Lichen Planus Clinical Presentation

Most cases of lichen planus (LP) are insidious.

• The initial lichen planus lesion is usually located on the flexor surface of the limbs, such as the wrists (see the image below). After a week or more, a generalized eruption develops with maximal spreading within 2-16 weeks. Lichen planus on the flexor part of the wrist.
• Pruritus is common in lichen planus but varies in severity depending on the type of lesion and the extent of involvement. Hypertrophic lesions are extremely pruritic.
• Oral lesions may be asymptomatic or have a burning sensation, or they may even be painful if erosions are present.
• In more than 50% of patients with cutaneous disease, the lesions resolve within 6 months, and 85% of cases subside within 18 months. On the other hand, oral lichen planus had been reported to have a mean duration of 5 years. Large, annular, hypertrophic lesions and mucous membrane involvement are more likely to become chronic.

In addition to the cutaneous eruption, lichen planus (LP) can involve the mucous membranes, the genitalia, the nails, and the scalp. The clinical presentation of lichen planus has several forms: actinic, annular, atrophic, erosive, follicular, hypertrophic, linear, pigmented, and vesicular/bullous. The papules are violaceous, shiny, and polygonal; varying in size from 1 mm to greater than 1 cm in diameter (see the image below). They can be discrete or arranged in groups of lines or circles. Characteristic fine, white lines, called Wickham stria, are often found on the papules (see the image below).

Mucous membrane involvement is common and may be found without skin involvement. Lesions are most commonly found on the tongue and the buccal mucosa; they are characterized by white or gray streaks forming a linear or reticular pattern on a violaceous background (see the image below). Oral lesions are classified as reticular, plaquelike, atrophic, papular, erosive, and bullous. Ulcerated oral lesions may have a higher incidence of malignant transformation in men, but this observation may be confounded by other factors, such as smoking and chewing tobacco. Lesions may also be found on the conjunctivae, the larynx, the esophagus, the tonsils, the bladder, the vulva, and the vaginal vault; throughout the gastrointestinal tract; and around the anus.

Genital involvement is common in men with cutaneous lichen planus. Typically, an annular configuration of papules is seen on the glans. Less commonly, linear white striae, similar to the lesions on the vulva and the vagina, can be seen on male genitalia. Vulvar involvement can range from reticulate papules to severe erosions. Dyspareunia, a burning sensation, and pruritus are common. Vulvar and urethral stenosis can also be present. Two reports documented that more than 50% women with oral lichen planus had undiagnosed vulvar lichen planus.^{[10, 11]} Also see the clinical guideline summary, Diagnosis and management of vulvar skin disorders.^[12]

In 10% of lichen planus patients, ungual findings are present. Most commonly, nail plate thinning causes longitudinal grooving and ridging. Hyperpigmentation, subungual hyperkeratosis, onycholysis, and longitudinal melanonychia can result from lichen planus. Rarely, the matrix can be permanently destroyed with prominent pterygium formation. Lichen planus has been linked to childhood idiopathic nail atrophy and may overlap with twenty-nail dystrophy of childhood.

Lichen planus patients with a cutaneous eruption may also have follicular and perifollicular violaceous, scaly, pruritic papules on the scalp. These lesions can progress to atrophic cicatricial alopecia that can appear many weeks after the skin lesions have disappeared. Pseudopelade can be a final endpoint.

Variations in lichen planus include the following:

• Hypertrophic lichen planus: These extremely pruritic lesions are most often found on the extensor surfaces of the lower extremities, especially around the ankles. Hypertrophic lesions are often chronic; residual pigmentation and scarring can occur when the lesions eventually clear.
• Atrophic lichen planus: Atrophic lichen planus is characterized by a few lesions, which are often the resolution of annular or hypertrophic lesions.
• Erosive/ulcerative lichen planus: These lesions are found on the mucosal surfaces and evolve from sites of previous lichen planus involvement.
• Follicular lichen planus: Lichen planopilaris is characterized by keratotic papules that may coalesce into plaques. This condition is more common in women than in men, and ungual and erosive mucosal involvement is more likely to be present. A scarring alopecia may result.
• Annular lichen planus: Lichen planus papules that are purely annular are rare. Annular lesions with an atrophic center can be found on the buccal mucosa and the male genitalia.
• Linear lichen planus: Isolated linear lesions may form a zosteriform lesion, or they may develop as a Köbner effect.
• Vesicular and bullous lichen planus: Most commonly, these lesions develop on the lower limbs or in the mouth from preexisting lichen planus lesions. A rare condition, lichen planus pemphigoides, is a combination of both lichen planus and bullous pemphigoid.
• Actinic lichen planus: Subtropic or actinic lichen planus occurs in regions, such as Africa, the Middle East, and India. This mildly pruritic eruption usually spares the nails, the scalp, the mucous membranes, and covered areas. Lesions are characterized by nummular patches with a hypopigmented zone surrounding a hyperpigmented center.
• Lichen planus pigmentosus: This is a rare variant of lichen planus but can be more common in persons with darker-pigmented skin, such as Latinos or Asians. It usually appears on face and neck. Some believe it is similar to or the same as erythema dyschromicum perstans (ie, ashy dermatosis).
• Lichen planus pemphigoides: This is a rare form of lichen planus. Blisters subsequently develop on lichen planus lesions. Clinically, histopathologically and immunopathologically, it has features of lichen planus and bullous pemphigoid, it but carries a better prognosis than pemphigoid.

The exact cause of lichen planus (LP) is not known. The pathogenesis of lichen planus is immunologically mediated. Whether the foreign antigen is a virus or a drug is not known. Langerhans cells process antigens, which are then presented to T lymphocytes. This stimulated lymphocytic infiltrate is epidermotropic and attacks keratinocytes. During this lymphocytotoxic process, the keratinocytes release cytokines that attract more lymphocytes. This process has been referred to as the lichenoid tissue reaction. In addition, recent studies reveal a disruption in the epithelial anchoring system.

Some patients with lichen planus have a positive family history. It has been noted that affected families have an increased frequency of human leukocyte antigen B7 (HLA-B7). Others have found an association between idiopathic lichen planus and human leukocyte antigen DR1 (HLA-DR1) and human leukocyte antigen DR10 (HLA-DR10); thus, lichen planus may be influenced by a genetic predisposition.