Lichen planus is an immune-driven inflammatory disease that can affect the skin, mouth, genitals, scalp and nails, most often in middle-aged adults. Skin lesions often fade within 1 to 2 years, while mouth disease tends to last longer.
Key symptoms
- Very itchy, flat-topped bumps, often on wrists, ankles and lower back
- New bumps appearing along scratch lines
- Burning or soreness in the mouth with spicy food
- Painful genital sores or pain with sex
- Thin nails or patchy hair loss
What you find on exam
- The 5 Ps: purple, polygonal, planar, pruritic papules and plaques
- Fine white lines on top of lesions (Wickham striae)
- Lacy white streaks on the inner cheeks, sometimes with erosions
- Lesions along lines of trauma (Koebner phenomenon)
- Nail ridging and splitting, scarring hair loss
Tests
- Skin biopsy if the diagnosis is unclear
- Hepatitis C antibody test, since the two are linked
- Biopsy of a mouth sore that does not heal, to rule out cancer
Treatment basics
- High-potency topical steroid such as clobetasol for skin lesions
- Topical steroid gel or tacrolimus for mouth disease
- Oral antihistamines for itch
- Widespread disease: short course of oral prednisone, phototherapy or acitretin
- Stop a suspected trigger drug; good oral hygiene and regular dental checks
Red flags
- Mouth or genital sore that does not heal or becomes thick
- Trouble swallowing (esophageal involvement)
- Rapidly spreading rash after starting a new medicine
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Sources: NCCPA PANCE Content Blueprint; NBOME COMLEX-USA clinical presentations; AAMC Core Entrustable Professional Activities (Core EPAs). Written by Making Synapses. Making Synapses is not affiliated with these organizations.