Lichen planus (LP) is a persistent disease characterised by an abnormal immune system reaction causing flat bumps or plaques to appear on the body. It commonly affects the skin, the scalp, the nails, and the mucous membranes. The mucous membranes affected by LP include internal surfaces of the gastrointestinal tract (oral cavity, pharynx, oesophagus, anus, and stomach), larynx, genital areas, nose, ears, bladder, inner layer of eyes and lining of the abdominal cavity. The exact aetiology (cause) of LP is unknown, however we know that it is non-infectious.1 The disease is more prevalent in people assigned female at birth (AFAB) than those assigned male at birth (AMAB), and most commonly occurs in those aged 30 to 60 years. This condition can, in some cases, lead to cancer of the lip, tongue, oral cavity, oesophagus, vulva, and larynx.2
Causes of lichen planus
The exact cause of LP is unknown.1 There are a few probable causes of LP suggested in the scientific literature :
- Autoimmune response - LP is believed to develop due to an inflammatory autoimmune response. External factors like drugs, viruses, or contact allergens cause a change in the epidermal self-antigens and the body’s immune system attacks its own cells and tissue1
- Genetic causes - genetic factors might also aggravate the risk of LP in some patients
- Drug reactions - drugs like antimalarial agents, quinidine, beta-blockers, penicillamine, thiazide diuretics, non-steroidal anti-inflammatory drugs (NSAIDs e.g. ibuprofen), angiotensin-converting enzyme (ACE) inhibitors, and tumour necrosis factor (TNF)-alpha inhibitors are all related to incidence of LP1
- Dental materials and metal infections - oral LP is closely correlated with contact allergies to a group of metals and substances used widely in dental restoratives and toothpaste; those materials cause contact hypersensitivity and may lead to the development of oral LP. When the sensitivity metal is taken away, LP lesions usually clear up2,3
- Viral invasion - hepatitis C virus (HCV) is also a probable causative factor of oral LP3
- Stress - various studies have shown that people suffering from anxiety and depression are often reported to develop oral LP3
- Diabetes and hypertension - some studies described a relationship between oral LP and diabetes mellitus as well as vascular hypertension.4 The classic triad of oral LP, diabetes mellitus, and vascular hypertension is called Grinspan’s syndrome3
- Habits - certain bad habits like betel nut chewing and cigarette smoking are believed to be a major cause of oral LP4
Signs and symptoms of lichen planus
Lichen planus is characterised by itchy skin and mucous membrane lesions that might be localised or generalised (spread throughout the body). The typical characteristics of those lesions are known as ‘The Six P’s of LP’: purple, planar, polygonal, pruritic, papules, and plaques, a few millimetres dimensionally.1
- The lesions are firm on palpation, shiny and covered by whitish lines or bands called the Wickham striae
- They most commonly occur on the wrist flexors, the backside of hands, ankles, and the front part of the lower legs
- Pruritus (itching) is one of the most unpleasant symptoms of LP and may be mild or severe
- Bullous LP - transparent, yellow, fluid-filled vesicles/bullae on the legs, can be small or large in size
- Lichen planus pemphigoid's - blisters on top of existing LP lesions or on unaffected skin
- Hypertrophic LP - yellow-grey, red, and reddish-brown plaques and papules on the front of the legs and ankles
- Ulcerative LP - painful erosive lesions on the bottom of the foot, resulting in problems with movement or walking
- Lichen planus pigmentosus - macular or papular pigmented lesions arranged in patterns (Blaschkoid, follicular, or linear)
- Extensive erythematous lesions - lesions characterised by not having definite borders, seen in armpits, limb flexures, below breast region, and inguinal creases1
- A half of LP patients suffer from mucosal lesions, which are the most prevalent in the mouth. Other sites are the oesophagus, the lips, the glans penis and the vulva, or the vagina
- The erosive and atrophic LP types are frequently accompanied by a burning pain and spicy or hot foods might worsen it1
- The most prevalent type is the reticular LP, found bilaterally on the buccal mucosa (inner cheeks), the tongue, the lips, the floor of the mouth, the gums, and the palate4
- People AFAB are more commonly affected by oesophageal LP - lesions that can lead to dysphagia, an abnormal narrowing of the oesophageal lumen, and further to squamous cell carcinoma1
These lesions emerge in an annular pattern over the glans penis. In females, erosive LP is more common and includes lesions on the vulva or vagina and might progress to more difficult conditions like scarring and strictures (narrowing of the vagina). LP affecting female genitalia and the gums is called vulvovaginal-gingival syndrome.1
LP affecting nails commonly causes thinning of the nail plate and longitudinal ridging. It is more predominant in children.1
Lichenoid drug eruption
Lichenoid drug eruptions, also known as drug-induced LP, occur as an adverse effect of some medications.
Management and treatment for lichen planus
There is no remedy for lichen planus, but the symptoms such as itching, inflammation, and rash can be alleviated through medications and other medical advancements. The lesion might take several months and up to 2-3 years to resorb completely, but in some cases, they may never fully heal; if the condition is mild, no treatment is required.
