Medicine. Bodily tissue which has been structurally changed due to disease or injury and usually occurs as or includes a fissure, wound, or other break in the tissue. Lesions can occur in various parts of the body such as the skin and other organs. The simplest definition is "a wound or injury". Additional Info: Skin lesions are abnormal growths or areas of skin that do not resemble the normal skin surrounding them. Examples include cysts, nodules, papules, polyps, pustules, vesicles and wheals. Lesions not caused by injury can potentially be malignant, so always have any unusual lesions assessed by your doctor. MSDS Relevance: Exposure to corrosive chemicals and irritants can cause skin lesions (wounds), while others can cause lesions, tumors or ulcers on the internal organs on chronic (long-term) exposure. Take steps to minimize your exposure to all chemicals and know the hazards of those that you work with. Be sure to use proper engineering controls such as ventilation or fume hoods if available, and personal protective equipment such as gloves or chemical protective clothing. See also: Dermatitis, Edema, Erythema, Urticaria, Vesicant