Lichen Planus

Introduction | Aetiology and Risk Factors | Clinical Presentation | Diagnosis | Management and Treatment | When to Refer | References

Introduction

Lichen planus is a chronic inflammatory skin condition that can affect the skin, mucous membranes, nails, and hair. It is characterised by purplish, flat-topped papules and plaques, often accompanied by intense itching. Lichen planus is considered an autoimmune condition, where the body's immune system attacks the skin and mucous membranes. While the exact cause is unknown, it is thought to involve a combination of genetic predisposition, environmental factors, and immune system dysfunction.

Aetiology and Risk Factors

The exact cause of lichen planus is not fully understood, but several factors are thought to contribute to its development:

• Autoimmune Response: Lichen planus is believed to be an autoimmune condition where T cells attack the basal layer of the epidermis and mucosal surfaces.
• Genetic Predisposition: A family history of lichen planus or other autoimmune conditions may increase the risk.
• Infections: Hepatitis C virus infection has been associated with lichen planus, particularly oral lichen planus.
• Medications: Certain medications, such as non-steroidal anti-inflammatory drugs (NSAIDs), beta-blockers, and antimalarials, can trigger a lichenoid drug reaction, which mimics lichen planus.
• Stress: Psychological stress may exacerbate or trigger the condition.
• Allergens: Contact with certain allergens, such as dental materials (e.g., amalgam fillings), may contribute to oral lichen planus.

Clinical Presentation

Lichen planus can present in various forms, affecting different parts of the body:

1. Cutaneous Lichen Planus

• Violaceous Papules: The hallmark of cutaneous lichen planus is flat-topped, purplish (violaceous) papules and plaques, typically 2-10 mm in diameter.
• Wickham’s Striae: Fine, white, lacy lines known as Wickham’s striae may be visible on the surface of the papules, especially when examined under magnification.
• Distribution: Lesions are commonly found on the flexor surfaces of the wrists, forearms, ankles, and lower back, but they can occur anywhere on the body.
• Itching: Intense pruritus is a common symptom, which can lead to scratching and secondary excoriations.

2. Oral Lichen Planus

• White Lacy Patches: Oral lichen planus presents as white, lacy patches or streaks on the buccal mucosa, tongue, and gums. These may be asymptomatic or cause burning and discomfort.
• Erosive Lesions: In more severe cases, erosive or ulcerative lesions may develop, leading to significant pain and difficulty eating.

3. Genital Lichen Planus

• Lesions: Lichen planus can affect the genital mucosa, presenting as white or erythematous patches, erosions, or plaques. In women, it often affects the vulva and can be associated with vaginal involvement.
• Symptoms: Genital lichen planus may cause itching, pain, and discomfort, particularly during sexual activity.

4. Nail Lichen Planus

• Nail Changes: Lichen planus can affect the nails, leading to thinning, ridging, splitting, and, in severe cases, complete nail loss (anonychia).

5. Scalp Lichen Planus (Lichen Planopilaris)

• Scarring Alopecia: Lichen planus can affect the scalp, causing patchy hair loss due to scarring (cicatricial alopecia). This is known as lichen planopilaris.

Diagnosis

The diagnosis of lichen planus is primarily clinical, based on the characteristic appearance of the lesions and patient history:

• History: Take a detailed history, including the onset and progression of symptoms, potential triggers (e.g., medications, infections), and any family history of autoimmune conditions.
• Physical Examination: Examine the skin, mucous membranes, nails, and scalp for the characteristic features of lichen planus, such as violaceous papules, Wickham’s striae, and erosive lesions.
• Dermatoscopy: Dermatoscopy may help in visualising Wickham’s striae and distinguishing lichen planus from other dermatological conditions.
• Skin Biopsy: A skin biopsy is often performed to confirm the diagnosis. Histopathological findings include hyperkeratosis, saw-tooth rete ridges, and a band-like lymphocytic infiltrate at the dermoepidermal junction.
• Blood Tests: Hepatitis C serology may be performed, particularly in patients with oral lichen planus, to rule out an underlying hepatitis C infection.

Management and Treatment

Management of lichen planus involves symptom relief, reducing inflammation, and monitoring for potential complications. Treatment is tailored to the severity and location of the lesions:

1. Topical Treatments

• Topical Corticosteroids: Potent topical corticosteroids (e.g., clobetasol propionate) are the first-line treatment for cutaneous lichen planus. They reduce inflammation and itching. For oral lesions, corticosteroid mouthwashes or orabase preparations may be used.
• Topical Calcineurin Inhibitors: Tacrolimus or pimecrolimus can be used as steroid-sparing agents, particularly for oral and genital lichen planus where prolonged steroid use may be problematic.
• Topical Retinoids: Topical retinoids (e.g., tretinoin) may be used in some cases, particularly for hypertrophic lichen planus, to help normalise keratinisation.

2. Oral Treatments

• Oral Corticosteroids: For severe or widespread lichen planus, a short course of oral corticosteroids may be required to control the inflammation.
• Oral Retinoids: Acitretin, an oral retinoid, may be used for severe cases of cutaneous lichen planus, particularly when other treatments have failed.
• Immunosuppressants: Medications such as methotrexate, cyclosporine, or azathioprine may be considered for refractory cases or when systemic corticosteroids are contraindicated.

3. Phototherapy

• PUVA Therapy: Photochemotherapy with psoralen and ultraviolet A (PUVA) can be effective for widespread cutaneous lichen planus, helping to reduce inflammation and control symptoms.
• Narrowband UVB Therapy: An alternative to PUVA, narrowband UVB therapy is less invasive and may be used for less severe cases.

4. Lifestyle and Supportive Care

• Oral Hygiene: For oral lichen planus, maintaining good oral hygiene is crucial. Avoiding triggers such as spicy foods, alcohol, and tobacco can help reduce symptoms.
• Stress Management: Stress reduction techniques such as mindfulness, relaxation exercises, and counselling may help manage symptoms, as stress can exacerbate lichen planus.
• Regular Monitoring: Regular follow-up is important to monitor the response to treatment and detect any potential complications, such as squamous cell carcinoma in patients with erosive oral lichen planus.

When to Refer

Referral to a dermatologist or other specialists may be necessary in the following situations:

• Severe or Refractory Cases: If lichen planus does not respond to standard treatments or if the condition is severe, referral to a specialist is advised.
• Oral Lichen Planus: Patients with persistent or erosive oral lichen planus should be referred to a specialist, such as an oral medicine or dermatology consultant, for further evaluation and management.
• Genital Lichen Planus: Referral to a gynaecologist or urologist may be necessary for patients with significant genital involvement, particularly if there is scarring or discomfort during sexual activity.
• Uncertain Diagnosis: If the diagnosis is unclear or if other conditions are suspected, a dermatologist’s input may be necessary.
• Monitoring for Malignancy: Patients with oral lichen planus, particularly erosive forms, should be monitored for potential malignant transformation to squamous cell carcinoma.

References

1. British Association of Dermatologists (2024) Guidelines for the Management of Lichen Planus. Available at: https://www.bad.org.uk (Accessed: 26 August 2024).
2. National Institute for Health and Care Excellence (2024) Lichen Planus: Diagnosis and Management. Available at: https://www.nice.org.uk/guidance/ng106 (Accessed: 26 August 2024).
3. British National Formulary (2024) Topical and Oral Treatments for Dermatological Conditions. Available at: https://bnf.nice.org.uk/ (Accessed: 26 August 2024).