What You Should Know About Lichen Planus
Lichen planus can be a challenging condition to diagnose. Accordingly, these authors review variations of lichen planus, offer insights on the differential diagnosis and essential treatment tips. Lichen planus (LP), one of the so-called “papulosquamous diseases,” is a form of dermatitis which produces a characteristic skin lesion that is classically papular in configuration. This very distinctive eruption is often described with six Ps: pruritic, polygonal, planar, purple, papules and plaques. Individual lesions of lichen planus classically possess a fine scaly surface that exhibits lacey white striations, aptly called “Wickham’s striae,” or small gray or white pinpoint spots or puncta. Such lesions range from very discrete, individual lesions of 1 to 3 mm in diameter to larger, coalesced lesions of 4 to 5 mm in diameter. Cutaneous lichen planus may involve the wrist and forearms, lumbar area, penis, anterior aspect of the lower legs, ankles, dorsum of the hands and feet, and acral surfaces. Oral lesions occur in approximately one-third of patients with lichen planus and nail involvement occurs in about 10 percent of reported cases. The majority of nail changes result from damage to the nail matrix, usually involving only one or two fingernails or toenails, but occasionally all nails are affected. Nail changes associated with lichen planus include longitudinal ridging and grooving, splitting, nail thinning and nail loss. In severe cases, the nail may be temporarily or permanently destroyed with prominent pterygium formation. Lesions on the palms and soles are less common but do occur. In such acral locations, the morphologic expressions of lichen planus are more widely varied than in alternate locations. In many instances, lichen planus of the acral surfaces will have features in common with hypertrophic lichen planus. One will see the formation of large yellow hyperkeratotic papules or plaques rather than the small purple papules clinicians would see with the classic form of lichen planus. Unlike lichen planus arising in alternate locations, pruritus might not be a prominent feature on acral surfaces. In other words, the lesions usually do not itch, are not polygonal and do not have the lacey Wickham’s striae. There may be more familiar-appearing lesions of lichen planus that are adjacent to the lesions on the acral surfaces. As a general rule, palmoplantar presentations are exceedingly difficult to diagnose. These presentations require close inspection in hopes of finding more typical appearing lesions on non-acral skin. Men and women are equally affected. Men are most often affected by lichen planus between the ages of 20 and 60. In women, the incidence increases with advancing age. While cases of lichen planus have been reported in young children, the condition is generally considered rare in this age group. The precise cause of lichen planus is essentially unknown, although, many studies have demonstrated that the immunologic system is a central player in the pathogenesis of the condition. Lymphocytes, particularly CD8-positive T-cells, appear to act within involved skin to potentiate the clinical manifestations if not cause them outright. While most cases of lichen planus appear to be idiopathic, some are linked to medications or hepatitis C virus (HCV) infection. Medications may include oral gold, antimalarial agents, penicillamine, thiazide diuretics, beta blockers, nonsteroidal antiinflammatory drugs (NSAIDs), quinidine and angiotensin converting enzyme inhibitors. Familial cases may arise but are extremely uncommon.
A Guide To The Variant Forms Of Lichen Planus
There are several clinical variants of lichen planus including hypertrophic, acral, atrophic, follicular, annular, vesicular and bullous, and actinic lichen planus. Hypertrophic lichen planus. These extremely pruritic lesions most often occur on the extensor surfaces of the lower extremity, the ankles and along the medial aspect of the foot. The surface of the lesions often feels rough and raised, and appears “warty.” This sometimes leads to a misdiagnosis of mosaic verrucae. Hypertrophic lesions are often chronic and heavily pigmented. They are also more difficult to treat as they often leave residual pigmentation and scarring of the affected skin, even after the lesions are cleared. While one can expect the majority of cases of non-acral and non-hypertrophic lichen planus to resolve within two years, this is not the case with hypertrophic lichen planus, which may be persist for decades. Acral lichen planus. This expression of lichen planus is worth distinguishing due to its unusual morphologic presentations, recalcitrance to conventional therapy, and role as a diagnostic pitfall for clinicians who deal with lower extremity skin conditions. As its name implies, acral lichen planus affects the non-hair-bearing skin of the plantar and palmar surfaces, and may be darkly pigmented. Some patients may have more classically appearing lesions on the dorsum of the foot or in distal sites but this is not a requisite for the diagnosis. Individual lesions often consist of