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Lichen
planopilaris introduction
Diagnosing cicatricial (scarring) alopecia can be rather difficult,
as the nomencalture covers a broad spectrum of hair disorders, some
of which share the same clinical features like permanent destruction
of the hair follicle and irreversible hair loss. In scarring alopecia
disorders, immediate diagnosis and therapeutic intervention are
crucial. Lichen planopilaris (follicular lichen planus) is one such
alopecia condition, and is classified as a primary inflammatory
scarring alopecia.
Classic lichen planopilaris (LPP) is a variant of lichen planus,
a common skin disease that affects other areas of the body skin
away fro mthe scalp. Lichen planopilaris affects the hairy areas
of the body, causing inflammation, hair loss, and scarring. It
is considered as a variant of lichen planus as it follows the
same
development pattern as classic lichen planus.
Lichen planopilaris is characterized by variable yet prominent
follicular changes. In some cases, the disease leads to permanent
hair loss
though this is not always the end result and some people can have
a mild form of the disease where the hair follicles are not irreversibly
destroyed. Lichen planopilaris presents primarily in middle-aged
women, but there are case reports detailing lichen planopilaris
in individuals as young as 13 years old. Although the etiology
is unknown, certain immuno-pathological mechanisms could be the
root
cause of the skin condition.
This type of alopecia exhibits primarily as skin flaking, hair
loss and pruritis. The alopecia caused by lichen planopilaris
presents
as distinct patches of hair loss that may expand and coalesce
over time. The condition develops very slowly, so much so that
even after
several years of the disease the patches of hair loss may be
small and inconspicuous.
Lichen
planopilaris clinical
features
Lichen planopilaris also known as follicular lichen planus, is
manifested by tiny red spiny papules around a cluster of hairs.
Sometimes even blistering occurs in the lesions. In some cases,
no follicular scaling or inflammation is present but bald areas
of scarring slowly appear.
Lichen planopilaris is similar to pseudopelade with respect to
patchy scarring alopecia, with greater degree of inflammation, and
presence of other cutaneous and mucosal lesions. In rare cases,
the disease progresses at a rapid pace; the involvement of the surrounding
areas in such cases result in a considerable amount of hair loss.
The primary lesion is a polygonal, flat-topped, shiny papule with
retained skin lines. The papules tend to cluster in streaks. Fine
adherent scales may appear on the surface of the lesion in the later
stages. Dilated hair follicles may be plugged with keratin. Common
areas of scalp involvement include the central scalp and crown,
but the entire scalp is rarely involved.
Classic lichen planopilaris presents as itchy, multifocal or central
alopecic patches with follicular hyperkeratosis or hardening and
erythema or redness at the hair-bearing margin. Progressive frontal
fibrosing alopecia is a clinically distinct variant of lichen planopilaris
that affects in particular elderly women and frequently involves
the eyebrows. The basis for this tissue reaction targeting frontal
scalp follicles and eyebrows is unknown.
Lichen
planopilaris differential
diagnosis
Evaluating patients with lichen planopilaris is quite a challenge
from the diagnostic aspect. The histological and clinical overlapping
between the different forms of cicatrical alopecias can cause confusion
in distinguishing lichen planopilaris from systemic lupus erythematosus
and frontal fibrosing alopecia. Some dermatologists claim that lichen
planopilaris is the same as pseudopelade; however, the majority
of dermatologists are of the opinion that there are subtle distinctions
between the two disorders.
Although lichen planopilaris is a distinct form of scarring alopecia,
it can be rather difficult to diagnose with certainty. When accompanied
by characteristic lesions of lichen planus on the skin and oral
mucosa, lichen planopilaris is easily ascertained. Very often, however,
the scalp is the only part of the body affected, causing confusion
in diagnosis.
Diagnosis of lichen planopilaris can be confused with Pseudopelade
of Brocq at times. When a ‘squamatized’ basal layer
and interfollicular changes of lichen planus are present, the diagnosis
of lichen planopilaris is supported. Biopsy specimens showing an
interface dermatitis confined to the follicles can be confused with
cutaneous lupus erythematosus.
Therefore, early scalp lichen planopilaris cannot be easily distinguished
from other forms of scalp alopecia. Disease activity is limited
to the hair-bearing periphery of cicatrized alopecia, and pustules
are absent in this kind of alopecia. Features of end-stage lichen
planopilaris can mimic other primary cicatricial alopecias, making
it difficult to reach a proper diagnosis.
Lichen
planopilaris pathology
The histological hallmark of lichen planopilaris is a chronic perfollicular
and interface dermatitis that affects the hair follicle infundibulum
(the segment that extends from the entrance of the sebaceous gland
duct to the follicular orifice) and isthmus (the short segment that
extends from the insertion of the erector pili muscle to the entrance
of the sebaceous gland duct). This leads to destruction of basal
keratinocytes in the hair follicle. Keratinocytes compose most of
the epidermis and are responsible for producing a protein, keratin,
which helps protect the skin and the underlying tissues from heat,
microbes, abrasion and chemicals.
