a rare, acquired, life-threatening disease of the blood characterized by the destruction of red blood cells.

Question 10

Which condition will lead to iron-deficiency anemia masking the diagnosis of PNH?

Accepted Answer

Iron-deficiency anemia can cause the absence of hemosiderin in urine, which is the hallmark of PNH. Therefore, in the absence of hemosiderinuria, PNH may not be diagnosed. Hemoglobinuria (A) is a symptom of PNH, so it would not mask the diagnosis. Hemoglobinemia (C) is the presence of free hemoglobin in the blood, which is a symptom of PNH, so it would not mask the diagnosis. Hemochromatosis (D) is a genetic disorder that causes excess iron absorption and could potentially increase the risk of having PNH, but it would not mask the diagnosis. Therefore, the correct answer is B.

Question 11

Which laboratory findings are associated with chronic hemolysis of PNH?

Accepted Answer

Chronic hemolysis in PNH leads to the destruction of red blood cells, which can result in low white blood cell counts (i.e. leukopenia) and low platelet counts (i.e. thrombocytopenia). Thrombocytosis, or high platelet counts, would not typically be associated with chronic hemolysis in PNH.

Question 12

When aplastic anemia occurs in conjunction with PNH, what morphological condition(s) is/are present?

Accepted Answer

Aplastic anemia is characterized by pancytopenia (reduction in all three blood cell lines) and marrow hypoplasia (reduction in the number of hematopoietic cells in the bone marrow). PNH is characterized by the presence of hemoglobinuria (red or orange urine due to the breakdown of red blood cells with subsequent release of hemoglobin into the urine). Therefore, when aplastic anemia occurs in conjunction with PNH, all three of these morphological conditions will be present.

Question 13

The defect in PNH is associated with:

Accepted Answer

PNH is caused by an abnormal clone of hematopoietic stem cells, which leads to the deficiency of GPI-linked proteins on the surface of red blood cells, white blood cells, and platelets. This results in hemolysis, thrombosis, and bone marrow failure. There is no defect in globin chains or porphyrin synthesis in PNH.

Question 14

The presentation of hemoglobinuria in a PNH patient is due to:

Accepted Answer

Hemoglobinuria in PNH is primarily due to intravascular hemolysis, where red blood cells are lysed within the blood vessels, leading to the release of free hemoglobin into the plasma, which is then filtered by the kidneys and excreted in the urine. Extravascular hemolysis, on the other hand, occurs mainly in the spleen and liver and does not result in the release of free hemoglobin into the circulation. Biphasic hemolysis is a term used to describe the combination of both intravascular and extravascular hemolysis, but it is not relevant to the presentation of hemoglobinuria in PNH. Immune hemolysis is a different mechanism that involves the destruction of red blood cells by the immune system, which is not the primary cause of hemoglobinuria in PNH.

Question 15

The definition of aplastic anemia represents what morphological characteristics?

Accepted Answer

Aplastic anemia is a condition characterized by a decrease in all types of blood cells (RBCs, WBCs, platelets) and a decrease in reticulocytes (immature RBCs). Therefore, all of the given options are correct.

Question 16

A person diagnosed with PNH may have which of the following in his or her urine?

Accepted Answer

Paroxysmal nocturnal hemoglobinuria (PNH) is characterized by hemolysis, leading to the release of hemoglobin into the urine, which can form hemoglobin casts.

Question 17

The diagnosis of PNH depends on the detection of complement-sensitive __________ in the peripheral blood.

Accepted Answer

The diagnosis of PNH is confirmed by the detection of complement-sensitive erythrocytes in the peripheral blood. PNH is characterized by the absence of glycosylphosphatidylinositol-anchored proteins on the surface of erythrocytes, making them susceptible to complement-mediated lysis. Granulocytes, platelets, and monocytes may also be affected in PNH, but the diagnosis is primarily based on the detection of PNH erythrocytes.

Question 18

Which of the following represents an acquired intracorpuscular defect?

Accepted Answer

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired intracorpuscular defect resulting from a mutation in the PIGA gene in hematopoietic stem cells, leading to a deficiency of GPI-anchored proteins on the cell surface, making red blood cells more susceptible to complement-mediated lysis.

Question 19

Schistocytes or fragmented red cells seen on a peripheral blood smear of a PNH patient may indicate:

Accepted Answer

Schistocytes or fragmented red cells are often a sign of intravascular hemolysis, which can be caused by red blood cells being destroyed as they pass through small blood vessels that have been obstructed by thrombi. Therefore, the presence of schistocytes on a peripheral blood smear of a PNH patient may indicate intravascular thrombosis.

Question 20

Which classes of PNH is deficient in both decay-accelerating factor (DAF) and membrane inhibitor of reactive lysis (MIRL)?

Accepted Answer

PNH II and PNH III are deficient in both DAF and MIRL, while PNH I is only deficient in DAF. Therefore, the correct choice is B.

Quiz 8: Aplastic Anemia Including Pure Red Cell Aplasia and Congenital Dyserythropoietic Anemia and Paroxysmal Nocturnal Hemoglobinuria