A lesion is any damaged or abnormal area of tissue in the body. Since they happen in so many different places and types of tissue, they have many different causes and means of diagnosis and treatment. Most lesions are broadly categorized by where they appear in the body — for example, skin and mouth lesions are some of the most common types — but there are also site-specific ways of categorizing them. The effects of any particular area of abnormality depends on its placement, type, and size.
Skin lesions can be either primary, which means that they cause a variation in color or texture of the affected skin; or secondary, which includes things like the scabbing that naturally forms on an abrasion or peeling that follows a sunburn. Moles, birthmarks, warts, and hives are all common primary types, while skin ulcers, scabs, fissures, and lichenification are all common secondary types. Skin abnormalities can also be categorized by size, appearance, and whether they are cancerous or non-cancerous.
As this type of damage can be caused by so many different things, the way they're treated varies. If they're caused by an infectious disease, then doctors generally try to treat the underlying condition rather than the lesions themselves. Sometimes topical antibiotics can help prevent further infection. Other topical treatments, such as cortisol cream, can be applied to soothe itchy or irritated skin. In many cases, treatment for harmless skin damage is primarily cosmetic: for example, patients may resort to laser surgery to reduce the appearance of a mole.
Though the vast majority of skin lesions are harmless, some can be an indicator of skin cancer. Moles or birthmarks that have an uneven edge or have a change in color may be cancerous, particularly if they are larger than 0.19 inches (5 mm) in diameter.
Oral lesions include any type of tissue abnormality in the mouth, like dental caries or cavities, herpes blisters, ulcers, gingivitis, and inflammation from yeast infections. People who smoke or chew tobacco are more likely than those who do not to get some types of oral problems, including oral cancers and hairy tongue. Good dental hygiene can be very effective in preventing many types of oral lesions.
As with skin damage, the treatment for oral abnormalities is generally focused on treating the underlying cause. Some oral conditions can be treated, like gingivitis and yeast infections, but others, like herpes blisters, cannot be fully cured. For conditions that can be treated, dentists may advise patients to use medicated mouthwashes, gels, and toothpastes, as well as tongue scrapers for conditions like hairy tongue. Lesions that affect the inner tissues of the mouth, like oral cancer, may be surgically removed. Debridement, a procedure in which dead tissue is removed, may also be used when the tissue is severely damaged, along with antibiotics to control infection.
Brain lesions are associated with a range of conditions, including Alzheimer's disease, meningitis, multiple sclerosis, and cerebral palsy. Tumors, physical trauma, and aging can also cause this type of damage, as can bleeding, like that from a stroke. Environmental factors, like exposure to toxins, can also cause brain abnormalities. Some remain small enough that they don't cause any symptoms. If this is the case, doctors often take a wait and see approach, monitoring the area to make sure that it doesn't start to cause damage, and treating it if it does.
Depending on the cause of the damage, doctors may be able to treat some types of brain lesions. For example, a brain abscess can often be treated with antibiotics or antifungal medications. Other abnormalities can cause permanent damage. Though there are sometimes ways to treat the symptoms caused by the damage, as in the case of a stroke, damage caused by other conditions, like Alzheimer's disease, are progressive and not treatable. The location of the damage can also have an impact on the treatment — for example, it's often more difficult to treat tumors that are deep in the brain than those that are closer to the surface.
Most lung lesions are caused by either bacterial or viral illnesses or cancer. Sometimes cysts, holes, or scar tissue can form in the lungs as well. There are also several types of congenital lung abnormalities, including Congenital Cystic Adenomatoid Malformation (CCAM) and lung sequestrations. One of the most common types of lung lesion is a Solitary Pulmonary Nodule (SPN), which is typically a benign tumor, but can be malignant in about one in five cases. Tuberculosis also causes lung lesions, which may reactivate after treatment and cause another round of the disease.
Many people with this type of lung problem don't know they have it, and only find out when they get a diagnostic test like Magnetic Resonance Imaging (MRI) done for another condition. There are a variety of treatments available for these abnormalities, ranging from surgery and chemotherapy in the case of cancer to antibiotics in the case of tuberculosis. Not smoking and avoiding environmental factors like air pollution and asbestos can help prevent this type of lung damage.
People can get a lesion essentially anywhere they can get a tumor, so the liver, pancreas, genitals, intestines, kidneys, bones, eyes, and gallbladder can all be affected as well. Kidney and pancreas cysts are particularly common. Cells and molecules can also get lesions, as in the case of sickle-cell disease.