Page 44 - The Netter Collection of Medical Illustrations - Integumentary System_ Volume 4 ( PDFDrive )

Plate 2-17 Integumentary System

KELOID AND Hypertrophic scars Keloids
HYPERTROPHIC SCAR

Keloids are common benign skin tumors that consist of
excessive scar tissue that forms after trauma or inflam-
matory skin conditions such as acne vulgaris. The
keloid proliferates uncontrolled and expands beyond
the borders of the underlying scar produced by the
traumatic event. Hypertrophic scars, on the other hand,
are exuberant scar formation that stays within the con-
fines of the original scar border.
Clinical Findings: Keloids are often large over-
growths of scar tissue that expand over the original
border of the underlying scar and affect previously
normal-appearing skin. They may occur anywhere on
the body but are more common on the earlobe, chest, Hypertrophic scars do not extend One of the most common locations
and upper arms. They can affect any age group and beyond the border of the original for a keloid is the earlobe, and it can
affect males and females equally. Dark-skinned indi- injury. occur after ear piercing.
viduals have a higher incidence of keloid-type scarring.
Almost all keloids manifest after a preceding traumatic
event such as a cut, ear piercing, burn, or surgical exci-
sion. Many other causes have been found to initiate the
formation of keloids, including acne lesions and bug
bites. Keloids often start as small, red, itchy papules
that quickly enlarge into plaques and nodules. They
usually have a smooth surface with firm consistency.
Itching is a frequent complaint and often precedes the
growth stage. Keloids are diagnosed clinically in a
patient with the appropriate history. The differential
diagnosis of early keloids includes hypertrophic scars.
Difficulty sometimes arises when a patient presents
with a firm, enlarging plaque or nodule but no preced-
ing history of trauma. In these cases, a biopsy is
prudent to rule out a dermatofibrosarcoma protuber-
ans. The histopathological findings easily differentiate
the two lesions. Keloid, low power. Haphazardly arranged
Hypertrophic scars occur after trauma and are con- Hypertrophic scar, low power. Non-elevated
fined to the area of the original trauma or scar. Hyper- scar made of numerous collagen bundles, collagen bundles. Thick eosinophilic bundles of
collagen with surrounding fibroblasts
trophic scars, unlike keloids, do not grow into the fibroblasts, and blood vessels
adjacent normal skin. They can be quite large and often
are pink to red in color and pruritic. Hypertrophic scars
tend not to reach the size or extent of keloids, and for
that reason they are a bit easier to manage therapeuti-
cally. Hypertrophic scars are diagnosed clinically in a
patient with a typical history of preceding trauma and
the characteristic clinical findings.
Pathogenesis: Keloids appear to be more common in
dark-skinned individuals during the first 3 decades of
life. Keloids may have a genetic pathogenesis that has
yet to be discovered. Certain areas of the body are more
prone to keloid formation, including the chest and ear-
lobes, and there may be some local skin cytokine profile
that allows for their formation. Biological studies have
looked at various cytokines, and transforming growth
factor-β (TGF-β) has been found in elevated levels in Hypertrophic scar, high power. Numerous fibro- Keloid, high power. Thickened eosinophilic
keloids. TGF-β causes recruitment of fibroblasts into blasts with an increased number of vascular collagen bundles
the region and induces them to produce more collagen. channels. The collagen bundles are arranged
Local blockade of this cytokine may be developed as a in the same direction.
therapy in the future.
Histology: Keloids show an increase in collagen pro-
duction, and the collagen is arranged in a disorganized Treatment: Hypertrophic scars do not need to be Keloids are more challenging to treat. They have a
fashion. The overlying epidermis is typically thin due treated, because most will eventually flatten and blend high rate of recurrence after excisional removal, and for
to the mass effect of the keloid tumor pressing on the with the surrounding skin. Intralesional triamcinolone this reason adjunctive therapy should always be used after
undersurface of the epidermis, which causes attenuation may be used to help speed the process along, but care excision. Serial injections with intralesional triamcino-
of the surface epithelium. Mucopolysaccharides are should be taken not to inject too much and thereby lone monthly for 4 to 6 months may help avoid a recur-
found between the collagen fibers. cause atrophy. Daily massage by the patient has also been rence after surgery. Postoperative radiation therapy has
Hypertrophic scars are smaller and not exophytic in shown to be effective in decreasing the outward appear- also been very successful in decreasing the recurrence
nature, and the collagen bundles are arranged parallel ance of the scar. The redness of both hypertrophic and rate. There are anecdotal reports of treatment with
to the epidermis. There may be an increase in mast cells keloid scars can be treated successfully with pulsed dye imiquimod and cryotherapy, but they are of questionable
in both hypertrophic scars and keloids. laser. value.

30 THE NETTER COLLECTION OF MEDICAL ILLUSTRATIONS