++
Hair is a nonliving biologic fiber found everywhere on the human body
surface, with the exception of the palms, soles, glans penis, and
lateral digits. Deficient hair growth is known as hypotrichosis,
whereas hair loss is termed alopecia. Alopecia
is subclassified as scarring or nonscarring, based on the loss or
preservation of the hair follicle, respectively, and as generalized
or localized (Fig. 365-2).24In
addition, there are hair shaft abnormalities that may cause breakage
or hair loss secondary to hair fragility. Disorders of
hair in infants and children may reflect underlying biochemical
or metabolic defects in addition to immunologic disease. Tinea
capitis, the most common cause of hair loss in children, should
be considered in any pediatric patient who presents with scaling
hair loss. Untreated, long-standing tinea capitis may result
in permanent scarring alopecia with serious psychologic consequences.
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Localized Nonscarring
Alopecia
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Alopecia areata is a common, idiopathic disorder characterized
by the sudden appearance
of round or oval patches of hair loss on the scalp and other body
sites. The condition may have its onset as early as birth but usually
appears in school-age children.25 Its occasional association
with autoimmune diseases such as Hashimoto thyroiditis, myasthenia gravis,
diabetes, and vitiligo has suggested an autoimmune process. Other
associations include trisomy 21, chronic mucocutaneous candidiasis,
adrenal disease, and atopy.24
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The typical lesion of alopecia areata is a smooth, shiny, hairless,
round patch of the scalp that appears suddenly over the course of
several days. Scattered long hairs within the bald area or “exclamation
point hairs” (hairs with a narrowed proximal diameter and
often shorter length and lighter color) may be detected. Often the
nails are affected with pits and grooves giving a “Scotch plaid” appearance.25
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Two clinical forms of alopecia areata occur: patchy
alopecia areata and alopecia totalis or universalis. In the former,
a few or many patches of hair are lost and the prognosis for regrowth,
either spontaneously or with treatment, is good. If patches coalesce
into large areas with loss of more than 50% of scalp hair,
the prognosis is generally less favorable. The presence of alopecia
totalis (loss of all scalp hair) or alopecia universalis (loss of
all body and scalp hair) is a poor prognostic sign, especially in
children. Such hair loss responds poorly to treatment, and even
if hair regrows completely, recurrent episodes of alopecia totalis
are likely. In all forms of alopecia areata, new hair growth may
be lighter and finer in quality than the surrounding hair but is likely
to return to its original caliber and coloration with time.
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The diagnosis of alopecia areata is usually made clinically but
can be confirmed with a scalp biopsy in atypical cases. Classically, there
is a peribulbar lymphocytic infiltrate described as a “swarm
of bees,” whereas more chronic lesions may display less
inflammation but fibrosis and dystrophic hair shafts.24
++
Therapy for alopecia areata usually consists of topical or intralesional
corticosteroids. Localized, mild disease often responds to potent
(class I or II) topical corticosteroid therapy. Adolescents
can often tolerate the discomfort of intralesional injections of
triamcinolone acetonide (5-10 mg/cc) administered in 3-
to 4-week intervals. Systemic corticosteroids can be effective in
some patients, but high doses are often required to regrow hair,
and their discontinuation often results in recurrent hair loss.
The limited benefits and undeniable risks of systemic corticosteroids
preclude their use for alopecia areata in most instances.25
++
Other therapeutic approaches include the induction of contact
dermatitis with compounds such as anthralin, squaric acid dibutyl
ester, or diphencyprone. Pruritus, dermatitis, and staining of clothing make
this second-line therapy for the motivated patient.25 Treatment
of the pediatric patient with alopecia areata should address the
emotional needs of these children and their families. Patients with
widespread, long-standing alopecia areata may experience social
stigmatization and may benefit from hair prostheses. Several
nonprofit companies will provide quality natural hair prostheses
free of charge to patients who are in need (www.wigsforkids.org).
The National Alopecia Areata Foundation can be accessed at www.naaf.org.
