10 Lichen Planus
Lichen planus (LP) is a disease that has great variation in onset, appearance, and course. This section will present only the common features and usual course.
CLINICAL APPLICATION QUESTIONS
A 41-year-old woman presents with a slowly evolving intensely pruritic papular skin eruption over both volar forearms and pretibial areas. This is of 3 months’ duration. She also complains of a painful erosion on the right buccal mucosa, a chronic pruritic scaling eruption on the soles of both feet, and intermittent irritated erosions on the outer vulva that interfere with intercourse.
1. Which, if any, of the above lesions may be lichen planus?
2. If any of these lesions are not lichen planus, what are they?
3. If you are uncertain of the diagnosis of lichen planus on clinical findings alone, how can you confirm the diagnosis?
4. What are the causes of lichen planus?
5. How should this patient be treated?
6. What is the prognosis for lichen planus?
APPLICATION GUIDELINES Specific History
Onset
LP is very uncommon in children and occurs most often in adults in their fourth, fifth, and sixth decades. Family clusters are occasionally seen. Most cases begin insidiously with the onset of intensely pruritic red to deeply violet-colored papules that gradually increase in number and extent until the patient is sufficiently symptomatic to seek relief.
A small number of cases present with a dramatic generalized exanthematic onset. These patients are immensely uncomfortable and socially devastated. Occasionally, painful oral lesions predominate. Uncommon nail, follicular, and ulcerating variants will not be dis- cussed in this chapter.
Evolution of Disease Process
A small number of cases will resolve spontaneously within a few weeks. Ninety percent of cases will resolve by 24 months. About 10% of patients will develop chronic LP, usually in the form of oral mucous membrane lesions or hypertrophic lesions on the lower limbs. Occasionally, patients present with recurrent episodes that are separated by
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From: Current Clinical Practice: Dermatology Skills for Primary Care: An Illustrated Guide D.J. Trozak, D.J. Tennenhouse, and J.J. Russell © Humana Press, Totowa, NJ
symptom-free periods. Some patients have only a small number of lesions in a very lim- ited area, while others have hundreds of lesions over much of the body surface. Almost all complain of intense itch that is disproportionate to the visible rash.
Evolution of Skin Lesions
LP begins with tiny papules that retain the skin marking lines and are therefore geo- metric or polygonal in shape. When first seen they are usually 3 to 5 mm in size and are palpably raised. Individual lesions can enlarge up to 1 cm. When lesions are grouped, they can merge to form tight aggregates of considerable size. They may then evolve into plaques or their papular origin may remain evident.
Provoking Factors
Some cases of LP are precipitated by a chronic tinea pedis and will resolve and recur with the activity of the fungal infection. Like psoriasis, LP will activate at sites of trauma and therefore shows a true Koebner phenomenon. In this disease, however, trauma induc- tion is an incidental sign that supports the diagnosis but does not contribute in any signif- icant way to the extent of the disease. A wide range of medications produce LP-like drug eruptions; however, it is uncertain at present whether these represent a separate entity or unmasking of idiopathic LP.
Self-Medication
Self-treatment is not a problem in LP, except where a covert medication might cause an LP-like drug eruption.
Supplemental Review From General History
A careful medication history is essential, and any medication reported to cause an LP- like eruption should be discontinued. The features of these drug eruptions are sometimes strikingly similar to the idiopathic disease both clinically and microscopically, and offend- ing drugs will be uncovered only by careful history. The list of medications that cause these reactions continues to grow and any agent should be suspect. These drug-induced eruptions are slow to clear and it is not unusual for improvement to take 2 or 3 months.
LP has also been associated with an increased incidence of autoimmune diseases (Sjögren’s syndrome, sicca syndrome, alopecia areata, vitiligo, ulcerative colitis, myas- thenia gravis, and diabetes mellitus), chronic dermatophyte infections, and chronic liver disease (primary biliary cirrhosis, alcoholic cirrhosis, chronic active hepatitis B and C).
