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Acne keloidalis
introduction
Cicatricial alopecias are an enigmatic group of hair disorders
linked by the potential for permanent loss of scalp hair follicles
in involved areas. Progress in our understanding and treatment of
these disorders has been hindered by the lack of clear diagnostic
criteria for the various hair loss entities. Since all these dangerous
hair loss conditions evolve as the hair is destroyed or replaced,
diagnosis is further made difficult by an overlap of clinical and
pathologic features of the various conditions.
Although the condition was first described by Kaposi as “dermatitis
papillaris capillitii” in 1869, the term we currently use
for this scarring alopecia, acne keloidalis, was coined by Bazin
in 1872. This inflammatory condition is most often seen in African
American men with curly hair, though that is not to say that black
women and Caucasians cannot be affected. The disease is also known
as acne keloidalis nuchae, dermatitis papillaris capillitii, sycosis
nuchae, and folliculitis keloidalis, and is classified as a mixed
alopecia by the North American Hair Research Society. Alopecias
that cannot be designated as “lymphocytic” or “neutrophilic” have
been classified as “mixed” alopecias by NAHRS.
Acne keloidalis presents as firm follicular papules (a small circumscribed,
superficial, solid elevation) that are concentrated in the lower
back part of the head and skull (the occiput). In the initial stages
of the disease, hairs protrude from the papules. As the disease
progresses, the papules join together into hairless keloid -like
plaques. A keloid is a red, raised formation of fibrous scar tissue.
The presence of abnormal extensive tunnels called sinuses and abscesses
(collection of pus formed by tissue destruction) are also found.
Many authors consider the term acne keloidalis a misnomer, as the
condition is neither a kind of acne nor keloidal in nature. Although
the etiology of the disease remains shrouded in mystery, hair fiber
curling into the skin or damage to scalp skin from frequent shaving
has been suggested to be the underlying cause of the disease. Mechanical
trauma from shirt collars, scratching and seborrhea (over activity
of the sebaceous glands) appear to aggravate the condition. Other
possible precipitants identified include infection with Demodex,
a genus of parasitic, usually nonpathogenic, mites that invade the
skin and are often found in the sebaceous glands /hair follicles
of many people. Due to the location of papules on the occipital
scalp where curly hair is cut closely, the theory that acne keloidalis
is related to ingrown hairs has been entertained, but there is lack
of strong, supportive evidence.
Acne keloidalis or Folliculitis keloidalis has all the features
of primary scarring alopecia. Many of the histolological findings
in Acne keoidalis are also similar to central centrifugal scarring
alopecia (CCSA). This may or may not indicate a related pathogenesis.
Acne keloidalis
clinical features
Onsets of Folliculitis keloidalis or acne keloidalis normally occurs
after adolescence and prior to age 50. Outside of this age range
it is extremely rare for the disease to develop. Areas of involvement
are typically the occipital part of the scalp and the nape of the
neck, though it is not unusual to find the vertex and parietal scalp
are also affected. The eruptions occur in the form of a raised transverse
band at the lower margin of the hairy scalp. The band is hairless
except at its upper margin, which is abrupt, broken into nodules
and fringed with hair in tufts, like bunches of bristles in a brush.
The initial papules of the condition are soft to firm, flesh colored
to reddish brown, smooth follicular pin points. Further, into the
disease the papules may be crusted, umbilicated (having a central
mark or depression resembling a navel) or pustular (small swellings
similar to blisters or pimples) and contain hair.
Although Folliculitis keloidalis is largely asymptomatic, patients
normally complain of itching and burning. Pustules, abscesses, sinuses,
foul smelling discharge and pain are also sometimes seen in this
form of alopecia. In some more severe cases, the papules coalesce
to form nodules or cosmetically disfiguring keloidal plaques. In
extreme cases, large hardened tumors may also form.
Acne keloidalis
differential diagnosis
The firm follicular based papules of acne keloidalis are so distinctive
that an experienced dermatologist should not have a problem identifying
the disease. Though, at times the clinical presentation can also
mimic early folliculitis decalvans.
Acne mechanica, conventional folliculitis, and molluscum contagiosa
need to be distinguished from acne keloidalis. Acne mechanica is
a form of acne that develops in response to heat, covered skin,
constant pressure, and/or repetitive friction against the skin.
Molluscum contagiosa is growth on the skin which looks like white
pearls, caused by a group of viruses.
The tendency of dissecting cellulitis to cause severe alopecia,
fluctuant nodules, and sinus tracts helps to distinguish acne keloidalis
nuchae from dissecting cellulitis.
There are occasional cases of Acne keloidalis similar to central
centrifugal scarring alopecia with manifestation of numerous follicular
papules concentrated on the vertex of the scalp with few occipital
lesions. In such cases, the lesional presentation is of Acne keloidalis,
but the distribution is of CCSA.
