Purple, pruritic papules on the inner wrist.
Purple, pruritic papules on the inner wrist.
Lichen planus (LP) is a chronic inflammatory condition that can affect the skin, mouth, nails, and genitals, causing itchy, purple, flat-topped papules and plaques, sometimes with lacy white patches in the mouth.
Itchy, violaceous to purple papules and plaques are typical. The surface often has a characteristic white, lacy pattern, called Wickham's stria. As individual lesions heal, residual pigmentation in the form of post inflammatory hyperpigmentation is common. Koebnerization may occur and pruritus may be intense. The inner wrists, ankles, sides of feet, back, oral mucosa, vulva and penis are favored sites. However, the entire body may be covered in severe cases. Thickened, hypertrophic lesions are more common on the legs. A variant of LP in the sun-exposed areas is called lichen planus actinicus. Milia may develop. Rarely bulla may form. The nails may become dystrophic. Very rarely, lesions may occasionally be scaly, putting them in the papulosquamous differential.
An ever-growing number of drugs have been noted to cause lichen planus-like eruptions. These include the new biologics, antimalarials, arsenicals, beta blockers, captopril, furosemide, gold salts, methyl dopa, penicillamine quinidine, sulfonylurea, salsalate and thiazides. One patient's LP was caused by gold-containing cinnamon schnapps. There is some variation in nomenclature. Do these drugs induce lichen planus or do they cause a lichenoid drug eruption? This site has chosen to use the term lichenoid drug eruption.
Because of the association with liver disease, screening labs (e.g. Hepatitis B and C, SGPT) should be obtained. In a recent meta study, LP was significantly associated with an increased risk of dyslipidemia and higher triglyceride levels [Int J Dermatol. 2016 Feb 12].
In a recent study of treatment patterns by dermatologists, 53% of patients went untreated. The most commonly prescribed treatments were topical corticosteroids (38.3%), followed by systemic steroids (9%), intralesional corticosteroids (4.4%), and topical calcineurin inhibitors (4.3%). [JAAD April 2025]
Classic lichen planus often clears spontaneously in approximately 1 year (although chronic and treatment-resistant cases do occur). Often the therapeutic approach is to shorten the time to resolution and relieving pruritus, with topical corticosteroids as first-line therapy. For limited disease, a potent topical steroid should be tried along with the admonition not to scratch. A steroid-impregnated tape changed daily (e.g. Cordran) may also help. Alternatively, IL kenalog, e.g. 5-10 mg/cc given monthly may help the patient with limited disease.
For extensive disease, nb-UVB is an excellent approach with minimal side effects and is considered first line therapy. However the newer JAK inhibitors should be considered.
Prednisone 40-60 mg/day may be given. The patient should be made aware of its potential side effects. The steroid may be tapered over 1-3 months but recurrences are common. Alternatively, IM triamcinolone 40-60 mg once a month for several months may be effective. Also, pulse therapy may be used. .
Topical ruxolitinib BID was highly effective in the treatment lichen planus. [J Invest Dermatol 2022 Aug;142(8):2109]
Great response to JAK-1 inhibitor upadacitinib AAD 2024.
Other therapies that have been employed include hydroxychloroquine, methotrexate, cyclosporin, and acitretin.
Post-inflammatory hyperpigmentation is common with LP>
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