Folliculitis
keloidalis nuchae
Salient features
·
Begins as a chronic folliculitis of
the occipital scalp and nape of the neck
·
With time, keloidal papules and
plaques develop
·
Vast majority of affected
individuals are men of African descent
Introduction
Folliculitis
keloidalis nuchae (FKN) is a relatively common chronic inflammatory process
involving principally the hair follicles that leads to hypertrophic
scarring papules, plaques, and alopecia on the occiput
and/or nape of the neck. The patients usually
develop a chronic folliculitis and perifolliculitis of the posterior scalp and
neck, which then heals with keloid-like papules. Over time, these papules may
coalesce to form one or several large plaques, which gradually enlarge over a
period of years. The lesions are usually pruritic and may also be painful and
cosmetically disfiguring. The sooner the condition is treated, the less likely
it will become disfiguring.
Epidemiology
Age
Folliculitis keloidalis occurs in males after
puberty and is most frequent between the ages of 14 and 25 years. Development
prior to puberty or after the age of 50 years is extremely rare.
Sex
Males are most commonly affected.
Folliculitis keloidalis may occur in women, but the male: female ratio is at
least 20: 1.
Ethnicity
FKN is a potentially
disfiguring follicular disorder that is primarily seen in men of African
ancestry who have Afro-textured hair, followed in
frequency by Hispanics, Asians and, least often, Caucasians.
Pathogenesis
The etiology of FKN
remains incompletely understood. In one study,
two-thirds of affected patients had concomitant seborrheic dermatitis and
one-third had concomitant pseudofolliculitis barbae. No specific organism has
been firmly implicated in the etiology but Staphylococcus aureus may commonly be
isolated from swabs from affected skin. FKN usually occurs in men with
frequent (at <2 week intervals) and close
haircuts. It may also occur in women who shape the hair of the posterior neck
with a razor. Shapero and Shapero hypothesized that FKN is initiated by a
mechanically induced folliculitis that becomes extensive enough to result in
scar formation. Based on a histopathologicstudy, Sperling and colleagues argue
that FKN is a primary cicatricial alopecia that is not causally associated with
ingrown hairs or bacterial infection. Reported contributory factors to FKN
include trauma, chronic irritation, seborrhea, infection, and chronic low-grade folliculitis. Sources of
mechanical irritation that may exacerbate or potentially contribute to the
development FKN include friction from high-collared shirts, sports helmets, and
other garments or equipment. In a study of Nigerian patients by George and
colleagues, the nape of the neck/occipital scalp was found to have an increased
(almost double) number of mast cells compared with the anterior scalp. The
large number of mast cells in this location may contribute to a pruritic
sensation prompting rubbing and manipulation of the skin, thereby predisposing this location to the development of FKN.
Genetic predisposition may also influence the density of mast cells in
the scalp.
Clinical features
FKN often begins as a
chronic folliculitis on the occipital scalp and nape of the neck, followed by
the development of 2–4 mm, dome-shaped, firm
follicular papules. Pustules and/or crusted papules can also be
observed, especially when secondary infection occurs. Pruritus is common, and
patients frequently admit to scratching or rubbing the affected areas. Pustules are usually short-lived because they are traumatized
when the hair is combed or brushed or are easily ruptured by scratching. In
contrast to acne vulgaris, comedones are not present.
As the disease progresses, more hard papules
develop and slowly enlarge. Some papules coalesce and form hairless keloid-like plaques or nodules which are often arranged in a band-like distribution near
the posterior hairline. The plaques are usually only a few centimeters in
diameter but may grow to more than 10 cm. Even when only papules are present, a
large portion of the occipital scalp may be involved.
When the
area of involvement is significant, there is usually patchy alopecia or
complete hair loss. Occasionally, the scarring process may extend onto the
vertex and/or parietal scalp. The upper borders of large lesions are often
fringed with tufted hairs that resemble the hair on a doll’s head (multiple hair
shafts emerging from a single follicular opening). Severe secondary infections
can result in subcutaneous abscesses with draining
sinuses that may emit a malodorous discharge. The condition is extremely
chronic and new lesions may continue to form at intervals for years.
Pathology
Inflammation
begins around the isthmus and lower infundibulum of the hair follicle.
Descriptions of the initial infiltrate vary from it being composed of
neutrophils and lymphocytes to predominantly plasma cells. Sebaceous glands are
markedly diminished or absent in all stages of the disease. In more advanced
lesions, hair follicles are disrupted, and fragments of naked hair shafts
surrounded by granulomatous inflammation may be noted. Dermal fibrosis is also
present at this stage, and the collagen fibers resemble those seen in scar
tissue rather than those seen in keloids. The lower portion of the follicle,
including the matrix, is usually spared until later in the disease process.
Actual keloid formation can be seen in late stages.
Early in the disease
there is follicular dilatation with neutrophils, and follicular rupture with
perifollicular abscesses.
