Lichen planus is a common inflammatory skin disease that causes swelling and irritation on skin, nails, hair, and mouth. It is a cell-mediated immune reaction of unknown origin. Skin lesion of lichen planus causes an itchy rash inside the mouth, vagina, or mucosal area, it causes white patchy sores or burning sensation. It may be associated with immunosuppressive diseases, such as ulcerative colitis, vitiligo, alopecia areata, dermatomyositis, morphea, myasthenia gravis, and lichen sclerosus. In addition, a rare gene-related variant of lichen planus known as familial bullous lichen planus is also present.
What Are the Causes of Lichen Planus?
Lichen planus is an autoimmune disorder mediated by the immune T cell, in which these T-cells act against a protein in the skin and mucosa cells.
Contributing factors to lichen planus may include:
Physical and mental stress.
Lichen planus mostly appears as an isomorphic response after a skin injury or surgery (Koebnerization).
As an isotopic response to localized skin disease like herpes zoster.
Systemic viral infection like hepatitis C.
Contact allergy to chemicals or oral metal fillings (rare).
Certain drugs, graft-host responses after an organ transplant can cause a lichenoid eruption.
What Are the Types of Lichen Planus?
Lichen planus can be classified based on the histologic features as follows:
What Are the Symptoms of Lichen Planus?
The clinical presentation of lichen planus depends on the variant.
Cutaneous Lichen Planus:
The cutaneous variant is the classical lichen planus. Pinpoint to more than a centimeter, shiny plaque, and papules flat, hypertrophic, and firm on palpation. Plaques settle after a few months leaving a grayish-brown macule that fades after a year. Fine white lines crossing the plaque called Wickham striae is a characteristic feature. It may be scattered on the sun-exposed area like the neck, face, hands, wrists, lower back, and ankles. The color of the lesion varies according to the skin tone. Bullous and atrophic lichen planus are rare.
Oral Lichen Planus:
Oral lichen planus involves the sides of the tongue, inside of the cheeks, the gums, and lips. These are usually painless white stripes; painful, persistent erosions and ulcers as in erosive lichen planus; diffuse red gum flakes as desquamative gingivitis. It occurs as localized gum inflammation adjacent to amalgam fillings.
Vulval Lichen Planus:
Lichen planus affects labia majora and minora and vaginal introitus. Clinically it may be present as painless white streaks in a fern-like pattern or painful, persistent erosions and ulcers as in erosive lichen planus. Scarring may be present. Painful desquamative vaginitis produces a mucky vaginal discharge, and the eroded vagina bleeds easily.
Penile Lichen Planus:
Penile lichen planus presents as papules in a ring shape. White streaks and erosive lichen planus are less common.
Nail Lichen Planus:
Lichen planus of nails involves one or more nails, with or without affecting the skin's surface. When all the nails are involved, it is known as twenty-nail dystrophy. Lichen planus makes the nail plate thinner, creating grooves and ridges. The nail becomes dark, thick, or lifts the nail bed off the skin, a condition known as onycholysis. Sometimes the nail cuticle may be destroyed, forming a scar known as pterygium. The nails may fall off or stop growing, and they rarely disappear completely (anonychia).
Lichen Planus Pigmentosus:
Lichen planus pigmentosus is a diffuse oval, grayish-brown patch on the face, neck, trunk, and limbs. It is a form of acquired skin hyperpigmentation lesion. The leading cause is sun exposure. When lichen planus pigmentosus affects the lips, it results in patches of dark pigments on the upper and lower lips.
Lichen planopilaris are red papules commonly present on the smooth areas of the scalp. When the hair follicles get damaged, it can result in permanent baldness and sparse hairs. Frontal fibrosing alopecia, a variant of lichen planopilaris, affects the front portion of the scalp, forehead, and eyebrows.
Lichenoid Drug Eruption:
Lichenoid drug eruptions are lichen planus-like reactions that respond to certain medications. These are itchy or sometimes asymptomatic; pink, purple, or brown colored; flat, scaly patches commonly present on the trunk, oral mucosa, and other sites. Drugs that are commonly associated with lichenoid eruptions are Gold, Hydroxychloroquine, and Captopril. A photosensitive lichenoid drug eruption is seen after consuming Quinine and Thiazides.
Who Gets Lichen Planus?
Lichen planus involving the skin affects women and men equally over 40 years. 50 % of the lichen planus have oral manifestations and more commonly affect women than men. In addition, 10 % of lichen planus involves nails. Lichen planus is rare in younger or older people.
How Is Lichen Planus Diagnosed?
Lichen planus is mainly diagnosed with its clinical presentation. Along with it a few other diagnostic tests may be recommended which includes:
A biopsy may be recommended when suspecting cancer.
A direct immunofluorescent staining test is suggested.
A patch test may be performed in oral lichen planus patients to assess contact allergy.
What Is the Treatment for Lichen Planus?
Mostly lichen planus subsides within two years and does not require any treatment. However, treatment may be necessary when severe itching or sores are present in the mouth or genitals. In addition, lichen planus involving the scalp may cause permanent hair loss and should be intervened at the earliest. Lichen planus has no permanent cure, and the treatments aim to relieve the symptoms and promote healing.
Treatments options are:
Antihistaminic drugs - to relieve itching.
Topical or oral steroids - to fight inflammation depending on the severity of the lesion. Oral Prednisone along with Acitretin, Hydroxychloroquine, Methotrexate, Azathioprine, Mycophenolate mofetil is prescribed for the severe localized lesions.
Psoralen - ultraviolet light therapy.
Retinoic acid - a derivative of vitamin A.
Topical Tacrolimus and Pimecrolimus are used for eczema.
Pioglitazone has shown to improve the lichen planopilaris.
In oral lichen planus due to metal filling, replacing the metal filling with tooth-colored filling resolves the lesion.
What Are the Complications of Lichen Planus?
Oral sores make it difficult to eat.
Oral lichen planus can be an early sign of oral cancer.
Vulva and vaginal lichen planus cause severe pain and leave scars. In such cases, sexual dysfunction can develop as a long-term complication.
Lichen planus involving the ear canal may cause hearing loss when left untreated.
Rarely, long-lasting erosive lichen planus of mouth, vulva, or penis results in true squamous cell carcinoma of the region involved. Cancer from other variants of lichen planus is uncommon.
How to Prevent Lichen Planus?
There is no preventive measure that can completely prevent the lesion. But once the lesion occurs, measures only help prevent it from worsening.
Avoid skin injuries.
Give cold compression.
In the case of oral lichen planus, avoid smoking and alcohol, maintain good oral hygiene, and avoid foods that irritate the mouth.
Lichen planus usually subsides on its own. However, it may recur in some patients.
What Is the Prognosis for Lichen Planus?
Cutaneous lichen planus have an excellent prognosis as they tend to clear within a few years.
Mucosal lichen planus have a good prognosis and persists for more than a decade.
Lichenoid drug eruptions usually show a good prognosis when the liable medication is withdrawn.
Lichen planus is the most commonly occurring skin and mucosal lesion. Lichen planus is not contagious. Most mild lichen planus cases can be treated with at-home therapy without medical treatments. However, medical intervention is required if the condition becomes severe, causing pain or itching.