<prompt> All of the following are characteristic of lymphangiomas EXCEPTRare childhood orbital tumoursTypically slow growing but may present with acute painful proptosisCalled chocolate cysts when bleeds into itselfIt is the second commonest tumour in HIV  <response>: 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. 