yellow and hyperkeratotic papules, and plaques, some of which may be focally erosive. Isolated involvement of single digits resulting in an enlarged purpuric toe, with or without nail involvement, might occur. Bizarre manifestations such as diffuse keratoderma are unique to cases of lichen planus that arise in acral locations. Atrophic lichen planus. This form is characterized by a few lesions, which often represent once classic active lesions of lichen planus begin to resolve. In these cases, one will see the typical elevated polygonal violaceous lesion turn into a lesion which has an upper layer scaling crust and appears to be “melting” into the surrounding epidermis. This is frequently misdiagnosed as psoriasis. The atrophic form of lichen planus often appears during cortisone treatment of existing lichen planus, especially on the lower extremities. Follicular lichen planus. Lichen planopilaris usually occurs alone but may occur in association with more typical forms of lichen planus. This variant exhibits epithelial changes that are identical to those of classic lichen planus. However, rather than involving the surface epidermis, follicular lichen planus affects only the epithelium of the hair follicles. The hair follicles on any hair-covered area may be affected, particularly on the scalp and on the lower extremity. Since only the hair follicles are involved, the clinical lesions are much smaller than the classic form and display a “folliculocentric” distribution. Around the affected follicles, clinicians may notice acuminate (sharp-pointed), keratotic papules that may also exhibit scaling and atrophy. Active lesions may result in temporary alopecia. Scarring and permanent hair loss sometimes results in chronic cases. Annular lichen planus. These lesions form an annular pattern with a ring of small confluent papules with central clearing and peripheral spreading. One may see these in addition to the typical pattern of lichen planus, particularly on the lower legs. One variety occurs with only a few large, scattered, annular lesions that may involve the legs or feet. When these lesions are present, without any usual patterned lichen planus, one may not recognize the eruption clinically but the dermatopathology remains characteristic. The most common misdiagnosis of annular lichen planus is that of tinea corporis. Vesicular and bullous lichen planus. Vesicular lichen planus is likely simply a precursor or subtype of bullous lichen planus. This is a very distinct and common variant of lichen planus that occurs as small red to violaceous vesicles that are moderately pruritic. These lesions may appear in direct relation to past or present patches of lichen planus, or they may be the primary presenting lesions. At times, large bullae may form, especially on the dorsum and sides of the feet. Frequently, the vesicles or bullae are broken due to rubbing, pressure or scratching. This leaves a deep erosion or superficial ulcer that will heal slowly. Several cases of vesicular lichen planus have been reported that involve the arms and legs, or the feet only. Actinic lichen planus. These mildly pruritic lesions occur on sun-exposed areas and on sunburned skin, and may be pigmented, dyschromic or similar in appearance to granuloma annulare and follicular lichen planus but without the associated hairs. This actinic reaction is primarily due to Koebner’s phenomenon, in which ultraviolet light irradiation has aggravated an existing disease. The scalp and nails are usually not affected in this condition. There is also a variety that seems to be a separate entity that occurs in Middle Eastern and Mediterranean countries, and involves the light-exposed areas of the skin in children and young adults.
Keys To The Differential Diagnosis
The differential diagnosis of lichen planus includes several spongiotic and alternate papulosquamous dermatoses such as chronic eczematous or chronic allergic contact dermatitis, psoriasis, lichen simplex chronicus, lichen niditus, pityriasis rosea, pityriasis rubra pilaris, tinea and warts. On acral surfaces, one should foremost consider psoriasis, palmoplantar keratoderma, chronic eczematous dermatitis and tinea pedis. It may not be possible to clinically differentiate nail involvement by lichen planus from involvement by psoriasis, primary onychomycosis or traumatic nail unit dystrophy. One could reach a diagnosis of lichen planus on the basis of the typical clinical appearance and a punch biopsy of a representative lesion. However, it cannot be overemphasized that lichen planus involving the lower legs and feet may not have the classical clinical appearance described in most textbooks. Histopathology reveals characteristic findings of a band-like infiltrate of lymphocytes at the epidermal-dermal junction and damage to the basal cell layer. Epidermal changes include irregular psoriasiform hyperplasia with a “saw-tooth” appearance. In addition, there is accentuation of the granular layer of the epidermis that assumes a wedge shape. The epidermis shows irregular psoriasiform hyperplasia in a saw-toothed appearance.
What Are Effective Treatment Options?
