A scar is a non-malignant tumour that arises at the site of healing wounds, occurring as excessively proliferated fibrous connective tissue. The lesion usually arises at the site of previous skin damage, e.g. from an extensive burn, cut, acne or surgical incision. Scar tissue is sensitive to touch and often causes pain and itching. Failure to undertake appropriate treatment can cause the scar to grow, taking the form of an unsightly growth on the skin.