My daughter age6 has a very large unexplained bruise starting just under her knee and finishing above her ankle. she has marian's syndrome.

Response: Hi Joe, Do you mean marfans syndrome? I have searched online and it looks like there may be a cross over in terms of Marian's to Marfans. If this is the case, Marfans syndrome, is a problem with connective tissue. Tissue that holds joints, stablizes blood supplies. The bruise around the knee joint maybe developing into a hematoma which is a small pocket of blood leaking into the weak tissue.

Bruise: An unexplained bruise this large needs to be examined. Please get her to a health care worker soon.