What Are Keloids

In general, a keloid is an abnormal connective tissue response to a wound or inflammation due to surgery, burns, or some other traumatic skin condition that causes a sore (e.g., acne or chickenpox). Cosmetic appearances, itchiness, pain, and pressure are primary concerns for people with keloids.1,3

Different than other scar tissue, keloids are benign tumors that usually extend to adjacent tissues beyond the wound region.2 They can feel soft or rubbery and hard, and when they first form tend to be red but fade over time.3 Keloids often do not have hair follicles or secretory glands.3 Although it is sometimes difficult to determine whether a scar is a keloid or not in the early stages, there are other visible and microscopic differences between keloids and hypertrophic scars as well:1,5



Dermatologists often categorize keloids into different types by where they appear on the body, causes, and treatment methods. Some of these are:

Type Cause or Prevalence Location & Description
Post-incisional keloids Following surgery, most common
in Caucasian population.2
Typically in areas that are frequently stretched
or flexed (e.g., chest, shoulder, back) with the
exception of palms and soles.2
Ear lobe keloids Mostly as a result of ear piercing
but also other trauma; greater
risk of occurrence in children under age 11.2,7
Shiny and smooth, these scars can take a number
of globular shapes in different areas of the ear
lobe and other parts of the outer ear.2 However,
they are more common on the back of the lobe.7
Spontaneous keloids Unidentified past trauma or inflammation;
occasionally linked to malignancy.2
Thickened, dense, fibrous raised nodules on the
skin surface anywhere on the body.8
Acne keloidalis nuchae (AKN) Chronic irritation and inflammation of hair
follicles usually related to friction from close
shaving, collars, or helmets and minor infection;
typically in African-American males or others over
age; scarring of ingrown hairs typically 50.2,8
Scalp and nape of neck; individual raised round
bumps may join together to form keloid/keloid-like nodules.2
Perifolliculitis capitis Almost always occurs in adult men
(ages 18-40) and more commonly in
African-Americans; chronic inflammation
of the hair follicles.8
Firm and painful nodules on the scalp that often
join together in ridges; accompanying hair loss
and discharge of pus.8
Sessile keloids Any skin trauma.2 These flattened, thick lesions can occur anywhere
on the body.2
Acne Usually occurs as deep inflammatory
acne lesions heal, but can develop with
less severe lesions in people prone to keloids.10

Acne patients treated with isotretinoin along
with argon laser or dermabrasion.11
Anywhere on the face and body that acne occurs.10
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Some authorities believe that AKN is not a true keloidal condition but
rather a separate condition with hypertrophic scarring.
Dissecting cellulitis of the scalp.
A derivative of vitamin A; commonly known by one of its brand names,
Accutane™, which is no longer sold in the United States.
Argon lasers have a different wavelength than pulsed dye or CO2
lasers sometimes used to treat keloids.