Lichen planus

Clinical features:

• Rash is characterised by small, purple, flat-topped polygonal papules that are intensely pruritic
• It is common on the flexors of the wrists and the lower legs, but can occur anywhere
• The lesions may fuse into plaques, especially on the lower legs and in Africans
• Hyperpigmentation is common after resolution of lesions, especially in patients with pigmented skin
• If lesions occur in the scalp, they may cause a scarring alopecia
• Mucosal involvement is seen in 50% of cases:
• The mouth is the most commonly affected, but the anogenital region can be involved
• It can present as lacy white streaks, white plaques or as ulceration
• Prominent symptom is pain, rather than pruritus

Prognosis:

• The condition often clears within 2 years, but can recur at intervals
• The hypertrophic and atrophic variants and mucosal disease are more persistent, lasting years
• Ulcerative mucosal disease is pre-malignant

Treatment:

• Use of potent topical steroids (e.g. 0.05% clobetasol proprionate)
• Occasional use of oral prednisolone (30mg od for 2-4 weeks)
• Resistant cases may respond to:
• UV therapy
• Oral retinoids (0.5mg/kg daily)
• Azathioprine (50-100mg daily)