Lichen planus
Also called LP
The disease of the six Ps: purple, polygonal, planar, pruritic papules and plaques, classically at the wrists, with lacy white Wickham striae on the surface and often in the mouth.
Mucosal surface, where pigmentation does not change the white reticular pattern
How it looks
Multiple violaceous, polygonal, flat-topped papules with fine white reticular striae on the volar wrists.
Rose is the lesion, grey the pattern the lesions make, green where on the body it lives.
Across skin tones
The violaceous hue is often deeper and the post-inflammatory hyperpigmentation dramatic and long-lasting in deeply pigmented skin; hypertrophic LP on the shins is also more common.
Symptoms & course
- Itch, often intense
- Oral lesions may burn with acidic food
Diagnostic approach
- Examine the mouth, lacy white buccal striae support the diagnosis
- Biopsy when atypical
- Consider hepatitis C association in the right context
Differential, and how to separate them
- Psoriasis
Favours it: Silvery scale, extensor sites
Against it: LP is violaceous, flat-topped, and favours wrists and mucosa
Management principles
- Potent topical corticosteroids first-line
- Antihistamines for itch
- Specialist care for erosive oral disease
Clinical pearl: Check the wrists, the mouth, and the shins, three stations that make the diagnosis at the bedside.
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