The phenomenon of bruising around the calf, specifically what causes it, should be considered from the following aspects. First, because the subcutaneous soft tissue fat in front of the calf tibia is relatively small, a slight bump or unintentional collision can lead to local subcutaneous bruising and the appearance of bruising and petechiae, which are found inadvertently by the patient. Secondly, it is possible that the patient’s hematologic disorders, including thrombocytopenia and lack of coagulation factors, may cause subcutaneous bruising. Again, the more common cause is thrombosis of the veins of the lower extremities, which can also cause subcutaneous bruising. Therefore, it is best to go to a regular hospital for a detailed examination, including blood routine, clotting time and some related medical examinations, to find the exact cause and carry out systematic and standardized treatment for the effective cause.