Fig. 1

a The dark red ecchymosis of the local skin was seen to extend from the right sulcus to the lower forehead. b The ecchymoses had dispersed to the entire right cheek and parts of the lower jaw, following which, the skin and subcutaneous tissues appeared black and were hard to the touch. c The necrotic tissue under the clam-shaped zone was removed, exposing a large tissue defect of a triangular area in the right cheek and mandibular region. d Continued physical therapy that kept the mouth opening for two hours, for a frequency of 3-4 times each day