Synopsis
Recognise cutaneous, mucosal, scalp, nail and pigmentary lichen planus, confirm atypical disease safely, protect scarring sites, and monitor persistent lesions for malignant change.
- Classic cutaneous lichen planus is an itchy eruption of flat-topped shiny papules, often violaceous or darker than surrounding skin, with fine pale Wickham striae on wrists, ankles and lower back.
- Examine mouth, genital skin, scalp and nails with explanation and consent: specialised-site disease can scar even when the ordinary skin eruption is modest.
- In darker skin, papules may be deep brown or subtly purple, pale striae remain useful, and grey-brown post-inflammatory pigment can persist long after active inflammation.
Key red flags
A persistent indurated, ulcerated, bleeding or enlarging lesion within oral, genital or hypertrophic disease needs urgent biopsy assessment for squamous cell carcinoma.
Reticular white lacy lines may be asymptomatic, while erosive gingival or buccal disease is painful and affects eating. Examine the full mouth and palpate persistent ulcerated or indurated areas.
Investigation priorities
Map cutaneous, oral, genital, scalp and nail involvement and identify sites at risk of scarring or cancer.
Management branches
Typical skin papules without scarring-site disease, significant erosion or malignant warning features.
- Explain the often self-limiting course, avoid skin injury, use emollient or soap substitute for comfort, and document active papules separately from residual pigment.
- Observe asymptomatic limited disease; for itch or active inflammation, apply a prescribed potent or very potent topical corticosteroid carefully once daily to papules.