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Trichotillomania is characterized by compulsive pulling,
twisting, or breaking of hair. Affected areas of the scalp demonstrate
irregularly shaped areas of partial alopecia with broken hairs of
varying lengths, giving the scalp a “moth-eaten” appearance. A
fringe of hair in the frontal area is usually left intact, as are
more inaccessible or painful parts of the occipital scalp.26 The
eyebrows or eyelashes may be pulled out instead of or in addition
to scalp hair. The differential diagnosis includes tinea
capitis, regrowing alopecia areata, and secondary syphilis. Although
the diagnosis is usually made clinically, it can be confirmed with
a scalp biopsy, which may demonstrate perifollicular hemorrhage,
absence of significant inflammation, and increased catagen hair
follicles.24 Trichotillomania may be a nervous habit
analogous to nail biting in some cases but can also indicate serious
psychopathology, particularly in older children.
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Direct confrontation and accusation are rarely helpful. Rather
than querying the patients as to whether they are engaging in hair
pulling, it is helpful to ask them when they are pulling their hair.
In addition, using the analogy to nail biting may make a frank discussion
of the problem more acceptable. Behavioral modification techniques such
as habit reversal or psychiatric evaluation should be undertaken
if the problem does not resolve or if other psychiatric symptoms are
present.26 Antidepressants and psychotropics used
for obsessive-compulsive disorder are useful adjuncts to behavioral
modification, particularly in older children.26
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Tension or pressure on the scalp can cause hair breakage or loss,
and children seem to be particularly susceptible to this problem. Traction
alopecia is fairly common in young girls who have tight
ponytails or braids. Hair thinning occurs at the scalp margin, especially
in temporal areas. Folliculitis may also be present. The problem
is most common in African American girls, often exacerbated by trichorrhexis nodosa.
If hair-styling techniques are not changed, permanent hair loss
can result.24Traumatic alopecia can result from prolonged
pressure on the scalp as might occur with general anesthesia, usually
near the vertex of the scalp. A “halo” of pressure
alopecia can also be seen after delivery in an area corresponding
to the caput succedaneum. Infants, especially those with atopic
dermatitis, are particularly susceptible to frictional hair loss
and may lose large areas of occipital and parietal scalp hair from
rubbing the head against the bed.
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Generalized Nonscarring
Alopecia
++
Telogen effluvium is a form of hair loss that
occurs after severe stress to the body, including birth, acute febrile
illness, surgical shock, crash dieting, emotional stress, or discontinuation
of oral contraceptives. Sudden stress may prematurely shift hair
shafts into the resting phase (telogen phase). Two to 3 months later, when
the anagen or growing phase of that hair shaft begins again, the telogen
hair is shed. This form of alopecia, although alarming at times,
never results in total alopecia and will resolve without intervention.24The diagnosis
can usually be made by careful questioning to identify a specific
trigger and microscopic hair examination revealing telogen hairs.
The phrase often heard is that “clumps” of hair
are falling out.25
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Androgenetic alopecia is inherited as an autosomal-dominant
trait with variable expression. In males, the mildest and earliest
feature of this alopecia is symmetric, triangular anterior hairline
recession. This pattern of hair loss is rare in the pediatric population
but has been noted as early as 14 years of age. Androgenetic alopecia
may be seen in females, but it is generally less severe than that
seen in men. The pattern of hair loss is different in females with
diffuse thinning over the crown noted, with a widened part, and
preservation of the frontal hairline.24In teenage girls
with androgenic alopecia as well as severe acne, hirsutism, and/or
menstrual irregularities, evaluation for a potential underlying
endocrine abnormality should be undertaken.24
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Loose anagen syndrome occurs most commonly in
preschool and younger school-age girls. Characteristically, the
hair is fine and lighter in color and rarely needs to be cut.24It
is usually a sporadic condition but may be inherited in an autosomal-dominant
fashion. Anagen hairs pull out easily and painlessly; on light microscopy,
they show distorted bulbs with a ruffled proximal hair cuticle.
The condition usually improves with age. There is no therapy.
++
The scarring alopecias, rare in childhood, cause permanent pilosebaceous
follicle loss and occur after trauma or infection, such as a suppurative
folliculitis or a fungal kerion. In discoid lupus erythematosus,
scarring alopecia may be preceded by erythema, hyper- and hypopigmentation,
and follicular plugging. Occasionally, pseudopelade of Brocq
may be seen in children. In this idiopathic form of scarring alopecia,
multiple round to oval scarred patches of hair loss are seen. It
is differentiated from alopecia areata by the presence of scarring.
