Nail lichen planus
Salient features
|
· Nail
lichen planus is seen in approximately 10% of patients with skin lichen
planus. · LP
most commonly affects the proximal nail matrix and less frequently the nail
bed. · Nail
matrix lichen planus produces nail plate thinning, with longitudinal ridging
and splitting, onychoschizia, dorsal pterygium, and trachyonychia. · Nail
bed lichen planus causes onycholysis and mild subungual hyperkeratosis. · Several
nails are involved in most cases. Scarring of the nail matrix with dorsal
pterygium is a possible sequela. · Diagnosis
should be confirmed by nail biopsy, and systemic treatment is necessary to
avoid scarring. |
Introduction
Nail abnormalities are present in ~10% of
patients with disseminated lichen planus.
However, nail lichen planus is most frequently seen
in the absence of skin, scalp, or mucosal involvement. Several nails are
usually affected. Fingernails
are more frequently affected than toenails, with initial involvement of two or
three fingernails before subsequent involvement of the remaining digits. There are three major forms of nail LP: classic nail lichen planus, Trachyonychia (twenty-nail dystrophy) and Idiopathic atrophy of
the nails. Classic nail lichen planus is
common in adults, whereas the last two are common in children.
Clinical
features
The most common
changes of the classic LP are lateral thinning of the nail plate with lateral
loss, onychorrhexis (longitudinal ridging and fissuring of the nail plate with
brittleness and breakage) and onychoschizia (lamellar
exfoliation in which the distal nail plate splits horizontally into multiple
layers). These changes are manifestations of matrix damage and usually occur in the context of
severe generalized LP and the need for prompt treatment
to avoid scarring. In long standing disease, these different
features are associated with scarring signs (dorsal pterygium, atrophy,
anonychia) due to scarring of the nail matrix. Pterygium seemed to be
correlated with the duration of the disease, scarring rarely occurs in the
first year, while anonychia seemed to be independent.
Pterygium unguis is the most specific and unique nail
finding of lichen planus. It has been defined as wing shaped scar formation,
which is a result of severe nail matrix damage. If the entire length of the
nail matrix is involved in the inflammatory process, permanent destruction of
the nail matrix eventually gives rise to pterygium formation and permanent anonychia.
Pterygium unguis
also known as dorsal pterygiumis a
scarring process of the nail folds that extends into the matrix and nail bed. It is a wing-shapes scar and always irreversible,
consist of a gradual V shaped forward growth of skin of the proximal nail fold over the nail plate which
becomes splits because of the fusion of the proximal nail fold epidermis with
the underlying matrix and, subsequently, with the nail bed. As a result, the nail plate is divided into 2
lateral segments that progressively decrease in
size as the pterygium widens, leaving two small nail remnants. Complete
involvement of the matrix and the nail bed produces a total loss of the plate
and a permanent atrophy of the nail apparatus. It can affect finger and
toenails, the most commonly affected are the big toenails.
When differentiating nail lichen planus from other
diseases causing pterygium, simultaneous involvement of several digits is the
key point for the diagnosis, since in other diseases simultaneous involvement
is unexpected.
"Idiopathic atrophy of nails": Acute
progressive nail destruction leading to diffuse nail atrophy with and without
pterygium; complete loss of nail (anonychia).
LP of the nail
bed may give rise to longitudinal melanonychia, hyper pigmentation, subungual
hyperkeratosis and onycholysis. The tenting or pup-tent sign is
observed as a result of nail bed involvement that elevates the nail plate and
may cause longitudinal splitting. Onycholysis is quite frequent in both
fingernails and toenails. Severe toenail involvement causes features that
resemble yellow nail syndrome, with thickened, yellow–brown toenails. More
rarely, nail lichen planus may present with erosive lesions of the nail bed and
periungual tissues.
Treatment
Topical, intralesional, and systemic corticosteroids are
preferred treatments for nail lichen planus.
Nail matrix lichen planus requires oral or intramuscular
treatment with systemic steroids, which induce remission of the disease in 2/3
of the cases.
Systemic steroid is the treatment of choice: either oral
prednisone 0.5mg/kg or intramuscular triamcinolone acetonide
for cases manifesting significant compromise of function and causing debilating
pain.
Since systemic steroids are often necessary to halt the
disease process and preserve the existing nail; intralesional corticosteroid
matrix injections (triamcinolone 2.5 mg/cc in 1% lidocaine) are effective in
many patients with nail lichen planus affecting fewer than three digits. When
the injections are performed with ethyl chloride spray and talkesthesia
(distracting the patient using conversation) with a slow controlled technique,
the therapy is quite tolerable for patients, with the majority returning for
subsequent treatments.
Intramuscular corticosteroid injections (triamcinolone
0.5-1 mg/kg every 30 days for 5-7 months) have also been shown to have
excellent efficacy in treating nail lichen planus, in both the adult and
pediatric populations, and might decrease the risk for systemic side effects
compared with oral corticosteroids. However, with both oral and intramuscular
corticosteroids, relapse might occur after therapy in some patients.
Topical application of clobetasol propionate alone is
ineffective, except in mild cases, but may be combined with intramuscular and
intralesional injections.
