Block 10 Pathology RBC Labs

1. A 23-year old woman presents to her family physician with fatigue. She also states that her urine looks "cola-colored" when she first goes to the bathroom in the morning. Blood work-up shows a pancytopenia. The patient's RBCs are mixed with acidified normal serum and compared to normal RBCs at room temperature and at 37C. Both temperatures cause the patient's, but not the normal, RBCs to lyse. Based on the clinical information provided and the laboratory tests, which of the following is the most likely diagnosis?

Aplastic anemia

Megaloblastic anemia

Myelodysplastic syndrome (MDS)

Paroxysmal nocturnal hemoglobinuria (PNH)

Fanconi anemia

Based on the clinical information provided and the laboratory tests, the most likely diagnosis is paroxysmal nocturnal hemoglobinuria (PNH). PNH is a rare acquired disorder of the hematopoietic stem cells characterized by intravascular hemolysis, bone marrow failure, and venous thrombosis. The patient's fatigue, cola-colored urine, and pancytopenia are consistent with PNH. The acidified serum test is used to detect the presence of the PNH clone, as PNH RBCs are sensitive to lysis in an acid environment. The fact that the patient's RBCs lyse at both room temperature and 37C suggests the presence of PNH.

Explanation

Based on the clinical information provided and the laboratory tests, the most likely diagnosis is paroxysmal nocturnal hemoglobinuria (PNH). PNH is a rare acquired disorder of the hematopoietic stem cells characterized by intravascular hemolysis, bone marrow failure, and venous thrombosis. The patient's fatigue, cola-colored urine, and pancytopenia are consistent with PNH. The acidified serum test is used to detect the presence of the PNH clone, as PNH RBCs are sensitive to lysis in an acid environment. The fact that the patient's RBCs lyse at both room temperature and 37C suggests the presence of PNH.

2. A 56-yr-old man presents to his primary care physician and reports having a blood problem, mentioning a recent diagnosis of myelophthisic anemia. He does not seem to understand his diagnosis and wants to know what causes this disorder. His physician immediately orders labs and explains that his condition is usually caused by a problem located in the

Bone marrow

Kidneys

Liver

Pancreas

Spleen

Myelophthisic anemia is a type of anemia that occurs when the bone marrow is replaced by abnormal cells, such as cancer cells or fibrosis. This replacement disrupts the normal production of blood cells, leading to anemia. Therefore, the correct answer is bone marrow, as this is the site where the problem causing myelophthisic anemia is located.

Explanation

Myelophthisic anemia is a type of anemia that occurs when the bone marrow is replaced by abnormal cells, such as cancer cells or fibrosis. This replacement disrupts the normal production of blood cells, leading to anemia. Therefore, the correct answer is bone marrow, as this is the site where the problem causing myelophthisic anemia is located.

3. A 30-year-old woman complains of constant fatigue. Physical examination reveals pallor and a palpable spleen tip. PBS shows spherocytes. Osmotic fragility is increased. An inherited abnormality in which of the following best accounts for these findings?

Alpha-globin chain

Beta-globin chain

Membrane skeletal protein

G6PD

Synthesis of heme

C. Correct.
Spectrin and related proteins (protein 4.1, ankyrin) are cytoskeletal proteins that are important is maintaining the RBC shape.

Explanation

C. Correct.
Spectrin and related proteins (protein 4.1, ankyrin) are cytoskeletal proteins that are important is maintaining the RBC shape.

4. Which of the following is most likely to show microcytic, hypochromic red cells and a low MCV?

A habitual alcoholic with acute withdrawal symptoms

A patient with chronic gastric ulcer

A patient who has taken methotrexate

A patient with SLE and reticulocytosis

. Correct. Chronic gastric ulcer would result in a gastro-intestinal blood loss that would cause an iron deficiency anemia, with a low MCV and microcytic hypochromic red cells.

Explanation

. Correct. Chronic gastric ulcer would result in a gastro-intestinal blood loss that would cause an iron deficiency anemia, with a low MCV and microcytic hypochromic red cells.

5. A 32-yr-old female comes to the physician because of a sore throat, worsening fatigue, and shortness of breath for the past 3 days. She has a history of migraines for many years. Her temperature is 38.6°F (101.5°F) and her pulse is 100/minute. A CBC shows hemoglobin of 10 g/dL, hematocrit of 30%, and 1,500 WBC/cmm. Platelet count is 50,000/cmm. The corrected reticulocyte count is <1%. Which of the following is the most likely diagnosis?