The presence of a fungal infection is usually significant: the authors have seen many cases of LP that clear and exacerbate with its activity. LP-like lesions are seen in patients with graft-versus-host reactions.
Dermatologic Physical Exam Primary Lesions
Primary LP lesions are red to deep violet, flat-topped, angular geometric (polygonal) 1- to 3-mm papules. The papules may be separate or tightly grouped (see Photo 31).
Wickham’s stria are a lacy network of white lines seen on the surface of the papules considered pathognomonic for LP (see Photo 32).
Early lesions tend to be red to dusky deep red. As the papules mature they acquire a deep violaceous hue, which is considered typical. As pigment is dropped from the basal cell layer some lesions may also have a brown cast.
Secondary Lesions
1. Scale is adherent and white, but not a prominent feature except in some hyper- trophic variants (see Photo 33).
2. Large plaques form from coalescing papules, and the original papular morphol- ogy may be obscured. Satellite papules are frequently present at the periphery as a clue (see Photo 34).
3. Erosions are common with mucosal LP and occur on occasion in chronic hyper- trophic lesions (see Photos 32,35,36).
4. Scarring and atrophy are common with LP of the hair-bearing scalp, the nail matrix, and chronic hypertrophic lesions. Permanent hair and nail loss can occur, sometimes rapidly (see Photo 37).
5. Although victims complain bitterly of itching, excoriations are seldom seen in LP.
6. Dense purple or deep brown hyperpigmentation can occur as lesions resolve. This pigmentary change may last for years.
Distribution
Microdistribution: Follicular distribution is encountered on rare occasions. The dis- ease may attack any hair bearing area. Follicular LP may be seen with other typical skin and mucous membrane lesions or may occur alone. It presents as pin-head-sized conical, rough red papules pierced by a hair. Permanent hair loss may occur.
Macrodistribution: The oral cavity shows a lacy white reticulated or arborizing pat- tern, most commonly on the posterior buccal mucosa opposite the molars. It will not rub off with a tongue blade. Oral lesions occur in 30 to 70% of cases depending on the series.
Rare cases occur with oral, genital, and anal involvement only.
Classic papular lesions have a predilection for flexural surfaces of joints and forearms.
Other frequent sites are the dorsal hands, extensor shins, lateral neck, buttocks, sacrum, glans penis, and ankles (see Fig. 9). The face, scalp, palms, and soles are only rarely involved.
In the exanthematic form, lesions can be distributed uniformly over much of the body surface and the characteristic distribution pattern is lost. The morphology of the primary lesions is usually diagnostic and oral lesions are found in a high proportion of cases as a supporting feature.
Configuration
1. Grouped papules are the most common pattern. If the grouping is follicular rather than random, the papules are small and evenly spaced following the anatomic spacing of the follicles.
2. Annular (ring) lesions with central clearing or central atrophy may occur but are uncommon. These are most often located on the glans penis.
3. Linear (long narrow band) lesions occur very rarely.
4. Reticulated (net-like or arborizing) configuration may occur with oral lesions.
Indicated Supporting Diagnostic Data
In many instances, oral and cutaneous lichen planus are clinically diagnostic and no specific laboratory testing is indicated.
Skin Biopsy
This test is indicated when the disease is strongly suspected but the diagnosis is clin- ically uncertain. Although LP and LP-like drug eruptions may show identical histology, subtle differences can sometimes point toward the latter diagnosis. Biopsy is particularly helpful for differentiating lichen planus and lupus erythematosus.
Direct Immunofluorescence
Although rarely needed, this test can be helpful in supporting a diagnosis of LP where other parameters are confusing. The pattern is quite different from that of lupus erythe- matosus; however, it is identical in an LP-like drug eruption.
Figure 9: Macrodistribution of lichen planus.
General Laboratory Testing
The strong association of LP with chronic liver disease and hepatitis in some European series has led some authors to recommend routine screening. This association has not been confirmed in North America, and at present it would seem prudent to coor- dinate additional testing with information revealed in the review from the general history.
