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A lesion is any abnormal tissue found on or in an organism, usually damaged by disease or trauma. Lesion is derived from the Latin word laesio which means injury.

ons are caused by any process that damages tissues. A cancerous tumor is an example of a lesion, however the surrounding tissue damaged by a tumor is also a lesion. Trauma
Physical trauma

Physical trauma refers to a body injury. A trauma patient is someone who has suffered serious and life-threatening physical injury with the potential for secondary complications such as Shock , respiratory failure and death....
, including electrocution and chemical burns can also cause lesions.






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A lesion is any abnormal tissue found on or in an organism, usually damaged by disease or trauma. Lesion is derived from the Latin word laesio which means injury.

Causes of lesions

Lesions are caused by any process that damages tissues. A cancerous tumor is an example of a lesion, however the surrounding tissue damaged by a tumor is also a lesion. Trauma
Physical trauma

Physical trauma refers to a body injury. A trauma patient is someone who has suffered serious and life-threatening physical injury with the potential for secondary complications such as Shock , respiratory failure and death....
, including electrocution and chemical burns can also cause lesions. Certain diseases present lesions, for example the skin deformities caused by chicken pox. Lesions can also be caused by metabolic processes, like an ulcer or autoimmune activity, as in the case with many forms of arthritis
Arthritis

Arthritis is a group of conditions involving damage to the joints of the body. Arthritis is the leading cause of disability in people older than fifty-five years....
.

Lesions are sometimes intentionally inflicted during neurosurgery
Neurosurgery

Neurosurgery is the surgery discipline focused on treating those central nervous system, peripheral nervous system and spinal column diseases amenable to surgical intervention....
, such as the carefully-placed brain lesion used to treat epilepsy
Epilepsy

Epilepsy is a common chronic neurological disorder characterized by recurrent unprovoked seizure s. These seizures are transient signs and/or symptoms of abnormal, excessive or synchronous neuronal activity in the brain....
 and other brain disorders. (See Ablative brain surgery
Ablative brain surgery

Ablative brain surgery is the surgery ablation by burning or freezing of brain tissue to treat neurological disorder or psychological disorder disorders....
.)

Note that lesions are not limited to animals or humans; damaged plants are said to have lesions.

Types of lesions

Because the definition of lesion is so broad, the varieties of lesions are virtually endless. They are subsequently classified by their features. If a lesion is caused by cancer it will be classified as malignant versus benign. Lesions may be classified by the shape they form, as is the case with many ulcers, which can have a bullseye
Bullseye (target)

The bullseye is the center of a target , and by extension the name given to any shot that hits the bullseye. There is a common misconception that the bullseye in darts is worth 25, however the green outer bullseye of the dart board is actually worth half of the bullseye ....
 or 'target' appearance. Their size may be specified as gross or histologic depending on whether they are visible to the unaided eye or require a microscope to see.

An additional classification that is sometimes used is based on whether or not a lesion occupies space. A space occupying lesion, as the name suggests, occupies space and may impinge on nearby structures, whereas a non space occupying lesion is simply a hole in the tissue, e.g. a small area of the brain that has turned to fluid following a stroke
Stroke

A stroke is the rapidly developing loss of brain function due to a disturbance in the blood supply to the brain. According to the National Stroke Association, a "stroke" occurs when a blood clot blocks and artery or a blood vessel breaks, interrupting blood flow to an area of the brain....
.

Some lesions have specialized names, like the Gohn lesions in the lungs of tuberculosis victims. The characteristic skin lesions of a varicella-zoster virus (VZV) infection are called chickenpox
Chickenpox

Chickenpox or chicken pox is a highly contagious illness caused by primary infection with varicella zoster virus . It generally begins with a vesicular skin rash appearing in two or three waves, mainly on the body and head rather than the hands and becoming itchy raw pockmarks, small open sores which heal mostly without scarring....
. Lesions of the teeth are usually called dental caries
Dental caries

Dental caries, also known as tooth decay, is a disease where bacterial processes damage hard tooth structure . These tissues progressively break down, producing dental cavities ....
.

Finally, lesions are often classified by their location. For example, compare a 'skin lesion' versus a 'brain lesion'.

See also


  • Ablation
    Ablation

    Ablation is defined as the removal of material from the surface of an object by vaporization, chipping, or other erosion processes. The term occurs in space physics associated with atmospheric reentry, in glaciology, medicine and passive fire protection....
Neonatal hypo-glycemia may result in lesions in the brain which may further induce hyperactivity in children.

External links

  • Differential Diagnosis of Brain Lesions