This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Orbital Disorders, Subject name: Ophthalmology
[{'content': "All of the following are characteristic of lymphangiomas EXCEPT \nSelect and explain. \nA. Rare childhood orbital tumours, B. Typically slow growing but may present with acute painful proptosis, C. Called 'chocolate cysts' when bleeds into itself, D. It is the second commonest tumour in HIV", 'role': 'user'}, {'content': "Answer: D \nExplanation: Commonest tumor in HIV is kaposi sarcoma. 2nd commonest tumor is lymphoma, not lymphangioma. Lymphangioma-. It is an uncommon tumour presenting with slowly progressive proptosis in a young person. It often enlarges because of spontaneous bleed within the vascular spaces, leading to formation of 'chocolate cysts' which may regress spontaneously.", 'role': 'assistant'}]