Iron deficiency anemia

Megaloblastic anemia

Aplastic anemia

Sideroblastic anemia

The patient's presentation of worsening fatigue, shortness of breath, sore throat, and low hemoglobin and hematocrit levels indicate anemia. The low platelet count suggests bone marrow suppression. The corrected reticulocyte count being less than 1% indicates inadequate production of red blood cells, which is characteristic of aplastic anemia. This condition is often caused by immune-mediated destruction of hematopoietic stem cells or exposure to certain drugs or toxins. Iron deficiency anemia is characterized by low hemoglobin, but the reticulocyte count is usually elevated. Megaloblastic anemia is characterized by macrocytic red blood cells and can be caused by vitamin B12 or folate deficiency. Sideroblastic anemia is characterized by abnormal iron metabolism and ringed sideroblasts in the bone marrow.

Explanation

The patient's presentation of worsening fatigue, shortness of breath, sore throat, and low hemoglobin and hematocrit levels indicate anemia. The low platelet count suggests bone marrow suppression. The corrected reticulocyte count being less than 1% indicates inadequate production of red blood cells, which is characteristic of aplastic anemia. This condition is often caused by immune-mediated destruction of hematopoietic stem cells or exposure to certain drugs or toxins. Iron deficiency anemia is characterized by low hemoglobin, but the reticulocyte count is usually elevated. Megaloblastic anemia is characterized by macrocytic red blood cells and can be caused by vitamin B12 or folate deficiency. Sideroblastic anemia is characterized by abnormal iron metabolism and ringed sideroblasts in the bone marrow.

6. A 2-yr-old boy is brought to the emergency department because of shortness of breath and left-sided abdominal pain for 3 hrs. He appears pale. Physical examination shows hypotension and tachycardia. There is splenomegaly with the spleen tip palpated 8 cm below the costal margin. Lab studies show Hb - 5.1 g/dL (N: 12.1-14.9) Hematocrit - 16% (N: 37-44.4%) Leukocyte count- 4500/cmm (N: 4000-11,500) Platelet count - 87,000/cmm (N: 150,000-400,000) A photomicrograph of a Wright-stained peripheral blood smear is shown. Which of the following is the most likely cause of this patient's current condition?

Aplastic crisis

Splenic sequestration

Congestive heart failure

Auto-immune hemolysis

Salmonella sepsis

The patient presents with shortness of breath, left-sided abdominal pain, pale appearance, hypotension, tachycardia, and splenomegaly with the spleen tip palpated 8 cm below the costal margin. Lab studies show low hemoglobin, hematocrit, and platelet count. These findings are consistent with splenic sequestration crisis, which occurs in patients with sickle cell disease. In this condition, sickled red blood cells become trapped in the spleen, leading to splenic enlargement and pooling of blood, resulting in an acute drop in hemoglobin and hematocrit levels. This can cause hypotension and tachycardia. Therefore, the most likely cause of this patient's current condition is splenic sequestration.

Explanation

The patient presents with shortness of breath, left-sided abdominal pain, pale appearance, hypotension, tachycardia, and splenomegaly with the spleen tip palpated 8 cm below the costal margin. Lab studies show low hemoglobin, hematocrit, and platelet count. These findings are consistent with splenic sequestration crisis, which occurs in patients with sickle cell disease. In this condition, sickled red blood cells become trapped in the spleen, leading to splenic enlargement and pooling of blood, resulting in an acute drop in hemoglobin and hematocrit levels. This can cause hypotension and tachycardia. Therefore, the most likely cause of this patient's current condition is splenic sequestration.

7. A 13-yr-old boy is brought to the emergency department because of a fall from the skateboard. An x-ray of the skull is shown here. Which of the following hematological conditions is the most likely cause of these findings?

Acute lymphoblastic leukemia (ALL)

Megaloblastic anemia

Iron deficiency anemia

Sickle cell anemia

Multiple myeloma

The x-ray of the skull shows the presence of "hair-on-end" or "crew-cut" appearance, which is a characteristic finding in patients with sickle cell anemia. This appearance is caused by marrow expansion due to increased erythropoiesis in response to chronic hemolysis and anemia. Acute lymphoblastic leukemia (ALL) may cause bone marrow infiltration, but it typically does not present with the "hair-on-end" appearance. Megaloblastic anemia is characterized by macrocytic red blood cells, which would not explain the findings on the x-ray. Iron deficiency anemia and multiple myeloma do not typically cause the "hair-on-end" appearance.

