58) A well-appearing 6-year-old presents to your office with a | Paediatrics videos & books

58) A well-appearing 6-year-old presents to your office with a chief complaint of bruising. The parents report that the child had a cold 2 weeks ago but completely recovered. The child is sitting on the examining table, in no distress, discussing her favorite cartoons. On examination, you find mucosal bleeding and bruises on the child’s arms and chest. You order a complete blood count (CBC) that has the following results: WBC 12,000, hemoglobin 11 g/dL, and a platelet count of 45,000. What is the most likely cause of this child’s bleeding and bruising?