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lichen planus

Wednesday 16 June 2004

WKP

Definition: Lichen planus is a papulosquamous disease. In its classical presentation, it is characterized by pruritic violaceous papules most commonly on the extremities of middle-aged adults. It may or may not be accompanied by oral and genital mucous membrane involvement. Its course is generally self-limited for a period of several months to years, but it may last indefinitely.

There are many clinical variants described, ranging from lichenoid drug eruptions to association with other diseases such as diabetes mellitus, autoimmune diseases, and the graft-versus-host reaction. The relationship of these, if any, to classical lichen planus is questionable. Multiple therapeutic options exist including corticosteroids, retinoids, griseofulvin, PUVA, and cyclosporine.

Lichen planus (LP) is a disease characterized by itchy reddish-purple polygon-shaped skin lesions on the lower back, wrists, and ankles. It may also present with a burning sensation in the mouth, and a lattice-like network of white lines near sites of erosion (Wickham striae).

The cause is unknown, but it is thought to be the result of an autoimmune process with an unknown initial trigger. There is no cure, but many different medications and procedures have been used in efforts to control the symptoms.

See also : lichenoid eruption

Microscopy

Lichen planus has thickened layers epidermis with apoptosis and Civatte bodies in the basal layer, sawtooth rete ridges, and a band of lymphocytes.

Lichen planus causes pruritic erythematous to purple papules on the skin, particularly the flexor surfaces, and the mucous membranes.

It is histologically characterized by: thickening of the epidermis - the stratum corneum (orthokeratosis on the skin, and parakeratosis in the oral form), the stratum granulosum, and the stratum spinosum (acanthosis). The stratum basale / basal layer shows areas of necrosis or apoptosis of the keratinocytes with the formation of Civatte bodies. A sawtooth pattern of the rete ridges is present, and a band of lymphocytes (mostly T cells) is present in the dermis deep to the basal layer. (On histology “lichenoid” refers to a band like inflammatory infiltrate).

Digital cases

- UI:902 - Lichen planus

Variants

- hypertrophic lichen planus (HLP)

Differential diagnosis

- lichenoid drug eruption
- lichenoid keratosis
- lichen striatus
- lichen niditus
- lichenoid purpura
- porokeratosis
- lichenoid actinic keratosis

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