The mean cell volume of the patient is 90 fl and the reticulocyte production index is low. Which of the following is the most possible cause of anemia in this patient?

Correct Answer: C

Rationale: Rationale: A low reticulocyte production index indicates decreased bone marrow response to anemia. Aplastic anemia is characterized by bone marrow failure leading to pancytopenia, causing anemia. Thalassemia results in microcytic anemia, not macrocytic. Vitamin B12 deficiency causes macrocytic anemia due to impaired DNA synthesis. Sideroblastic anemia leads to microcytic anemia due to defective heme synthesis. Therefore, the most likely cause of anemia in this patient with a low reticulocyte production index and normal mean cell volume is aplastic anemia.

Correct Answer: A

Rationale: The correct answer is A because Burkitt's lymphoma is associated with the translocation of the c-myc gene on chromosome 8, not chromosome 18. This translocation results in the overexpression of c-myc, leading to uncontrolled cell proliferation. Choice B is incorrect as Burkitt's lymphoma commonly presents with jaw or facial bone involvement in HIV patients. Choice C is incorrect as Burkitt's lymphoma is commonly seen in African children due to Epstein-Barr virus infection, not necessarily after malaria exposure. Choice D is incorrect as Burkitt's lymphoma is histologically characterized by a "starry sky" appearance due to the presence of numerous macrophages engulfing debris from apoptotic cells.

Correct Answer: D

Rationale: Step-by-step rationale for why D is correct: 1. Koilonychias is characterized by spoon-shaped nails, a common symptom of iron deficiency anemia due to decreased hemoglobin levels. 2. Iron is essential for normal nail growth, and its deficiency can lead to changes in nail shape. 3. Hemolytic anemia (A) is characterized by the premature destruction of red blood cells, not typically associated with koilonychias. 4. Sickle cell disease (B) causes abnormal hemoglobin, leading to sickle-shaped red blood cells, not related to koilonychias. 5. Thalassemia major (C) is a genetic disorder affecting hemoglobin production, but it does not directly cause koilonychias.

Correct Answer: B

Rationale: The correct answer is B: Irradiating the blood components before transfusion. Graft versus host disease occurs when donor immune cells attack the recipient's tissues. Irradiating blood components helps to eliminate donor T cells, reducing the risk of this complication. Choice A (Transfusion of packed cells) does not address the issue of donor T cells. Choice C (Transfusing fresh whole blood) may actually increase the risk as it contains more viable donor immune cells. Choice D (Replacement by crystalloids) is not a suitable alternative for blood transfusion.

Correct Answer: C

Rationale: Step-by-step rationale: 1. Increased neutrophils, band cells, basophils, and platelets suggest myeloproliferative disorder. 2. Presence of eosinophils indicates a chronic phase as seen in chronic myelocytic leukemia. 3. Chronic myelocytic leukemia commonly presents with increased granulocytes and platelets. Summary: - A: Acute myeloid leukemia is characterized by blast cells, not mature granulocytes. - B: Acute lymphoid leukemia primarily affects lymphocytes, not myeloid cells. - D: Chronic lymphocytic leukemia involves lymphocytes, not myeloid cells like in the given case.