Abhimelech, a 58-year-old male, comes to the clinic reporting headaches, dizziness, and pruritus, particularly after warm baths. Upon examination, he appears plethoric, with a ruddy complexion. His medical history includes hypertension, managed with medication, but no other significant conditions. Laboratory tests reveal an elevated hemoglobin level of 18.5 g/dL, hematocrit of 57%, and red blood cell count of 6.2 million per microliter, leading to a suspicion of polycythemia. Further tests confirm low erythropoietin levels, normal oxygen saturation, and the presence of the JAK2 V617F mutation, which is pathognomonic for polycythemia vera (PV). Of the following, which vitamin levels are strikingly elevated in patients with polycythemia vera?

A 58 year-old male comes to your office reporting headaches, dizziness, tinnitus, vertigo, blurred vision, and easy bruising. He feels miserable after a warm shower because his whole body itches intensely. In a dinner party last weekend, his nose bled profusely. His fingers and toes become red, painful with burning sensations and warmth. He takes low-dose aspirin for relief from the pain and redness. His past medical history is significant for deep venous thrombosis in the right lower extremity 3 months ago. He has a history of smoking one or two cigarettes a day for over 10 years. His temperature is 99 °F (37.2 °C), heart rate is 108 beats/min, blood pressure is 164/105 mm Hg, respirations are 19 breaths/min, and oxygen saturation is 99% on room air. Physical examination is remarkable for engorged retinal veins, tenderness in the epigastric region (probably due to peptic ulcer disease) and splenomegaly. Laboratory results are given below: Erythrocyte count (RBC) 7.9 million/mm³ Male: 4.3 – 5.9 million/mm³ Female: 3.5 – 5.5 million/mm³ Hematocrit 61% Male:41% – 53% Female: 36% – 46% Hemoglobin, blood 21 g/dL Male:13.5-17.5 g/dL Female 12.0 – 16.0 g/dL Hemoglobin A₁c 5.6% ≤6% Leukocyte count (WBC) 16,754 /mm³ 4500-11,000/mm³ Neutrophils, segmented 84% 54% – 62% Neutrophils, bands 12% 3% – 5% Eosinophils 7% 1% – 3% Basophils 3% 0% – 0.75% Platelet count 1,200,000 /mm³ 150,000 – 400,000/mm³ Iron 63 µg/dL Male: 65 – 175 µg/dL Female: 50 – 170 µg/dL Total iron-binding capacity 410 µg/dL 250 – 400 µg/dL Transferrin 385 mg/dL 200 – 360 mg/dL Erythropoietin (EPO) 6.8 mg/dL 2.6 – 18.5 mg/dL Vitamin B12 1750 pg/mL 160 – 950 pg/mL Carboxyhemoglobin 2.7% <2.5% Uric acid 8.9 mg/dL 3.5 - 7.2 mg/dL Bone marrow film shows hypercellular marrow with erythroid, granulocytic, and megakaryocytic hyperplasia without overt dysmorphia of cells and normal maturation sequence, normal RBC, WBC, platelet morphology. Prussian blue stain reveals absence of iron. Which of the following mutations is detectable in blood myeloid cells of this patient?

A 61 year-old male comes to your office reporting headaches, dizziness, tinnitus, vertigo, blurred vision, and easy bruising. He feels miserable after a warm shower because his whole body itches intensely. In a dinner party last weekend, his nose bled profusely.  His fingers and toes become red, painful with burning sensations and warmth. He takes low-dose aspirin for relief from the pain and redness. His past medical history is significant for deep venous thrombosis in the right lower extremity 3 months ago. He has a history of smoking one or two cigarettes a day for over 10 years.  His temperature is 99 °F (37.2 °C), heart rate is 108 beats/min, blood pressure is 164/105 mm Hg, respirations are 19 breaths/min, and oxygen saturation is 99% on room air. Physical examination is remarkable for engorged retinal veins, tenderness in the epigastric region (probably due to peptic ulcer disease) and splenomegaly. Laboratory results are given below:  Erythrocyte count (RBC) 7.9 million/mm³ Male: 4.3 – 5.9 million/mm³ Female: 3.5 – 5.5 million/mm³ Hematocrit 61%  Male:41% – 53% Female: 36% – 46% Hemoglobin, blood 21 g/dL  Male:13.5-17.5 g/dL Female 12.0 – 16.0 g/dL Hemoglobin A₁c 5.6% ≤6% Leukocyte count (WBC) 16,754 /mm³ 4500-11,000/mm³ Neutrophils, segmented 84% 54% – 62% Neutrophils, bands 12% 3% – 5% Eosinophils 7% 1% – 3% Basophils 3% 0% – 0.75% Platelet count  1,200,000 /mm³ 150,000 – 400,000/mm³ Iron 63 µg/dL Male: 65 – 175 µg/dL Female: 50 – 170 µg/dL Total iron-binding capacity 410 µg/dL 250 – 400 µg/dL Transferrin 385 mg/dL  200 – 360 mg/dL  Erythropoietin (EPO) 6.8 mg/dL  2.6 – 18.5 mg/dL  Vitamin  B12 1750 pg/mL  160 – 950 pg/mL Carboxyhemoglobin 2.7% <2.5% Uric acid  8.9 mg/dL  3.5 - 7.2 mg/dL   Bone marrow film shows hypercellular marrow with erythroid, granulocytic, and megakaryocytic hyperplasia without overt dysmorphia of cells and normal maturation sequence, normal RBC, WBC, platelet morphology. Prussian blue stain reveals absence of iron.  What is the most likely diagnosis in this patient?