Hairless patches may form fingerlike projections that resemble “footprints
in the snow.”24Folliculitis
decalvans is a rare form of scarring alopecia that is characterized
by multiple inflammatory papules and pustules at the periphery of
the hairless areas. The pathogenesis is complex and seems to be
secondary to both a destructive bacterial infection and a hypersensitivity
reaction.27Acne keloidalis is typically
seen in postpubertal African American males along the nape of the
neck. It may represent a hypersensitivity reaction to staphylococcal
organisms in individuals prone to keloidal scarring.27 Rarely,
localized scleroderma, especially the coup de sabre form, may form
linear plaques of scarring alopecia in children.
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Congenital Disorders with
Alopecia
++
A variety of congenital disorders may be associated with hypotrichosis
or alopecia. Temporal triangular alopecia is characterized
by a nonscarred circumscribed area of hypotrichosis in the frontotemporal
scalp (Fig. 365-3). The lesion is shaped like a
triangle or lance with the base facing the anterior edge of the
hairline and may be bilateral.28The condition is actually
a form of hypotrichosis rather than alopecia and is identified by
the presence of fine, vellus hairs within the patch. It is often
erroneously attributed to forceps injury. Adult onset temporal
triangular alopecia has also been described.29
++
+++
Hair Shaft Abnormalities
with Hair Breakage
++
Trichorrhexis nodosa is the most common cause
of hair breakage in African American patients. It frequently follows
chemical treatments and is believed to represent a genetic weakness
in the hair shaft that is unmasked by physical or chemical injury.
Although the hair is actually breaking, patients often report that
the hair has stopped growing. Examination demonstrates very short hairs,
especially on the sides of the head. Rubbing the hair between the
fingers often produces broken fragments of hair. Microscopic
examination demonstrates focal widening of the hair shaft with splaying
of the fibers, resembling two brooms with their ends pushed together. The
condition usually improves in 2 to 4 years if the hair is managed gently
by avoiding further traction, excessive heat, or chemical treatments.30
++
In pili torti, the hair shaft is twisted on
its long axis. Early in life, the hair becomes kinky and sparse
and may stand on end. Pili torti may be an isolated finding or may
occur in conjunction with several clinical syndromes. The most significant
is Menkes syndrome, an X-linked recessive, multisystem disorder
of copper metabolism. In Björnstad syndrome, associated
sensorineural hearing loss is characteristic. Crandall syndrome
consists of pili torti with hearing loss and hypogonadism.30
++
Trichorrhexis invaginata is a distinctive hair
shaft anomaly found in Netherton syndrome characterized by increased
fragility with short, sparse, lusterless hair. Under light microscopy, some
hairs may have “bamboo” or “ball-and-socket” deformities. Trichothiodystrophy
is a group of disorders in which patients have short, brittle hair
with trichoschisis (transverse fractures of the
hair), and low hair sulfur content. With polarizing microscopy,
alternating transverse bands of light and dark are seen. The typical “tiger
tail” pattern of the hair shaft in trichothiodystrophy
may not be evident at birth. Monilethrix (beaded
hair) is a rare structural hair abnormality caused by mutations
in hair cortex keratin.30 The hair is lusterless and brittle, failing
to grow more than a few centimeters in length. Keratosis pilaris,
mental retardation, abnormal nails and teeth, and cataracts may
occur in association.
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Hair Shaft Abnormalities Without
Breakage
++
Patients may display woolly hair that differs
from that of family members or other uninvolved areas of the scalp.
The hair is tightly curled, and hairs are oval in cross sections.
Autosomal-dominant and autosomal-recessive forms have been described.
Woolly hair may be associated with keratosis pilaris atrophicans,
Noonan syndrome, dilated cardiomyopathy, palmoplantar keratoderma
with cardiac conduction defects, giant axonal neuropathy, and osteoma cutis.
Localized areas of woolly hair represent woolly hair nevi. They
are usually sporadic and may be associated with epidermal nevi in
continguity or, more often, on another area of the body. Ocular involvement
has also been described.30
++
In uncombable hair syndrome (pili trianguli
canaliculi or spun glass hair syndrome) hair is light blonde, frizzy,
and cannot be combed flat. It often glistens or is spangled in appearance.
Eyebrows, lashes, and body hair are normal. Under microscopy, the hairs
are triangular or kidney shaped in cross section, although these
changes are not specific for this syndrome.30 Reports suggest
both autosomal-dominant and -recessive inheritance, and this may
be seen in conjunction with other disorders.