Explanation

The x-ray of the skull shows the presence of "hair-on-end" or "crew-cut" appearance, which is a characteristic finding in patients with sickle cell anemia. This appearance is caused by marrow expansion due to increased erythropoiesis in response to chronic hemolysis and anemia. Acute lymphoblastic leukemia (ALL) may cause bone marrow infiltration, but it typically does not present with the "hair-on-end" appearance. Megaloblastic anemia is characterized by macrocytic red blood cells, which would not explain the findings on the x-ray. Iron deficiency anemia and multiple myeloma do not typically cause the "hair-on-end" appearance.

8. Which of the following is most likely to show microcytic, hypochromic red cells and a low MCV?

Pernicious anemia

Gastro-intestinal blood loss

Folate deficiency

Warm auto-immune hemolytic anemia

B. Correct. Gastro-intestinal blood loss would result in an iron deficiency anemia, with a low MCV and microcytic hypochromic red cells.

Explanation

B. Correct. Gastro-intestinal blood loss would result in an iron deficiency anemia, with a low MCV and microcytic hypochromic red cells.

9. A 54-year-old woman with a long history of iron deficiency anemia now presents with progressive dysphagia (difficulty swallowing) primarily with solid foods. On examination, she has swollen, painful, smooth appearing tongue (glossitis) and spooning of her nails (koilonychia). Endoscopy reveals she has a large esophageal web, which has been obstructing her food passage. Her most likely diagnosis is

Fanconi anemia

Lead poisoning

Esophageal cancer

Plummer-Vinson syndrome

Thalassemia

D. Correct. Esophageal web, koilonychia and iron deficiency anemia are features of Pulmmer-Vinson syndrome

Explanation

D. Correct. Esophageal web, koilonychia and iron deficiency anemia are features of Pulmmer-Vinson syndrome

10. A 55-yr-old man visits his physician for a routine physical examination. Other than occasional fatigue, he reports feeling well. CBC shows low hemoglobin values and microcytic hypochromic red cells. Which of the following serum values would suggest that the physician should next take a stool sample for analysis?

↑ MCV and hyper-segmented neutrophils

↑ reticulocyte count and abnormal hemoglobin EP

↑ Serum ferritin

↑TIBC and low MCV

D. Correct. Stool for occult blood is used for screening colon cancer. Any elderly patient with a suspected iron deficiency should be investigated by stool analysis. Iron deficiency is suggested by the findings of increased TIBC and low MCV.

Explanation

D. Correct. Stool for occult blood is used for screening colon cancer. Any elderly patient with a suspected iron deficiency should be investigated by stool analysis. Iron deficiency is suggested by the findings of increased TIBC and low MCV.

11. A 25-year-old black male sickle cell patient was brought to the ER because of fever and chest pains for the past 24 hours. His anemia was unchanged. His reticulocyte count was 10%. The most likely cause of his acute problem is

Aplastic crisis

Vaso-occlusive crisis

Sequestration crisis

Severe iron deficiency

Vitamin B12 deficiency

The most likely cause of the 25-year-old black male sickle cell patient's acute problem is a vaso-occlusive crisis. This is indicated by the patient's symptoms of fever and chest pains, which are common manifestations of vaso-occlusive crises in sickle cell disease. Additionally, the fact that the patient's anemia was unchanged suggests that the crisis is not due to aplastic crisis or severe iron deficiency. Vitamin B12 deficiency and sequestration crisis are less likely causes based on the given information.

Explanation

The most likely cause of the 25-year-old black male sickle cell patient's acute problem is a vaso-occlusive crisis. This is indicated by the patient's symptoms of fever and chest pains, which are common manifestations of vaso-occlusive crises in sickle cell disease. Additionally, the fact that the patient's anemia was unchanged suggests that the crisis is not due to aplastic crisis or severe iron deficiency. Vitamin B12 deficiency and sequestration crisis are less likely causes based on the given information.

12. A 31-year-old woman has a low-grade fever for the past one week. Physical examination reveals pallor. She has a history of chronic anemia. PBS shows spherocytosis. Her reticulocyte count is very low. Which of the following events is most likely to have occurred in this patient?

DIC

Reduced erythropoiesis from parvovirus B19 infection

Accelerated extravascular hemolysis in the spleen

Development of anti-RBC antibodies

B. Correct.
The patient has an aplastic crisis, precipitated by parvovirus infection in a patient suffering from chronic hemolytic anemia (hereditary spherocytosis).

Explanation

B. Correct.
The patient has an aplastic crisis, precipitated by parvovirus infection in a patient suffering from chronic hemolytic anemia (hereditary spherocytosis).