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Types of Skin Lesions

Lesions on the skin are often deeper than they appear. While some lesions are permanent or go away, some are precancerous and harmful. Read on to learn the different classifications of skin lesions.
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When an area of soft tissue in the body, is damaged or destroyed, a lesion is the sign of the damage. Any body area with vulnerable tissue can have lesions, but one of the most sensitive areas is the skin. Lesions on the skin can be formed by external causes or internal conditions.
Some lesions are harmless and are just indicators of injury or the healing process. But some types of skin lesions can cause or be a cause of skin diseases and even cancer.

Skin Lesions Types

There are 2 main categories of skin lesions: primary and secondary.
Primary Skin Lesions
Primary skin lesions are formed due to a disease or infection. They can cause a change in skin color or texture. Moles and freckles can be considered as primary lesions, which are formed at birth and not due to a disease.
Primary skin lesions are often categorized as a morphological classification of skin lesions, as this classification deals with the physical features and location of the lesions. A description of various primary skin lesions types, with their size, characteristics and causes, is given in the next slides.
Name/Feature: Macule
Size: Less than 10 mm
Color: Brown, white, red
Description: Flat, discolored
Caused By: Hives, leprosy, measles, rashes
Name/Feature: Nodule
Size: 0.5 - 2 cms
Color: None
Description: Distinct borders, hard and deep into the skin
Caused By: Inflammation, tuberculosis, roundworms
Name/Feature: Pustule
Size: Varies
Color: White, yellow, greenish-yellow
Description: Pus filled, elevated
Caused By: Bacterial infections
Name/Feature: Papule
Size: Less than 10 mm
Color: Red, pink, brown
Description: Raised, rough, solid
Caused By: Warts, syphilis, psoriasis
Name/Feature: Plaque
Size: Less than 10 mm
Color: Same as Papule
Description: Solid, elevated, flat or circular topped
Caused By: Psoriasis
Name/Feature: Bulla
Size: Greater than 1 cm
Color: Clear
Description: Fluid filled
Caused By: Burns, bites, drug reactions
Name/Feature: Wheal
Size: 3 - 4 mm
Color: Pale red
Description: Raised, rounded, flat topped
Caused By: Allergic reactions
Name/Feature: Vesicle
Size: Less than 1 cm
Color: Clear
Description: Filled with fluid, elevated
Caused By: Herpes, allergies, sunburn
Name/Feature: Tumor
Size: Greater than 2 cm
Color: None
Description: A large nodule
Caused By: No certain causes
Name/Feature: Telangiectasia
Size: None
Color: None
Description: Dilated blood vessels close to skin's surface
Caused By: Rosacea, scleroderma

Secondary Skin Lesions

If the disease or infection worsens, then primary lesions progress to secondary lesions. Some secondary lesions are caused by insistent physical contact with the infected area, like if the infected skin is repeatedly itched or nicked.
1. Scale
  • Dry or greasy in texture
  • Present on the skin in a flaky or scale-like form
  • Caused by fungal infections and psoriasis
2.Crust (Scab)
  • Can be thick and sticking to the skin or thin and easily torn
  • Serum, pus or blood which has dried and pooled on the skin
  • Part of the healing process
3.Keloids
  • Exaggerated or swollen scar tissue, that extends beyond the edges of the original wound
  • Tough and rubbery in texture, with a shiny appearance
  • Can be flesh-colored, pink or dark red in color
  • Formed from a mature scar
4.Lichenification
  • Thickening of the skin, so that the area becomes elevated
  • Visible marks appear
  • Caused by rubbing or deep scratching of an area
5. Erosion
  • Small areas of the skin, in which the upper skin layer is lost
  • Caused by various infectious skin diseases like herpes
6. Fissure
  • A narrow, deep crack on the skin, extending to the flesh
  • Caused due to excessive drying of the skin
  • Occurs at corners of the mouth and on hands and feet
7. Atrophy
  • A very wrinkled and thin area of the skin
  • Example of atrophied skin is stretch marks
  • Caused due to old age, prolonged sun exposure, strong corticosteroids creams
8. Ulcers
  • A discontinuous loss of the skin, sometimes reaching the fat layer
  • The upper portion and part of the lower portion, of the skin, is lost
  • Caused by bacterial infections or injury
9. Scars
  • Discolored tissue, that permanently replaces the skin in that area
  • Scars differ in color, depending on the skin area
  • Some scars are thick and raised, others depressed
Lesions can also be classified under their configuration style. Linear lesions are a cluster of lesions in a straight line. Annular and Nummular are ringed and circular-shaped lesion configurations. Iris lesions have rings, with a duskier or darker center group of lesions. Lesions are also a known indicator of skin cancer.
Precancerous skin lesions are lesions, which could progress into cancer, if not identified in time. The most common of all the types of precancerous skin lesions, is Actinic Keratosis. It is made up of red, scaly lesions, occurring on the face, ears and the back of the hands.
If no treatment is given, then a small portion of these lesions may develop into squamous cell carcinoma, a skin cancer.
Cutaneous horns are also precancerous. They appear as a small horn or conical lump that extend from a red skin base. These are common among elderly fair people, with a history of sun exposure. Dysplastic Nevus or Moles are cancerous, when the mole has multiple colors or uneven borders or is abnormally large.
Since, there are different types of lesions on the skin, the treatment depends on the cause. Skin lesions caused by infections, are cured by treatment of the infection itself. Allergy lesions are best solved by avoiding the allergen.
Skin preparations like creams, lotions and ointments can help in preventing infection and soothing the lesion. In some cases such as pus-filled lesions or skin cancer, a minor surgical operation might have to be performed.