A 36-year-old woman presented with weakness, lassitude, and feeling easily tired. Her bone marrow aspirate showed 15% myeloblasts and reduced erythropoiesis. The most likely cause is

Correct Answer: D

Rationale: The correct answer is D: Myelodysplastic syndrome. The patient's symptoms of weakness, lassitude, and reduced erythropoiesis along with increased myeloblasts in bone marrow are indicative of a myelodysplastic syndrome. This condition is characterized by ineffective hematopoiesis leading to cytopenias and an increased risk of progression to acute myeloid leukemia. Acute myeloid leukemia (choice A) typically presents with more aggressive symptoms and higher blast count. Acute lymphoid leukemia (choice B) primarily affects lymphoid cells, not myeloid cells. Myelofibrosis (choice C) is characterized by fibrosis in the bone marrow, leading to extramedullary hematopoiesis, which is not seen in this case.

Correct Answer: B

Rationale: The correct answer is B: Promastigote. In the laboratory diagnosis of leishmaniasis, the parasite stage typically observed in vitro is the promastigote stage. This is because promastigotes are the infective form of the parasite found in the sandfly vector. When a sample is taken from a patient, it is cultured in a suitable medium where promastigotes develop. Amastigotes (choice A) are the intracellular form found in the host, not typically observed in vitro. Trypomastigotes (choice C) are the stage found in Trypanosoma species, not Leishmania. Schizonts (choice D) are a stage in the life cycle of Plasmodium species causing malaria, not Leishmania. Promastigotes are the stage most commonly used for laboratory diagnosis and research in leishmaniasis.

Correct Answer: C

Rationale: Rationale: Hereditary spherocytosis is associated with splenomegaly due to the spleen's increased destruction of abnormal red blood cells. In this condition, red blood cells have a spherical shape, making them more prone to destruction by the spleen. Chronic renal failure (A) is not typically associated with splenomegaly. Aplastic anemia (B) is characterized by bone marrow failure and does not directly involve the spleen. Sickle cell anemia (D) leads to splenomegaly in children but not in adults due to splenic sequestration crises, making it less likely to be the correct choice.

Correct Answer: D

Rationale: The correct answer is D: SLE. Non-thrombocytopenic purpura is characterized by skin bleeding without low platelet count. SLE does not typically cause this type of purpura, as it primarily affects multiple organs through immune complex deposition. Vasculitis, uraemia, and hereditary hemorrhagic telangiectasia can all lead to non-thrombocytopenic purpura due to various mechanisms involving blood vessel inflammation, kidney dysfunction, or genetic defects in blood vessel formation, respectively.

Correct Answer: B

Rationale: The correct answer is B: lithium. Lithium does not cause hemolytic anemia because it does not affect red blood cell destruction. Penicillin (A), Quinidine (C), and Methyldopa (D) are known to cause hemolytic anemia by various mechanisms, such as immune-mediated destruction or oxidative damage to red blood cells. In contrast, lithium's mechanism of action does not involve direct harm to red blood cells, making it the correct choice in this scenario.