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Latest update 16/06/09
This chapter is set up as follows:
Aetiology
- Lichen Planus (LP) is thought to be an immunologically mediated disorder
- There may be a slight genetic susceptibility
Key diagnostic features
- Symptoms
- Itch – usually very marked
- Onset usually insidious but occasionally lesions develop rapidly
- Distribution
- Can affect any part of the body
- Most commonly found on the flexural aspects of the wrists, the ankles and the lumbar region
- Can become widespread
- Appearance of lesions (morphology)
- Shiny, flat-topped violaceous papules
- White lines (Whickham's striae) transverse the surface
- Linear grouped lesions can grow in scratch marks (Koebner phenomenon)
- Papules tend to flatten after a few months and are replaced by hyper-pigmentation, which can be intense
- In patients with darker skin itching tends to be less of a feature, and hyperpigmentation is a more common presentation. Post-inflammatory hyperpigmentation may be prolonged
- Mucosal lesions
- LP can affect the mouth and vulva. The mouth is involved in approximately 50% of all LP cases, and LP confined to the mouth accounts for about 15% of all cases. Lesions on the female genitalia are fairly common and when present are usually part of a more widepread eruption, but occasionally occur in isolation or in combination with oral symptoms
- Characteristic findings are a white lacework pattern. In the mouth the buccal mucosa is the most commonly affected site. The tongue can also be involved, and less so the gums and lips
- Occasionally lichenoid lesions can arise as the result of contact allergic dermatitis to mercury in amalgam fillings on nearby teeth. Patch tests can confirm the diagnosis and if the fillings are replaced symptoms may improve
- Erosive LP, although uncommon can affect mucosal sites and can be very severe, especially when involving the female genitalia
- Other affected sites
- Scalp – the scal p can be involved in two main ways. A cicatricial alopecia can arise, which is very difficult to distinguish from lupus. Alternatively lichen planopilaris (syn. follicular lichen planus) causes red spiny papules to develop around a cluster of hairs. If left untreated LP of the scalp will scar
- Nails – involved in 10% of cases, fingernails > toenails. Thinning of the nail plate with longitudinal changes predominate. On occasions the nails can be severely affected
- The penis - annular lesions predominate
Other forms of lichen planus
- Hypertrophic LP – this is not uncommon. Large hypertrophic plaques develop especially over the shins and ankles. Such lesions may occur in isolation or as part of a generalised LP
- Annular LP - Although small annular lesions are common in LP, cases consisting predominantly of a few large annular lesions are uncommon. Although annular lesions are characteristically found on the penis, they may be widely scattered. Lesion normally have a narrow rim of activity and a depressed slightly atrophic centre. The differential diagnosis includes granuloma annulare
- Lichenoid drug reactions - cause an LP-like rash. The trunk is the most frequently affected site and the lesions more psoriasiform. Itch can be minimal or absent. Numerous drugs can be responsible including gold, anti-malarials, ACEI, beta-blockers and thiazide diuretics. Resolution of symptoms can be slow after withdrawal of drugs
- Other types of LP include linear, actinic, atrophic, guttate, bullous, pigmented flexural, lichen planus pigmentosus and lichen planopilaris. A mixed LP/discoid lupus erythematosus picture has been described
Investigations
- Lichen Planus can normally be diagnosed without investigations. If the presentation is atypical a biopsy can be helpful - the characteristic histological findings of LP are best demonstrated in biopsies of fully developed lesions
LP and skin cancer
- Malignant change to squamous cell carcinoma is very uncommon
- It is most likely to occur in more aggressive and long-standing LP, and is perhaps therefore most common in ulcerative mucosal lesions
- Clinical findings suggestive of SCC include an enlarging lump or ulcer
Management
- Provide a patient information leaflet
- The prognosis for LP is that 50% of patients clear in 9 months / 85% by 18 months. LP can relapse in 20% of cases
- For the majority the main aim of the treatment is to reduce the intense itch and to treat any scalp lesions to prevent scarring
- Potent (e.g. Elocon ® OD) or super-potent (e.g. Dermovate ® OD) topical steroids may be needed for several weeks
- Moistuisers
- Sedating anit-histamines at night may help with sleep
- As symptoms improve the potency of topical steroids can be reduced
- In order to minimise side-effects of topical steroids it is important to advise patients to treat only itchy red-purple lesions, and not the post-inflammatory hyperpigmentation
- Persistant lesions on the shins (including hypertrophic LP) may require the use of potent / super-potent topical steroids under occlusion, or treatment with intralesional steroids. The easiest form of occlusion is using clingfilm, but where there is more excoriation full occlusion may be required by way of Icthopaste ® and Coban ® bandages
- If symptoms are more troublesome e.g. widespread rash / severe itch, and are not responding to potent / super-potent topical steroids, consider oral prednisolone 20mg OD for 2 weeks or an IM injection of steroids e.g. 80mg Depo-Medrone ® in suitable patients
- Troublesome oral symptoms can be treated with a steroid inhaler, sprayed directly at the affected site (fluticasone appears to be favoured), or steroid pastes such as triamcinolone 0.1% oral paste applied qds
Referral to secondary care
- Patient should be referred for the following:
- Troublesome rash / itch not responding to treatment
- Patients with evidence of scarring alopecia, nail destruction, ulceration or other aggressive forms of lichen planus should be referred urgently to a dermatologist
- Treatments used in secondary care include phototherapy and ciclosporin
- Cases suspicous of SCC (rare) need to referred urgently as a two-week wait
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Figure 1- Lichen Planus of the forearm
Flat-topped violateous papules
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Figure 2 - LP of the wrist
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Figure 3 - Close up of figure 2
Wickham's striae evident (arrows)
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Figure 4 - LP of the buccal mucosa
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Figure 5 - LP of the tongue
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Figure 6 - LP and post-inflammatory hyperpigmentation
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Figure 7 - LP of the nails
Longitudinal ridges
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Figure 8 - Late-stage nail disease with longitudinal ridging and thinning
Such damage is likely to be permanent and non-responsive to treatment. Patients with signs of destructive nail involvement should be referred early
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Figure 9 - LP and nail destruction
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Figure 10 - Lichen planopilaris
Small red papules and scarring alopecia
(copied with kind permission from Dermatoweb)
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Figure 11 - Hypertrophic LP of the shins
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Figure 12 - Annular LP
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Figure 13 - Annular LP
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Figure 14 - Erosive LP of the tongue
(copied with kind permission from Dermatoweb)
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Figure 15 - Squamous cell carcinoma arising from LP |
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Figure 16 - LP of the female genitalia
White lacework pattern
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Figure 17 - Pigmented flexural lichen planus
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Figure 18 - Pigmented flexural lichen planus of the axilla (same patient as above)
The patient also had involvement of the groins and perineal skin
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Figure 19 - LP in a patient with darker skin
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Figure 20 - Follicular lichen planus
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Figure 21 - Same patient as figure 20
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Figure 22 - Lichen planus in Blaschko's lines
Blaschko lines are thought to be pathways of epidermal cell migration and proliferation in the foetus. They are consistently V-shaped on the upper spine, S-shaped on the abdomen, inverted U-shaped from the breast area to the upper arm, and perpendicular down the front and back of the lower extremities. Blaschko's lines never cross the anterior truncal midline but run along it
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