Late lesions show perifollicular granulomas around naked
hair shafts mixed with lymphoplasmacellular cell infiltrate, and hypertrophic
scar with broad eosinophilic hyalinized keloidal collagen bundles.
Disease course and prognosis
The
condition usually becomes chronic with permanent keloidal scarring.
Investigations
Skin
swabs can be taken if bacterial infection is suspected.
Management
The first step in the management of FKN is
initiating preventive measures to minimize disease progression or exacerbation.
Those who have FKA should not wear any kind of
head-dress or head gear that causes mechanical irritation of the posterior
hairline. In addition, they should neither edge their posterior hairline with a
razor nor wear shirts or sweaters that irritate the posterior scalp and neck.
Bacterial
infection should be treated if present; and the use of topical antimicrobial
cleansers (eg, chlorhexidine or povidone iodine) to prevent secondary
infection.
The
sooner therapy is initiated the less likely the patient is to develop large
lesions. Mild
to moderate cases of FKN can be improved with the use of potent and ultrapotent
topical corticosteroids that may reduce inflammation
and scarring. Topical therapies are generally sufficient when the
papules are 3 mm or smaller and no nodules are present. To prevent atrophy and
other side effects of corticosteroids, an alternating 2-week cycle (i.e., 2
weeks on, 2 weeks off) of clobetasol propionate 0.05% foam twice daily for 8
weeks followed by 4 weeks of betamethasone valerate 0.12% foam twice daily if
lesions persisted demonstrated significant decreases in papule/pustule counts
at week 12. Twice-daily application of a tretinoin
gel and a mid- to high-potency corticosteroid gel may be sufficient to relieve
all symptoms and flatten existing non-inflamed lesions.
Topical
or systemic antibiotics, as for acne vulgaris, may clear the inflamed pustules but
do not soften or clear the secondary keloidal lesions. Topical clindamycin
gel or foam can be used in conjunction with topical corticosteroids, especially
when pustules are present. Oral doxycycline or minocycline are useful for
extensive cases because of their anti-inflammatory and antimicrobial effects
(in cases of secondary infection).
For larger papules 20 to 40 mg/mL
triamcinolone acetonide intralesionally can be
injected into the keloidal papules, but if they persist, they often need to be
removed by a punch excision with a hair transplant trephine followed by either
a primary closure or healing by second intention. The punch must extend below
the level of the hair follicle to be successful. In addition, a 50: 50 mixture
of 2% lidocaine (with epinephrine [adrenaline]) and triamcinolone acetonide
(40 mg/ml) can be used for local anesthesia in order to help prevent
recurrence. If the patient sleeps on his or her back or has a short neck, then
the lesions can be closed with silk sutures to prevent stiff suture ends from
piercing the skin. One week after suture removal, the excision sites are
injected with triamcinolone acetonide (40 mg/ml), and this can be performed
three more times at 3-week intervals. A bacterial culture should be obtained
from any site with oozing or drainage, followed by treatment with the
appropriate systemic antibiotic.
For
plaques 1.0–1.5 cm in vertical diameter, excision with primary closure is the
treatment of choice. Some claim that daily topical imiquimod, starting
immediately postoperatively and continuing for 6–8 weeks, may prevent
recurrence. If the imiquimod causes irritation, then it should be discontinued
for a few days and subsequently applied every other day for a total of 8 weeks.
Lesions
>1.5 cm in vertical diameter should not be closed primarily, because the
postoperative scar usually spreads to the width of the excisional defect,
producing a hairless flat scar. For these lesions, the area of FKA is excised
to the level of the fascia or deep subcutaneous tissue and left to heal by
second intention. The excision must include the posterior hairline within the
surgical ellipse. It normally takes 8–12 weeks for the defect to close.
Corticosteroids are not injected into these sites because they may prevent
wound contracture.
Some patients have been successfully treated
with CO2 laser excision, but it requires postoperative
triamcinolone injections (10–40 mg/ml) every 3 weeks for four sessions,
starting 2 weeks after the laser procedure.
Laser‐assisted hair removal with the long‐pulsed Nd:YAG laser and diode lasers led to significant reductions
in papule count, plaque count, and plaque size in patients with FKN. The laser causes miniaturization of the hair shafts,
which is thought to reduce subsequent inflammatory episodes.
Cryotherapy
is also sometimes useful, but it requires freezing for 30–40 seconds. In
individuals with darkly pigmented skin, freezing for more than 25 seconds may
cause hypopigmentation (which can last 12–18 weeks) or even depigmentation.
Following
surgical procedures, intralesional or potent topical corticosteroids (e.g. gel,
foam), alone or in combination with oral or topical antibiotics, can be
used, as well as a tretinoin–corticosteroid gel mixture. Based upon case
reports, a course of oral isotretinoin may prove helpful in recalcitrant
inflammatory cases of FKA.
Treatment of FKN by disease severity
