Lichen planus

Clinic

• LP is a chronic inflammatory and immune-mediated disease that affects the skin, nails, hair, and mucous membranes.
• It is characterized by polygonal, flat-topped, violaceous papules and plaques with overlying, reticulated, fine white scale (Wickham's striae)
• LP commonly affecting dorsal hands, flexural wrists and forearms, trunk, anterior lower legs and oral mucosa. The hue may be gray-brown in people with darker skin. Although there is a broad clinical range of LP manifestations, the skin and oral cavity remain as the major sites of involvement.

Classification[edit]

Lichen planus lesions are so called because of their "lichen-like" appearance and can be classified by the site they involve, or by their morphology.

Site

LP may be categorized as affecting mucosal or cutaneous surfaces.

• Cutaneous forms are those affecting the skin, scalp, and nails.
• Mucosal forms are those affecting the lining of the gastrointestinal tract (mouth, pharynx, esophagus, stomach, anus), larynx, and other mucosal surfaces including the genitals, peritoneum, ears, nose, bladder and conjunctiva of the eyes.

Pattern

Lichen planus lesions can occur in many different forms:

Lesion morphology	Description
Papular	Papular form is the classic cutaneous lichen planus (CLP) lesion characterized by shiny, red or purple-colored, flat-topped papule. Lesions may have a thin, transparent, and adherent scale. Fine whitish points or lacy lines (Wickham's striae) may be seen on the surface of well-developed papules.
Annular	'Ring-shaped' lesions that develop gradually from single small pigmented spots into circular groups of papules with clear, unaffected skin in the center. The ring-like lesions may very slowly enlarge, co-join and morph into larger irregular (serpentine) bands, sometimes accompanied by lines (See Linear, below). Annular CLP is uncommon and classically involves the male genitalia (glans penis and penile shaft), groin, axilla and also the extremities.
Linear	Papules are arranged in a line (the "Blaschko line"). This pattern may develop secondary to trauma (koebnerization) or, uncommonly, as a spontaneous, isolated eruption, usually on the extremities, and rarely on the face.
Hypertrophic	This pattern is characterized by hyperkeratotic thick pruritic red-brown to purple-gray plaques with follicular accentuation. Hypertrophic CLP commonly involves the extremities, especially the interphalangeal joints and the anterior legs in a symmetrical distribution. This form is also known as "lichen planus verrucosus".
Atrophic	This morphology is characterized by the presence of a few well-demarcated, white-bluish papules or plaques with central superficial atrophy. Atrophic CLP is the clinical endpoint of chronic annular or hypertrophic LP with atrophic lesions. The use of potent topical corticosteroids for a long-term may predispose the patient to developing atrophic lesions.
Bullous	This morphology is characterized by the development of vesicles and bullae with the skin lesions. This is a rare variant of lichen planus, and also known as "vesiculobullous lichen planus."
Actinic	Rare form presenting as nummular patches or plaques with a hypopigmented halo surrounding a hyperpigmented center. Actinic CLP is more prevalent in African Americans, Indians, and Middle-Eastern individuals and commonly affects the sun-exposed areas.
Ulcerative	This morphology is characterized by chronic, painful bullae and ulceration of the feet, often with cicatricial sequelae evident. This is a rare variant of lichen planus.
Pigmented	This morphology is characterized by hyperpigmented, dark-brown macules in sun-exposed areas and flexural folds. This is a rare variant of lichen planus.
Follicular	Characterized by follicular, flat, elevated or hemispherical erythematous papules with or without keratoses presenting in groups or disseminated. The Graham‐Little‐Piccardi‐Lasseur syndrome, seen in a familial pattern and also predominantly in women, is characterized by the appearance of follicular LP on the trunk with LP follicularis decalvans on the scalp. Follicular LP on the scalp is more likely to lead to scarring alopecia.
Inverse	Characterized by extensive erythematous lesions with poorly defined borders and in part with lichenification. Inverse LP typically affects the axillae, inguinal creases, limb flexures and submammary region. Pigmentation of the individual lesions at these inverse locations are typical. Additionally, keratotic papules and erosions with a bizarre configuration can occur.

