The fibrosarcoma is a rare cancer, it is the subtype of soft tissue sarcomas and often starts from the soft issue. In many cases, it would occur in the mouth. This cancer is aggressive, and it would erode the skin and the bone (upper jaw bone). The surgery could remove it, but the trauma is complicate and unhealing. By the way, this cancer could start from any part of the body, and the animals like dogs and cats could also affected.