Therapy
Because LP is generally a self-limiting disorder, the aim should be to provide the patient with as much comfort as is possible with minimal risk. It must be kept in mind that the pruritus of limited disease can be very distressing, and eruptive LP is socially humili- ating. Whenever possible, try to limit treatment to topical or intralesional regimens. When disease is extensive, this is not always possible and there is a point where systemic ther- apy is needed.
Topical Therapy
Limited LP will respond to topical steroids but effective treatment usually requires the most potent topical that is safe in a given skin region (carefully review the section in Chapter 4 on topical steroids). Resistant areas will often respond to a combination of a steroid cream alternated with topical tretinoin cream in the highest concentration toler- ated. The prescribing practitioner should pay careful attention to surface area and total amount of topical steroid in use. If either of these is excessive, systemic treatment should be considered rather than trying to accomplish the same effect with an uncontrolled topi- cal treatment.
Hypertrophic LP may respond to topical corticoids, but is less steroid-sensitive than other inflammatory skin conditions and often requires a group I steroid in an optimized vehicle. An alternative is to use a weaker product with plastic wrap occlusion. This method, which was developed prior to the arrival of the superpotent steroids, has a higher incidence of side effects and often leads to patient compliance problems.
Oral LP often responds well to a regimen of topical 0.05% fluocinonide ointment administered three to four times during the day. This agent is poorly absorbed from the bowel and systemic absorption has not been a problem. At bedtime, topical tretinoin cream is applied starting with the highest strength tolerated. Consider starting with the 0.05% cream and switching to the 0.1% concentration as the membrane responds.
Tacrolimus ointment 0.1% has also proved quite effective in the treatment of oral LP. This immune modulator avoids the cutaneous atrophy associated with topical steroids but is fairly new and unique side effects may not yet be fully appreciated. Keep in mind that per- sisting ulceration of oral LP may signal a rare conversion to squamous cell carcinoma and a timely referral to a dermatologic consultant may be life-saving.
Intralesional Therapy
Intralesional therapy is useful for resistant localized LP and hypertrophic LP. Consider starting at a concentration of 2.5 mg/cc of triamcinolone acetonide diluted in physiologic saline. Often 5- or even 10-mg/cc concentrations are needed with thick hypertrophic areas.
More concentrated solutions limit the area that can be safely treated without risk of sys- temic effects. The total monthly dose should always be recorded and monitored. On occa- sion, this technique may be useful with resistant oral lesions.
Systemic Therapy
Generalized disease that is too extensive for safe or effective topical treatment, and nail or scalp involvement that can leave disfiguring scarring, are indications for systemic therapy. If the practitioner is unsure of the situation, prompt referral to a dermatologist is then indicated. Among the multitude of systemic agents which have been reported effec- tive, the following drugs are worth consideration.
Griseofulvin: Several years ago, this antifungal agent was reported in a controlled study to clear a high proportion of cases. Although subsequent studies have been con- flicting, it is an agent with a very reasonable side-effect profile and is well worth consid- eration in the treatment of widespread nonscarring LP or LP with a concomitant dermatophyte infection. In the latter situation, it is the initial drug of choice. When grise- ofulvin is effective, some improvement is seen within 30 days. This is usually evident as decreased pruritus, flattening of the papules, and a cessation of new lesions. Because of its slow onset and spotty efficacy, it should not be used for rapidly advancing exanthematic LP or where significant scarring can occur. With adults, consider starting with a dose of 1 g/day of ultramicronized griseofulvin divided into four equal doses. Administration at the start of a meal, or with milk enhances absorption and minimizes GI side effects. A baseline CBC should be obtained, as well as liver chemistries if there is any suggestion of prior liver disease. The drug is continued until clearing is complete. With prolonged use, a CBC and liver panel are recommended on a 3-month schedule. Much has been said about griseofulvin causing LP-like drug eruptions. This has been a rare event but should be kept in mind in the face of worsening disease.
