Lichen planus Flashcards

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1
Q

What is lichen planus?

A
  • chronic, inflammatory, pruritic skin disorder
  • limbs, esp flexor surfaces
  • mucous membranes
  • genitals including inside vagina
  • 6Ps: planar, polygonal, papules <5mm, plaques >5mm, purple, pruritic
  • can be types according to location
  • cause not well understood
  • may be a T-cell mediated autoimmune disorder
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2
Q

Epidemiology of lichen planus?

A
  • affects adults over 40
  • 1-4% prevalence world wide
  • 50% have oral lichen planus
  • 10% affects nails
  • 1M : F1.5
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3
Q

Aetiology and pathology of lichen planus?

A

Pathology:

  • T-cell mediated autoimmune disorder
  • T-cell attack an as yet unidentified protein in skin and nails

Aetiology:

  • genetic predisposition
  • physical and psychological stress
  • skin trauma; occurs at surgery sites or herpes zoster sites
  • systemic viral can trigger LP eg hep B or C
  • contact dermatitis can precipitate LP
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4
Q

Presentation of lichen planus?

A

Typically an acute presentation:

  • flexors (elbows, knees)
  • ITCHY
  • not usually painful
  • may affect genitals
  • inside mouth and sometimes vagina (wickhams striae)
  • 6Ps: planar, polygonal, papules <5mm, plaques >5mm, purple, pruritic
  • distinct, purpuric, raised lesions
  • ocassionaly lesions blister
  • after healing they leave small flat brown discoloured circles

Mucous surfaces:

  • white, slightly raised lesions (Wickhams striae and lace)
  • appear like small ulcers or white streaks
  • tongue or inside cheeks
  • can be asymptomatic or very painful

Nails:

  • affects 10%
  • longitudinal lines

Scalp

  • usually spared
  • if affected can cause severe scarring and alopecia

Subtypes:

  • hypertrophic LP, thick, raised lesions, leave hyperpigmentation when they resolve
  • erosive / ulcerative, often painful and on mucosal surfaces
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5
Q

Diagnosis of lichen planus is usually clinical but what might be seen on skin biopsy?

A
  • saw tooth pattern of epidermal hyperplasia
  • T-cell infiltration of dermis
  • reduced melanocytes
  • direct immunofluorescence show globular deposits of Ig (usually IgM, sometimes IgG and IgA)
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6
Q

Differential diagnosis when thinking lichen planus?

A

Consider:

  • drug reaction; lichenoid drug reaction: gold, hydroxychloroquine, captopril, quinine, thiazide diuretics
  • eczema
  • psoriasis
  • candidiasis
  • lichen sclerosis (for external genitals)
  • pemphigus
  • sarcoidosis
  • basal cell carcinoma when single lesions
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7
Q

Management of lichen planus?

A

Topical steroids

Other: azathioprine, mycophenylate, retinoids, hydroxychloroquine

Oral lesions are harder to treat.
Any scarring is permanent.

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8
Q

Complication of lichen planus?

A
  • hyperpigmentation from previous lesion
  • 1% lifetime risk of oral squamous cell carcinoma (higher is smoker, alcohol, hep C)
  • rarely carcinoma of vulva is associated
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