A 12-year-old boy presents to the pediatric clinic with fatigue, recurrent nosebleeds, and easy bruising over the past month. His parents report he has been less active recently and noticed pale skin. There is no history of recent illness, medication use, or significant environmental exposures. His family history reveals a maternal uncle who died of bone marrow failure in his teens. You suspect aplastic anemia in this boy. As you prepare for a physical examination, you wonder about possible positive findings in this patient. Which of the following is not seen in aplastic anemia and its presence should suggest an alternative diagnosis?

A 12-year-old boy presents to the pediatric clinic with fatigue, recurrent nosebleeds, and easy bruising over the past month. His parents report he has been less active recently and noticed pale skin. There is no history of recent illness, medication use, or significant environmental exposures. His family history reveals a maternal uncle who died of bone marrow failure in his teens. On examination, the boy appears pale and has petechiae on his lower limbs but no lymphadenopathy or hepatosplenomegaly. Laboratory studies reveal pancytopenia, with low hemoglobin, platelets, and white blood cell counts. Bone marrow biopsy shows hypocellular marrow with fat replacement, consistent with aplastic anemia. Genetic testing identifies a mutation, confirming the diagnosis of a hereditary form of aplastic anemia. What is the most common hereditary cause of aplastic anemia?

A 32-year-old female with no significant past medical history except for a recent upper respiratory infection treated with antibiotics, presents with symptoms of fatigue, frequent infections, and unexplained bruising. Over the last few months, she noticed increased shortness of breath upon minimal exertion and an unusual tendency to bruise easily after minor bumps. Her symptoms escalated to include prolonged bleeding from minor cuts, leading her to seek medical attention. Initial blood work revealed severe pancytopenia with a hemoglobin of 7.5 g/dL, white blood cell count of 1.2 x 10^9/L, and platelets at 20 x 10^9/L. A bone marrow biopsy was conducted due to the suspicion of bone marrow failure. The biopsy confirmed the diagnosis of aplastic anemia, showing a hypocellular marrow with increased fat spaces and decreased hematopoietic cells. Which of the following can cause aplastic anemia?

A 25-year-old woman presented with fatigue, shortness of breath, and easy bruising. Her complete blood count revealed pancytopenia, characterized by a significant decrease in red blood cells, white blood cells, and platelets. A bone marrow biopsy confirmed severe hypocellularity, consistent with aplastic anemia. Further investigations, including viral serology, revealed a recent viral infection that can cause transient bone marrow suppression in immunocompetent individuals. Which of the following viruses can cause aplastic anemia?

A 26 year-old woman presents to your office and reports feeling usually weak and tired, having trouble concentrating, shortness of breath, especially with activity, pounding sensation in the ears, easy bruising from minor injuries and even brushing her teeth, frequent nosebleeds, heavy menstrual periods, and tiny red spots on her arms. Her past medical history is significant for three urinary tract infections in the last four months. She has no prior exposure to chemicals and reports no drug use. In physical examination, you notice a well-built, well dressed woman with no distress. She has pallor of conjunctiva, the skin and mucous membranes. There are petechiae and ecchymosis on both arms. She has resting tachycardia. You did not notice lymphadenopathy and splenomegaly. Suspecting a blood disorder, you ordered some laboratory tests. The results are as follows. Laboratory results: Neutrophil count: 498//μL; platelet count 19700/μL; hemoglobin 8.2 g/dl; corrected reticulocyte count 0.9% blood smear showed large erythrocytes with increased mean corpuscular volume (MCV). Paucity of platelets and granulocytes. No reticulocytes. Normal lymphocytes. Bone marrow biopsy: readily aspirated, mainly fatty biopsy specimen, markedly hypocellular devoid of marrow progenitors Which of the following is the most likely diagnosis?