Overlap syndromes

Occasionally, lichen planus is known to occur with other conditions. For example:

• Lupus erythematosus overlap syndrome. Lesions of this syndrome share features of both lupus erythematosus and lichen planus. Lesions are usually large and hypopigmented, atrophic, and with a red to blue colour and minimal scaling. Telangectasia may be present.
• Lichen sclerosus overlap syndrome, sharing features of lichen planus and lichen sclerosus.

Signs and symptoms

Although lichen planus can present with a variety of lesions, the most common presentation is as a well defined area of purple-coloured, itchy, flat-topped papules with interspersed lacy white lines (Wickham's striae). This description is known as the characteristic "6 Ps" of lichen planus: planar (flat-topped), purple, polygonal, pruritic, papules, and plaques. This rash, after regressing, is likely to leave an area of hyperpigmentation that slowly fades. That said, a variety of other lesions can also occur.

Skin[edit]

Cutaneous lichen planus on the shin Lichen planus involving the nails

Variants of cutaneous lichen planus are distinguished based upon the appearance of the lesions and/or their distribution. Lesions can affect the:

• Extremities (face, dorsal hands, arms, and nape of neck). This is more common in Middle Eastern countries in spring and summer, where sunlight appears to have a precipitating effect.
• Palms and soles
• Intertriginous areas of the skin. This is also known as "inverse lichen planus."
• Nails characterized by irregular longitudinal grooving and ridging of the nail plate, thinning of the nail plate, pterygium formation, shedding of the nail plate with atrophy of the nail bed, subungual keratosis, longitudinal erthronychia (red streaks), and subungual hyperpigmentation. A sand-papered appearance is present in around 10% of individuals with nail lichen planus.
• Hair and scalp. The scalp is rarely affected by a condition known as lichen planopilaris, acuminatus, follicular lichen planus, and peripilaris, characterised by violaceous, adherent follicular scale with progressive scarring alopecia. While lichen planus and lichen planopilaris may occur together, aside from sharing the term 'lichen' and revealing inflammation on skin biopsy, there is neither established data on their co-occurrence nor data to suggest a common etiology. Lichen planopilaris is considered an orphan disease with no definitive prevalence data and no proven effective treatments.

Other variants may include:

• Lichen planus pemphigoides characterized by the development of tense blisters atop lesions of lichen planus or the development vesicles de novo on uninvolved skin.
• Keratosis lichenoides chronica (also known as "Nekam's disease") is a rare dermatosis characterized by violaceous papular and nodular lesions, often arranged in a linear or reticulate pattern on the dorsal hands and feet, extremities, and buttock, and some cases manifest by seborrheic dermatitis-like eruption on the scalp and face; also palmo plantar keratosis has been reported.
• Lichenoid keratoses (also known as "benign lichenoid keratosis," and "Solitary lichen planus") is a cutaneous condition characterized by brown to red scaling maculopapules, found on sun-exposed skin of extremities. Restated, this is a cutaneous condition usually characterized by a solitary dusky-red to violaceous papular skin lesion.
• Lichenoid dermatitis represents a wide range of cutaneous disorders characterized by lichen planus-like skin lesions.

