Fibrosis is a word pathologists use to describe what a scar looks like under the microscope. Fibrosis is made up of a special type of tissue called collagen. Collagen is made by cells called fibroblasts. When examined under the microscope, collagen looks more pink than normal tissue.
After any kind of injury, the body begins a process to repair and rebuild the damaged tissue. In many situations, the injury is completely repaired and the tissue returns to normal. In some situations, however, the body is unable to completely repair the damage and the injured tissue is replaced with a scar. Large injuries are more likely than small injuries to leave a scar.
Because fibrosis can occur in any part of the body after an injury, it is a descriptive word and not a complete diagnosis in itself. More information about the injury that caused the fibrosis is usually required to make a complete diagnosis.