One must tailor the treatment of lichen planus to the individual patient presentation. Patients vary greatly when it comes to the severity of symptoms, extent of lesion involvement and response to treatment. Cases of non-acral and non-hypertrophic lichen planus tend to regress after varying amounts of time with 40 to 60 percent of patients showing spontaneous clearance within one year. For this reason, in classic cases of lichen planus, one should treat only the patient’s symptoms. Topical wet dressings reduce the pruritus and decrease the inflammatory nature of individual lesions. Wet dressings may also augment other topical treatments. For acute lichen planus, the importance of reviewing the patient’s drug history cannot be over-emphasized. The removal of the offending drugs or chemicals may be necessary to control the reaction. In addition, new onset lichen planus in people at risk for hepatitis B or hepatitis C exposure should prompt serologic testing for associated antigens and antibodies. Using this important clue, we have been tipped off to the presence of undiagnosed hepatitis C in a young woman. For the most part, lichen planus is a corticosteroid responsive disorder and, for the majority of patients, only topical corticosteroids are needed. However, in mild cases, particularly those that arise in younger patients, one might consider symptomatic therapy using a trial of oral antihistamines, topical antipruritics and soothing baths as first-line therapy. In continuing cases or moderately symptomatic cases, one may use topical fluorinated corticosteroid compounds. In severe or more acute cases, a tapered course of oral corticosteroids may be required for two to four weeks, using prednisone 10 to 40 mg daily. As mentioned earlier, one may see an interesting phenomenon of “melting” during the early stages of oral corticosteroid therapy. This condition is one in which the elevated lesions appear to become flatter, lighter in color and spread into the adjacent tissue planes, eventually responding to the topical therapy. In chronic, nonresponsive generalized lichen planus, intermittent megadose corticosteroid therapy may be warranted. Sometimes, topical fluorinated corticosteroids (flurandrenolide) with polyethylene occlusive dressing (Cordran tape) may be very beneficial, particularly on the lower legs and feet. Clinicians may also inject individual lesions with small amounts of dexamethasone phosphate mixed with equal amounts of a local anesthetic agent. Other lesions such as hypertrophic LP and nail lesions may also benefit from intralesional injections of 10 mg/ml of triamcinolone acetonide. Flattening of the lesions should occur after one or two injections. Monitor these high-potency corticosteroids closely and use them for only a short time to prevent cortisone complications. Cases of lichen planus that are recalcitrant despite appropriate corticosteroid therapy may respond to combined corticosteroids and topical 1% pimecrolimus (Elidel, Novartis). Unfortunately, in many instances, both acral and hypertrophic variants of LP will prove recalcitrant to topical corticosteroid and non-steroidal therapy alone. In such cases, the standard of care dictates oral retinoids as second-line therapy. Some authorities have advocated the use of oral retinoids as a first-line therapeutic approach for the treatment of extensive or severely symptomatic cases of lichen planus. Commonly prescribed retinoids for use in this context are isotretinoin (Accutane, Roche Pharmaceuticals) 10 mg po bid for two months or acitretin (Soriatane, Stiefel) 30 mg po qd. Such products are not indicated for women during childbearing years without first ruling out the possibility of pregnancy and eliminating the possibility of pregnancy during the course of therapy. Since these products may induce hyperlipidemia in some people, a pre-therapeutic lipid profile and liver function tests are suggested. In many instances, clinicians may use oral retinoids in addition to low-dose oral corticosteroids. The antiinflammatory properties of the latter add further benefit in the treatment of lichen planus, and may have the added benefit of limiting mucocutaneous irritation sometimes associated with retinoid use. Cases that remain recalcitrant to therapy require third-line therapies, the most common of which is cyclosporine or PUVA (photochemotherapy). Finally, a very important part of the management of lichen planus is rest and relaxation. Patients frequently show significant improvement of their skin condition when their emotional status changes or when they are otherwise removed from stressful environments. Significant improvements have occurred in people who embark on stress-free vacations. The prognosis of lichen planus is good as most cases regress within 18 months or are responsive to conservative corticosteroid therapy. As the lesions heal, there may be residual pigmentary changes but these stains may eventually fade with time without further treatment. Only about one out of five people with resolved cases of classic lichen planus will have a second attack of lichen planus. Again, patients with acral or hypertrophic variants of lichen planus (both are most common in the lower extremity) may have a significantly worse battle with this potentially disabling disease. A large proportion of such cases will prove recalcitrant to first-line therapeutic modalities and many will not fully respond to second-line approaches. Unlike other variants, these conditions often remain active for extended periods of time, becoming chronic conditions that persist for years or decades.
Lichen planus is an inflammatory mucocutaneous condition with characteristic violaceous polygonal flat-topped papules and plaques. Pruritus is often very severe. Cutaneous lesions may occasionally be disfiguring and involvement of the skin, oral mucosa or genital mucosa may all occur. Cases limited to the skin of the acral surfaces may occur and such cases may exhibit a wide array of clinical manifestations. While most cases of lichen planus are idiopathic, some may be caused by the ingestion of certain medications or be linked to hepatitis C or hepatitis B virus infections. When it comes to patients with localized lichen planus, clinicians usually can provide successful treatment with potent topical corticosteroids while systemic steroids may be necessary in the treatment of patients with generalized lichen planus. In regard to acral and hypertrophic variants, it is not uncommon for these conditions to require the added use of oral retinoids for successful management. Dr. Dockery is a Fellow of the American College of Foot and Ankle Surgeons, the American College of Foot and Ankle Pediatrics, and the American Society of Podiatric Dermatology. He is board certified in foot and ankle surgery. Dr. Dockery is the Chairman of the Board and Director of Scientific Affairs for the Northwest Podiatric Foundation for Education & Research, USA. Dr. Dockery is the author of Cutaneous Disorders of the Lower Extremity (Saunders, 1997) and Lower Extremity Soft Tissue & Cutaneous Plastic Surgery (Elsevier Sciences, 2006). Dr. Bakotic is the Director of the Institute for Podiatric Pathology in Pompano Beach, Fla. He is a Fellow of the American Board of Pathology and the American Board of Dermatology.
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