Learn more about the 9 most common food allergies. A rash resembling large purple patches or dark bruises can indicate a serious condition, such as vasculitis and deep vein thrombosis. A medical ...

Medically reviewed by Archana Sharma, DO Although rare, a red rash may indicate leukemia, which is a type of blood cancer. A ...

Henoch-Schonlein purpura (HSP) produces a distinctive rash on a child's arms, legs, and buttocks that looks like bruises ...