Treatment options include:
- Topical corticosteroids - to reduce inflammation and relieve itching; examples include clobetasol, betamethasone, and triamcinolone
- Intralesional steroid injections - for example, with triamcinolone1
- Oral corticosteroids - administered in severe cases, e.g. prednisone might help with painful mouth ulcers
- Immune modulators - medication is given to suppress your immune system and the autoimmune reaction
- Antihistamines - to help mitigate itching
- Retinoids - topical retinoids (vitamin A derivatives), in cream or gel forms, are used to help normalise cell growth and reduce inflammation
- Calcineurin inhibitors - to suppress the immune system and reduce inflammation1
- Light treatment - e.g. PUVA (psoralen plus ultraviolet A ) is recommended in severe cases of LP
- Laser treatment - useful in treating brown spots left on skin after LP heals
- Cryotherapy and surgical excision - used in some severe cases of oral LP4
- Removal of trigger- removal of any drugs or allergens that may be causing LP
- Good oral hygiene - regularly brushing and flossing your teeth, as well as attending dental check ups is important for managing LP and preventing secondary infection
The diagnosis of lichen planus includes a combination of an assessment of your medical history and a careful observation of symptoms.
- Medical history - a complete medical history should be discussed along with detailed information about the onset, duration, and progression of symptoms
- The classic six P’s (purple, planar, polygonal, pruritic, papules, and plaques) should be looked out for when observing the lesions. The medications used by the patient between a few weeks to months prior to first symptoms should also be discussed
- Biopsy - a biopsy (taking a small skin sample from the patient) can be done to confirm LP in the affected area if examining the lesions doesn’t provide enough confidence in the diagnosis
- Blood tests - your blood might be tested for conditions related to LP such as a hepatitis C infection
LP can occur at any age, mostly in middle-aged adults but it most commonly occurs in people AFAB. At a higher risk of LP are those with hepatitis C infection and high levels of stress or anxiety. Some drugs can also cause LP such as antimalarial agents, quinidine, beta-blockers, penicillamine, thiazide diuretics or non-steroidal anti-inflammatory drugs (NSAIDs).
- Patients with erosive LP can develop secondary infections like candidiasis or herpes simplex
- In penile and vulval LP patients, squamous cell carcinoma can develop
- Scarring can cause difficulty in eating, swallowing, sexual intercourse, and urination1
How can I prevent lichen planus?
Since the exact cause of LP is unknown, there aren’t any researched ways in which the condition can be prevented. It is advised to avoid identified trigger agents like allergens or excessive psychological stress. Good personal and oral hygiene should also be maintained. Regular appointments with healthcare professionals for checkups are also a good practice and so is the treatment of hepatitis C infections, if present.
How common is lichen planus?
While LP of the skin is less common and occurs in approximately 0.2 to 1% of adults, oral LP is more prevalent and affects 1 to 4% of adults worldwide.1
Is lichen planus contagious?
No, it is not. It's neither transmitted by skin contact nor sexually.
What can I expect if I have lichen planus?
LP may or may not require treatment, depending on the severity of the lesions. It usually takes several months and up to 5 years to clear. However, in some rare cases, the condition never subsides. Problems in swallowing and during intercourse can occur, but appropriate treatment can reduce those difficulties.
When should I see a doctor?
You should see a doctor if you notice small, pruritic (itchy) bumps or rash on your skin, mouth, scalp, nails, or genitalia and difficulty in swallowing, eating, or painful sexual intercourse due to an unknown reason, lasting for a longer interval of time.4
LP is a chronic autoimmune condition. Its exact cause is still unclear. It is an inflammatory disorder of the skin and mucous membranes which can be described as itchy, purple, painful papules or plaques with distinctive white lines, occuring on the wrists, ankles, and lower back region. It can also cause painful sores in the mouth and other mucosal areas. Triggers may include stress, medication, infections, or allergens. Treatment involves managing symptoms and reducing inflammation with topical or oral corticosteroids, light therapy, Laser, and surgical excision depending on the severity of the disorder. LP can pass on its own but regular monitoring and follow-up with a healthcare professional is crucial.
- Arnold DL, Krishnamurthy K. Lichen Planus. [Updated 2023 Jun 1]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan. Available from: https://www.ncbi.nlm.nih.gov/books/NBK526126/
- Halonen P, Jakobsson M, Heikinheimo O, Riska A, Gissler M, Pukkala E. Cancer risk of Lichen planus: A cohort study of 13,100 women in Finland. Int J Cancer. 2018 Jan; 142: 18-22. Available from: https://onlinelibrary.wiley.com/doi/full/10.1002/ijc.31025
- Shafer AW, Hine MK, Levy BM, Oral I, B Sivapathasundharam. Shafer’s textbook of oral pathology. New Delhi: Elsevier, A Division Of Reed Elsevier India Private Limited; 2015.
- Gupta S, Jawanda MK. Oral lichen planus: An update on etiology, pathogenesis, clinical presentation, diagnosis and management. Indian J Dermatol. 2015 May-Jun; 60(3):222-9. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4458931/