In terms of prognosis, the response to treatment seems to be associated with
the initial severity of the NLP. Patients must be treated with systemic steroid
during 6 months, and a close follow-up during the first year is mandatory
because of high risk of relapse after the first treatment and initiate early
treatment.
Dorsal pterygium is not reversible and when it is the sole manifestation,
should not be treated.
‘TRACHYONYCHIA', ‘TWENTY NAIL DYSTROPHY', AND
‘SANDPAPER NAILS'
Introduction
Trachyonychia, also
known as twenty-nail dystrophy is a chronic
condition that can be idiopathic or associated with a variety of cutaneous and
systemic conditions characterized by diffuse
homogeneous roughness. Most cases are caused by atopic dermatitis, although
alopecia areata, psoriasis, and lichen planus are also found as the underlying
disorder. Children between 6-10 years of
age, sometimes younger, are commonly affected. The condition usually runs a
protracted course until, in many cases, the nails become normal from age of
14-16 years on.
Trachyonychia
is a sign of mild, diffuse damage to the proximal nail matrix by inflammatory
disorders.
Clinical features
Many nails, rarely all 20 nails, are
affected, but often 1 or more nails remain normal and the degree of severity
can vary from nail to nail. Two clinical varieties, opaque and shiny, are
described. In both forms, fingernails are affected more often than toenails.
In the more severe or opaque form,
the nails have a ‘sandpaper-like' appearance (the nails look like they have been
sandpapered in a longitudinal direction). These
nails present excessive longitudinal ridging due to fine superficial
striations distributed in a regular, parallel pattern. The nails become very rough, loose their shine and transparence, thin, and fragile with frequent onychoschizia. The cuticle
is hyperkeratotic, thickened and ragged.
In mild or shiny trachyonychia, the nails
retain their luster and are characterized by multiple small punctate
depressions distributed in a geometric pattern within parallel, longitudinal
lines. These reflect light and the nails
are not as thin and fragile as in opaque trachyonychia.
Differential diagnosis
Twenty-nail dystrophy differs from typical nail LP
because of its monomorphic appearance, i.e. the longitudinal ridging affects
the nail plate surface uniformly, and the absence of longitudinal splitting and
dorsal pterygium. Twenty-nail dystrophy is a benign condition that never
produces nail scarring.
Pathophysiology
The extent of inflammation in the
nail matrix is thought to contribute to the wide range of severity observed in
trachyonychia. When inflammation is severe and persistent, diffuse damage
causes an opaque variety. In contrast, mild and intermittent inflammation
results in multifocal damage, with nails that retain their luster as a result.
Trachyonychia is a clinical
diagnosis and there is no indication for a nail biopsy in these patients.
Trachyonychia never causes permanent nail damage or pterygium, including cases
of trachyonychia caused by lichen planus, and for this reason, there is no
necessity for a nail matrix punch or longitudinal nail biopsy, which is
invasive and can cause scarring. Pathological studies of trachyonychia showed
that the most common features are spongiosis and exocytosis of inflammatory
cells into the nail epithelia. Histopathology can also show the features of
nail matrix lichen planus or nail matrix psoriasis. Further, trachyonychia due
to nail lichen planus has been reported to occur in patients with alopecia areata,
suggesting that these two diseases can occur simultaneously.
Trachyonychia is a chronic
condition. However, it is important to keep in mind that it is neither scarring
nor painful, so treatment is often prescribed only for cosmetic reasons and
patients may often improve spontaneously without any treatment.
Conservative approaches include mild
emollients and camouflage with nail polish. An emollient may improve the nail
surface texture in opaque trachyonychia, while nail polish can help improve
appearance in shiny trachyonychia.
Topical options include corticosteroids,
tazarotene gel, and 5% 5-fluorouracil and calcipotriol/betamethasone
dipropionate ointment.
Procedure-based options reported in
the literature include nail plate dressings (ultra-thin adhesive bandage
applied once a week with lactic acid, silicon dioxide, aluminum
acetylacetonate, copolymer of vinyl acetate with acrylic acid, and azelaic
acid), intralesional injection of triamcinolone into the proximal nail fold,
and topical psoralen UVA. The once weekly nail plate dressings were found to
improve symptoms after 3 months in a pediatric patient. Intralesional
triamcinolone, while appearing efficacious, is uncomfortable and may not be an
appropriate selection for some pediatric patients.
Systemic treatments include biotin
2.5 mg/day, cyclosporine 2-3.5 mg/kg/day, retinoids, systemic corticosteroids and
tofacitinib citrate. In cases of trachyonychia due to psoriasis, acitretin is
an effective option. As treatment for trachyonychia is primarily for cosmetic
reasons, the decision to treat systemically should be made carefully in regard
to risk factors and patient preference.
IDIOPATHIC ATROPHY OF THE NAILS
Idiopathic atrophy of the nails is a rare variety of nail
matrix lichen planus characterized by abrupt onset and rapidly progressive painless
nail destruction leading to diffuse nail atrophy of several nails with absence
of the nail plate with and without pterygium.
Idiopathic atrophy of the nails is thus a distinct
variety of nail LP characterized by a very rapid and destructive evolution. The
opposite applies for LP presenting as 20-nail dystrophy, which should be
considered a very mild and benign form of NLP that does not produce scarring
and may regress spontaneously.
