Hi Idiopathic thromocytopenic purpura is one of the main cause of bruise Diseases of the platelets which are the particles in the blood which form small plugs and prevent bleeding- can be a decrease in the number called thrombocytopenia or defect in their ability to stick to one another and form a plug - called thrombasthenia Several diseases can cause thrombocytopenia There can be disease of liver and certain other diseases that decrease the clotting factors and lead such bleeding. It ought to be investigated with a complete blood count, Prothrombin time and other clotting factors Apply Ice and Cabbage leaves on the bruise area, which will reduce the inflammation If you still have any queries please feel free to contact HCM Wish You Good Health Regards Dr Sridhar K