Lichen Planus
Purplish, flat-topped, itchy bumps - the five Ps: Pruritic, Purple, Polygonal, Planar, Papules.
What to look for
Side-by-side comparison
Normal skin
No purple bumps
Lichen planus
Purple flat-topped polygonal bumps
Lichen planus is an inflammatory condition that causes distinctive purplish, flat-topped, polygonal (angular) papules that are characteristically itchy. The classic presentation is remembered by the five Ps: Pruritic (itchy), Purple, Polygonal, Planar (flat-topped), Papules.
It can affect the skin, mouth (oral lichen planus - white lacy lines called Wickham striae), nails, scalp, and genital mucosa. On the skin, it most commonly appears on the wrists, ankles, lower back, and shins. Lesions often show fine white lines on their surface (Wickham striae), best seen with magnification.
The cause is believed to be an immune-mediated reaction, though the trigger is often unknown. Certain medications (ACE inhibitors, NSAIDs, antimalarials), hepatitis C, and dental materials have been associated with lichen planus-like eruptions.
Skin lichen planus often self-resolves within 1-2 years, though it may recur. Oral lichen planus tends to be more chronic. Treatment includes topical corticosteroids, calcineurin inhibitors, and for severe cases, systemic immunosuppressants or phototherapy.
Quick self-check
Does this look like lichen planus? Answer 2 questions.
Are the bumps purple, flat-topped, and angular (polygonal) in shape?
Are they on the wrists, ankles, or inside the mouth?
Risk factors
- Middle age (most common ages 30-60)
- Hepatitis C infection (associated)
- Certain medications
- Stress may trigger flares
- Equal prevalence in men and women
When to see a dermatologist
- ⚠Itchy purple bumps, especially on wrists or ankles
- ⚠White lacy patches inside the mouth
- ⚠Nail changes (ridging, thinning) along with skin or oral lesions
- ⚠Genital sores or discomfort
Often confused with
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Full ABCDE check →Frequently asked questions
Is lichen planus contagious?
No. Lichen planus is an immune-mediated condition and cannot be spread to others.
Does lichen planus go away?
Skin lichen planus often resolves on its own within 1-2 years, though it may leave brownish discoloration. Oral lichen planus tends to be more chronic and may require long-term management.