A 32-year-old woman presents with a 3-week history of an itchy rash covering her whole body. Physical examination reveals papules that are distributed on the trunk and extremities, including on both wrists. The patient states that the rash is intensely itchy. On closer examination of the papules, a white scale with a reticulated pattern is noted over the purple papules.
Submit your diagnosis to see full explanation.
Lichen planus is an inflammatory disorder in which papules develop on the skin. The papules are characterized by purple color, polygonal shape, and pruritic nature. They often have white striations called Wickham striae. Lichen planus most often occurs in those age 30 to 50 years, with dermatoses developing in men earlier than in women.1 The papules are often distributed throughout the body but may be especially numerous around the wrists, arms, and legs, where skin is exposed to frequent bending and unbending.1 Most cases of lichen planus are idiopathic, although some cases may be caused by minor trauma to the skin (Koebner phenomenon) or by oral medications, including common drugs such as beta-blockers, thiazide diuretics, and nonsteroidal anti-inflammatory drugs.2
Lichen planus is classified based on the site, configuration, and morphology of the papules. The cutaneous form of lichen planus is found on the skin, scalp, or nails, and the mucosal form of lichen planus is found on mucosal surfaces such as the mouth or genital mucosa.2 The configuration of lichen planus lesions may be annular (a ring of papules around normal tissue) or linear.3 The morphology of lichen planus lesions may be hypertrophic (thickened and hyperkeratotic), atrophic (white-bluish papules with clear borders), vesiculobullous (papules accompanied with vesicles and bullae), or erosive (papules accompanied with erosions, ulcers, and granulation tissue).1
A diagnosis of lichen planus is typically made based on the appearance of the dermatoses. This is often summarized by the four Ps: purple, polygonal, pruritic, and papule. However, histopathology analysis following punch biopsy can be used to confirm the diagnosis.1 Histopathology of lichen planus includes the appearance of lymphocytes in the dermis and necrotic keratinocytes in the epidermis.4
Treatment for cutaneous lichen planus includes mid- to high-potency topical steroids such as triamcinolone or clobetasol (for localized lichen planus) and oral corticosteroids such as prednisone (for generalized cutaneous lichen planus), sometimes in conjunction with psoralen and ultraviolet A treatment.3 Retinoids such as acitretin and immunosuppressive agents such as cyclosporine are also options for the treatment of generalized cutaneous lichen planus.1
Strategies for treating mucosal lichen planus are similar to those for treating cutaneous lichen planus, including treatments such as topical steroids for mild cases and systemic steroids for severe cases.1 Topical or oral retinoids can also be used in cases of steroid resistance; however, the rate of recurrence for mucosal lichen planus is high following cessation of treatment.2
It should be noted that not all cases of lichen planus can be treated using a single method because cases of lichen planus vary greatly in their site, configuration, and morphology. In addition, not all cases of lichen planus should be treated because some cases may cause only mild discomfort, whereas others may result in disability resulting from intense pruritus.1
Young Moon, BS, is a student and Maura Holcomb, MD, is a dermatology resident at Baylor College of Medicine in Houston.
- Goldsmith L, Katz S, Gilchrest B, et al. Fitzpatrick’s Dermatology in General Medicine. 8th ed. New York, NY: McGraw Hill Education; 2012.
- Katta R. Lichen planus. Am Fam Physician.2000;61(11):3319-3324.
- Boyd AS, Neldner KH. Lichen planus. J Am Acad Dermatol. 1991;25(4):593-619.
- Elder DE, Elenitsas R, Johnson BL, Murphy GF, Xu X, eds.Lever’s Histopathology of the Skin. 10th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2009.