This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Haematology, Subject name: Medicine
The parents ofa 13-month-old boy are contacted by a local social agency because the day care repoed them for suspected child abuse based on "too may bruises." The parents deny the abuse and promptly arragne to have their child seen by a medical specialist. The child has multiple large bruises on his legs, anus, and buttocks. No skin abrasions and no "pattern marks" are seen. PTT is prolonged and PT and bleeding time are normal. Which of the following is the most probable 
Select and explain. 
A. Acute myelogenous leukemia, B. Disseminated intravascular coagulation, C. Vitamin K deficiency, D. Von Willebrand disease
D: Von Willebrand disease
Answer: D: Von Willebrand disease 
Explanation: Von Willebrand disease usually presents with haemorrhagic manifestations like superficial bruising, epixtasis, menorrhagia and gastrointestinal haemorrhage are common. This condition is caused by quantitative(type 1&3) or qualitative(type2) deficiency of Von Willebrand factor. This protein is synthesised by endothelial cells and megakaryocytes. Reference : Davidson, 23rd Edition, page no : 974.