Scalp biopsies are critical for the assessment and diagnosis of
scarring alopecia and are often employed when identifying Lichen
planopilaris. The inflammatory infiltrates in the perifollicular
connective tissue sheaths affect the follicular epithelium in a
manner similar to that affecting the epidermis of non-follicular
lichen planus. The keratinized product in the lumen (the central
canal where the hair fiber usually grows) of the affected follicle
is usually dense orthokeratin. The lumen of the follicle is dilated,
the follicle is plugged and the granular layer of the infundibulum
is accentuated. The hair follicle reverts to a phase from which
it does not recover. The perifollicular inflammation and fibrosis
produces progressive attrition of the follicular epithelium. The
follicle eventually atrophies, leaving, as a marker, a linear band
of fibrous tissue as a trace of the perifollicular connective tissue
sheath. This is all that remains of the original hair follicle.
Biopsy specimens from patients with clinically active lichen planopilaris
will reveal that lichenoid interface alteration disrupts the epithelial-adventitial
dermal junction. The presence of an intact inner root sheath of
hair follicles excludes the diagnosis of central centrifugal cicatricial
alopecia. As lesions mature, the outermost layer of the follicular
epithelium becomes ‘squamatized’ and the basilar epithelium
is destroyed. This results in what is referred to as “Max
Joseph” spaces or artifactual clefting between the epithelium
and the dermis. An end stage of the disease is characterized by
longitudinal tracts of fibrosis at the sites of former follicles,
with accompanying adjacent epidermal atrophy or destruction and
papillary fibrosis (formation of fibrous scar tissue).
Due to sampling error or poor site selection in biopsy, very often
the only changes that can be identified are perifollicular chronic
inflammation and fibroplasia. These changes are non-specific and
do not point assertively to lichen planopilaris unless supported
by typical lesions of lichen planus on other sites of the body.
In many cases where non-specific changes are found, additional biopsies
and clinical information is required to arrive at the correct diagnosis.
The Verhoeff-van Gieson (VVG) elastin stain is of value in differentiating
lichen planopilaris from other types of alopecia, which present
common pathologic characteristics, but display distinct patterns
of tissue staining.
Lichen
planopilaris treatment
Detailed history, thorough physical examination and interpretation
of appropriate laboratory procedures like scalp biopsy are crucial
to the correct diagnostic conclusion and commencement of therapy.
A thorough examination of the entire scalp can give valuable indications
in differentiating the pathological condition.
Therapeutic management of lichen planopilaris is not simple. Lichen
planopilaris should be treated as quickly as possible to avoid permanent
hair loss. Treatment is case- dependant, as severity of symptoms,
extent of the lesions and response to treatment vary from individual
to individual.
All patients manifesting symptoms of lichen planopilaris should
undergo assessment for a possible drug related source for the disease.
If a drug or chemical is the suspected cause of the lichen planopilaris,
the drug should be discontinued and the chemical avoided.
Documentation on treatment of lichen planopilaris is limited and
do not provide adequate details on number of patients treated, duration
of treatment, doses administered, and corresponding results. In
general, local disease is managed by topical steroids but very often,
potent topical and intralesional steroids are found to be ineffective.
The long-term use of anti malarial drugs in the treatment of lichen
planopilaris may be somewhat effective. The uses of anti-T cell
compounds such as cyclosporine have aroused interest, but their
harmlessness and efficacy in the management of lichen planopilaris
is yet to be established.
Retinoids, a class of chemical compounds that are related chemically
to vitamin A, have demonstrated some effect in the treatment of
lichen planopilaris. Use of systemic medications should be restrained
and only given to those individuals with local steroid-refractory,
rapidly progressive or symptomatic scalp lichen planopilaris. Short
tapered courses of prednisone can often be effective as combination
therapy with retinoids or antimalarials. Anti malarials have been
propounded as a first line treatment, but these provide symptomatic
relief only. In studies of patients, mixed outcomes have been reported
with treatment with low molecular weight heparin and thalidomide.
The above treatment options do come with their share of side effects.
It is therefore imperative that the side effects be weighed against
the benefits on a case-to-case basis, and close monitoring of the
patient should undoubtedly be an integral part of the treatment
regimen.
Diagnosis of lichen planopilaris cannot be made using clinical
features alone, and convincing cases of lichen planopilaris include
a combination of typical lichen planus lesions and scarring alopecia.
Those cases presenting only as scarring alopecia of scalp require
histological co-relation for convincing diagnosis.
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planopilaris references
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