Hi, I can understand your concern for bruise over right shin bone. Regarding the problem of bruises which we call medially as purpuric or ecchymotic spots is common condition seen due to multiple causes. To guide you elaborately- Bruise or the purpura is simply formed due to extravasation and collection of red blood cells from the vessels under the skin. This results in formation of reddish spots which we call as Bruise in simple language. There are multiple of factors causing extravasation of red blood cells from the vessels- 1. Due to trauma to the small blood vessels of the skin. 2. Due to some problem in the platelets ( the cells which prevents the extravasation of red blood cells from the vessels and forms the clot). 3. Due to problem with the coagulation factors which helps in repair of the injury to blood vessels and helps in clot formation. 4. Due to combination of all these factors. For the best part of the diagnosis there are simple tests of platelet function and coagulation factors done routinely in all the simple laboratories to rule out the exact cause of the problem. If these tests are normal then you can rest assured and relieve your tensions regarding the rash. Otherwise also if the test are abnormal then also can be very well treated without any problem. Take care.