Lichen planus

Question 1

Define lichen planus.

Answer 1

A pruritic, chronic inflammatory dermatosis resulting from keratinocyte apoptosis that affects the skin, mucous membranes, genitalia, scalp (lichen planopilaris), and nails

Question 2

How common is lichen planus?

Answer 2

• < 1% prevalence in US
• Usually 30-60yrs
• F > M

Question 3

What is the pathophysiology of lichen planus?

Answer 3

CD4 and CD8 T cell destruction/apoptosis of basal keratinocyts at the dermal-epidermal junction

Question 4

What are the risk factors for lichen planus?

Answer 4

Hepatitis C - may induce susceptibility by changing cytokine expression in some patientsl; 20% of patients with new LP are Hep C positive

Question 5

What are the clinical features of lichen planus?

Answer 5

• Intense pruritus (80%)
• Violaceous, flat-topped papules or plaques - most common on the palms, soles, genitalia and flexor surfaces of the arms
• Wickham’s striae - polygonal rash with white lines pattern on the surface
• Koebner phenomenon - new lesions appearing at sites of trauma
• Mucosal erosions, lacy white network
• Scarring alopecia
• Nails - thinning of nail plate, longitudinal ridging

Question 6

How do you diagnose lichen planus?

Answer 6

Clinical diagnosis

Other: Biopsy - a band-like lymphocytic infiltrate at the dermo-epidermal junction, necrotic keratinocytes, hyperkeratosis, and hypergranulosis

Question 7

What is the management of lichen planus?

Answer 7

• Potent topical corticosteroid e.g. clobetasol 0.05% - first line. Oral corticosteroid e.g. prednisolone 2-6 weeks then tapered in more extensive disease.
• Benzydamine mouthwash - for oral lichen planus

Other:

• Retinoid
• Phototherapy - PUVA or narrowband UVB
• Antihistamine e.g. chlorphenamine
• Immunosupression/immunomodulation - e.g. ciclosporin, azathioprine, methotrexate, MMF

Question 8

What is shown?

Answer 8

White lace pattern on buccal mucosa in lichen planus

Question 9

Name 3 drug causes of lichenoid eruptions.

Answer 9

• Gold
• Quinine
• Thiazides

Question 10

What are the complications and prognosis of lichen planus?

Answer 10

Scarring alopecia
Squamous cell carcinoma - in erosive mucosal disease

Prognosis - chronic so may remain unresponsive to treatment or may recur when treatment is discontinued.