This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pediatrics
[{'content': 'Microscopy of a specimen shows "pawn ball megakaryocytes". This patient may have: \nSelect and explain. \nA. Myelodysplastic syndrome, B. Idiopathic thrombocytopenic purpura, C. Thrombotic thrombocytopenic purpura, D. Chloramphenicol toxicity', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Myelodysplastic syndromes (MDS) are a group of clonal stem cell disorders characterized by maturation defects associated with ineffective erythropoiesis and a high risk of transformation to AML. The most characteristic finding is disordered differentiating affecting all three lineages i.e., erythroid, myeloid, and megakaryocytic. Erythroid lineage effects: Ringed sideroblasts,that is erythroblasts with iron-laden mitochondria visible as perinuclear granules on Prussian blue stain Megaloblastoid maturation, resembling that seen in vitamin B12 or folate deficiency Nuclear budding abnormalities, producing misshapen nuclei Granulocyte lineage effects: Neutrophils with decreased numbers of secondary granules, toxic granulations, or Dohle bodies Pseudo-Pelger-Huet cells (neutrophils with only two nuclear lobes) Myeloblasts may be increased but account for less than 20% of overall marrow cellularity Megakaryocytic lineage effects: Megakaryocytes with single nuclear lobes or multiple separate nuclei ("pawn ball" megakaryocytes Ref: Pocket Companion to Robbins & Cotran Pathologic Basis of Disease By Richard Mitchell, Vinay Kumar, Nelson Fausto, Abul K. Abbas, Jon C. Aster, 8th edition, Page 334-335.', 'role': 'assistant'}]