Mucous membranes[edit]

Lichen planus on the lips and the lateral border of the tongue Lichen planus affecting mucosal surfaces may have one lesion or be multifocal. Examples of lichen planus affecting mucosal surfaces include:

• Esophageal lichen planus, affecting the esophageal mucosa. This can present with difficulty or pain when swallowing due to oesophageal inflammation, or as the development of an esophageal stricture. It has also been hypothesized that it is a precursor to squamous cell carcinoma of the esophagus.
• Genital lichen planus, which may cause lesions on the glans penis or skin of the scrotum in males, and the vulva or vagina in females. Symptoms may include lower urinary tract symptoms associated with stenosis of the urethra, painful sexual intercourse, and itching. In females, Vulvovaginal-gingival syndrome, is severe and distinct variant affecting the vulva, vagina, and gums, with complications including scarring, vaginal stricture formation, or vulva destruction. The corresponding syndrome in males, affecting the glans penis and gums, is the peno-gingival syndrome. It is associated with HLA-DQB1.

Mouth[edit]

Classic white striations of non-erosive lichen planus in the left buccal mucosa (left cheek) Oral lichen planus (also termed oral mucosal lichen planus), is a form of mucosal lichen planus, where lichen planus involves the oral mucosa, the lining of the mouth. This may occur in combination with other variants of lichen planus. Six clinical forms of oral lichen planus (OLP) are recognized:

Lesion morphology	Description
Reticular	The most common presentation of oral lichen planus (OLP), is characterised by the net-like or spider web-like appearance of lacy white lines, oral variants of Wickham's straiae. This is usually asymptomatic. Reticular OLP may eventually progress to the more severe subtypes such as the erosive form.
Erosive/ Ulcerative	The second most common form and the most advance form of oral lichen planus, is characterised by oral ulcers presenting with persistent, irregular areas of redness, ulcerations and erosions covered with a yellow slough. This can occur in one or more areas of the mouth. In 25% of people with erosive oral lichen planus, the gums are involved, described as desquamative gingivitis (a condition not unique to lichen planus). This may be the initial or only sign of the condition. Involvement of the dorsum of the tongue might cause an altered sense of taste (dysgeusia).
Papular	This form is characterized by small white pinpoint papules that are asymptomatic. Hence, they can be easily missed during a routine checkup. It is referred to as the initial and transient phase of OLP.
Plaque-like	Large, homogenous white patches are characteristic of this form which may resemble leukoplakia. This form is more prevalent in tobacco smokers.
Atrophic	This form is a common presentation that has similarities to the erosive form. It has a more prominent atrophic lesion on a background of erythema with radiating white striae at the margins. Atrophic oral lichen planus may also manifest as desquamative gingivitis.
Bullous	Rare form of OLP characterized by fluid-filled vesicles ranging in size from 1 to 2 mm to several cm in diameter. The vesicles or bullae appear white or gray-purple in color and are fluctuant. The fluid in the vesicles are usually clear but may be hemorrhagic or purulent upon secondary infection. These rupture easily and they leave an ulcerated, painful surface.[citation needed]

These types often coexist in the same individual. Oral lichen planus (OLP) tends to present bilaterally as mostly white lesions on the inner cheek, although any mucosal site in the mouth may be involved. Other sites, in decreasing order of frequency, may include the tongue, lips, gingivae, floor of the mouth, and very rarely, the palate.

Generally, oral lichen planus tends not to cause any discomfort or pain, although some people may experience soreness when eating or drinking acidic or spicy foodstuffs or beverages. When symptoms arise, they are most commonly associated with the atrophic and ulcerative subtypes. These symptoms can include a burning sensation to severe pain. They may also experience mucosal bleeding in response to mild trauma, such as toothbrushing. Additionally, the Koebner phenomenon (the development of new lesions at sites of trauma) is not only present in cutaneous lichen planus (CLP) but can also occur in the setting of OLP.

Residual postinflammatory hyperpigmentation has been reported in association with OLP, manifesting as brown to black pigmentation on the oral mucosa and may most likely occur in dark-skinned individuals.

OLP may occur as a sole manifestation of the disease or in conjunction with other clinical manifestations of LP, including cutaneous LP, genital LP, nail LP, and lichen planopilaris (scalp LP).

Causes

• Immune-mediated mechanism

• Hypersensitivity reaction
• Viral infection

Miasm

HCV