What causes pain and bruise on the thigh?
Patient: I am a very active 34 y/o male but I can not recall having any trauma to the posterior side of my left thigh. I awoke today to pain in said area, I looked and saw a cluster of about 10 bruises, none bigger than a quarter size and some as small as a dime. Doctor: Alteration in the coagulation cascade /clotting factors in blood can cause such conditions even without significant trauma. Certain diseases, drugs such as anticoagulants,antiplatlets,NSAIDS,etc can cause so. U may need to get a blood work up to ascertain the cause. Most of the time it may be of no underlying pathology and  left alone..