Systemic steroids: In cases of rapidly advancing exanthematic LP, or when scarring scalp or nail lesions are present, systemic steroids are justified. In adult cases, prednisone in a single morning dose of 30 to 40 mg/day should be initiated then rapidly tapered once control is achieved. Often small areas of resistant disease persist that require topical treat- ment while the systemic agent is withdrawn. A practitioner using systemic corticoids must be fully aware of the side effects, contraindications, and monitoring required for safe usage.
Other agents: Systemic retinoid therapy, dapsone, and antimalarial agents have each been reported helpful in treating special problem types of LP. As these treatments are out- side of standard therapy, such cases should be referred to a dermatological consultant.
Conditions That May Simulate Lichen Planus LP-Like Drug Eruptions
These have been reported with a large number of medications. Thiazide diuretics, gold, antimalarials,β-blocking agents, vitamins, and NSAIDs are among those most com- monly cited. This differential must be carefully evaluated in every case of LP. Some reac- tions are clinically identical to idiopathic LP; however, subtle findings on routine biopsy may help to distinguish them. Immunopathology is not helpful. LP-like drug reactions resolve slowly and require a good deal of support and confidence on the part of the treat- ing practitioner. Clinical features that help to distinguish the two include a photodistribu- tion and a psoriasis-like appearance common with the drug-induced form.
Lupus Erythematosus
Rarely cases are encountered where these two disorders seem to merge. In most instances, a biopsy combined with direct immunofluorescence will distinguish between them. Most cases turn out to be chronic discoid lupus. Rare overlap cases do occur.
Secondary Syphilis
Exanthematic LP without pruritus may be difficult to separate from a generalized papu- losquamous syphilid. The latter is associated with lymphadenopathy and constitutional symptoms. A syphilis serology with precautions regarding prozone effect is definitive.
ANSWERS TO CLINICAL APPLICATION QUESTIONS History Review
A 41-year-old woman presents with a slowly evolving intensely pruritic papular skin eruption over both volar forearms and pretibial areas. This is of 3 months’ duration. She also complains of a painful erosion on the right buccal mucosa, a chronic pruritic scaling eruption on the soles of both feet, and intermittent irritated erosions on the outer vulva that interfere with intercourse.
1. Which, if any, of the above lesions may be lichen planus?
Answer: The papular skin eruption over both volar forearms and pretibial areas is a classic distribution of lichen planus. Erosive mucous membrane lesions are also a common feature of lichen planus
2. If any of these lesions are not lichen planus, what are they?
Answer: The chronic pruritic scaling eruption on the soles of both feet is not lichen planus but is typical of tinea pedis, which can be linked etiologically to lichen planus.
3. If you are uncertain of the diagnosis of lichen planus on clinical findings alone, how can you confirm the diagnosis?
Answer: Lichen planus has a characteristic histology on biopsy.
4. What are the causes of lichen planus?
Answer: Most cases of lichen planus are idiopathic. A significant number are drug-induced (thiazide diuretics, NSAIDs,β-blocking agents, etc.) or linked to chronic dermatophyte infections. Linkage to autoimmune disease and chronic liver disease is established but uncommon.
5. How should this patient be treated?
Answer: After the presence of an active tinea pedis is confirmed by KOH prepa- ration, initial treatment should consist of systemic treatment for the tinea pedis. In many instances, the lichen planus will remit when the fungal infection is eradi- cated. If drug-induced lichen planus is suspected, elimination of the suspect med- ication is the first measure. In idiopathic lichen planus, treatment may range from
topical steroids to systemic retinoids, depending on the stage and extent of the disease.
6. What is the prognosis for lichen planus?
Answer: Idiopathic lichen planus usually remits spontaneously in 12 to 24 months. Recurrences are common and chronic persistent cases do occur. Mucous membrane lichen planus has a much greater tendency to be chronic and unremit- ting. Drug-induced lichen planus and dermatophyte-associated cases usually remain clear once the offending drug is withdrawn or the dermatophyte infection is adequately treated.