Acne keloidalis
pathology
Histopathological analysis (the study of microscopic changes in
diseased tissues) of the different stages of disease suggests that
in persons with a predisposition to the condition, there is progressive,
locally destructive folliculitis, which triggers repeated cycles
of acute and granulomatous inflammation with reparative fibrosis.
The most consistent histologic findings in a study of 19 biopsies
(a procedure that involves obtaining a tissue specimen for microscopic
analysis to establish a precise diagnosis) taken from 10 African
American patients under study were;
- perifollicular, chronic (lymphoplasmacytic) inflammation, most
pronounced at the level of the isthmus (middle segment of the
hair follicle) and lower
infundibulum (upper segment of the hair follicle)
- lamellar fibroplasia
(formation of fibrous tissue), most prominent at the level of
isthmus
- loss of the sebaceous glands associated with inflamed
follicles
- thinning of the follicular epithelium at the level
of the isthmus
- total epithelial destruction with remnants of “naked” hair
fragments
- dilation of the follicular canal.
- Premature desquamation (shedding)
of the inner root sheath was found in a minority of specimens.
- Only small numbers of Demodex organisms and no evidence of bacterial
infection were found.
- Even some clinically normal specimens
showed significant histologic abnormalities, including total
destruction of individual follicles.
This observation suggests that even normal appearing skin is affected by the
scarring
process
in acne keloidalis.
The explanation for these histological findings as supplied by
researchers in the field is that the acute inflammation, whether
it begins in the sebaceous gland or elsewhere in the region of the
hair follicle infundibulum or isthmus, is a cause or the result
of a weakened follicular wall at these points. This enables the
release of the hair fiber shafts into the surrounding skin dermis.
These "foreign" (because they would not normally be found
in the dermis) hairs, incite a further acute and chronic granulomatous
inflammation from the body’s immune system. The localized
granulomatous inflammation manifests itself clinically as a papular
lesion at the skin surface. Fibroblasts, which are spindle-shaped
cells capable of forming collagen fibers, lay down collagen and
scars form in the region of the inflammation. Distortion and closing
of the follicular lumen (the tube in the center of a hair follicle
thorugh which the hair fiber passes) by fibrosis leads to hair retention
in the follicle and causes further inflammation and scarring.
Characteristically, early lesions are typified by a perifollicular
and intrafollicular inflammatory cell infiltrate that is particularly
pronounced at the level of the sebaceous gland. The isthmic follicular
epithelium may be thinned and lamellar fibroplasia evident. As the
disease progresses, complete follicular destruction occurs. The
scarring and granulomatous inflammations are exhibited as keloid-like
scars and plaques. Sinus tracts are uncommon in acne keloidalis.
Acne keloidalis
treatment
This chronic condition is unlikely to abate without treatment.
A clear diagnostic framework of general clinical and histological
presentations in the early, mid and late stage of the disorder can
help reach a conclusive diagnosis before significant and irreversible
follicular destruction has occurred. Correct recognition of the
condition allows for the early institution of therapy, which is
the best chance for effective intervention. Documentation is indicative
that women have a better response to treatment.
The treatment approach to acne keloidalis is usually based on the
severity of presentation. The following has been observed:
- Since this condition appears to be a scarring alopecia,
early mild disease responds to class I or II topical steroids
alone or in combination with topical antibiotics.
- The Papular
stage of the disease responds favorably to monthly intralesional
triamcinolone acetonide, alone or in combination with topical or oral
antibiotics.
- Adjunctive use of antibacterial soaps has also been
seen to help.
- Based on limited studies, topical and oral retinoids,
a class of chemical compounds that are related chemically to
vitamin A, have not been successful
in the treatment of Folliculitis keloidalis.
- Similarly, cryotherapy
alone or in combination with rifampin (a bactericidal drug)
appears to elicit little response.
- In cases where the condition
has progressed to a scarred keloidal plaque, surgical intervention
may be required. Popular approaches include
excision with primary closure or secondary intention healing. Primary healing,
or first
intention,
is the least complex as it refers to the healing together of the
edges of clean, closely opposed wound edges. Secondary healing or second intention
involves
not only apposition of edges, but also the filling of the soft
tissue defects. In fact, with very big lesions, better results
have been reported with
staged
incision and primary closure as against wound healing by secondary
intention.
- Many different techniques have been reported in the surgical
treatment of acne keloidalis including CO2 laser excision and
excision with
subsequent skin grafting.
Folliculitis keloidalis or acne keloidalis is a chronic inflammatory
condition of the occipital scalp most frequently seen in African-American
men. As with most scarring alopecias, aggressive and early intervention
is necessary to halt the inflammatory process. In patients who progress
to end-stage disease, surgical intervention with appropriate techniques
can be utilized to achieve excellent results.
Acne keloidalis
references
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