Short answer · Medically reviewed summary · Last updated: 2026-04-06
Lichen planus is a chronic, non-infectious inflammatory condition that typically causes itchy, purple-colored bumps on the skin or lacy white patches on mucous membranes like the mouth. How the Body is Affected Lichen planus primarily affects the skin, mouth, and sometimes the nails, hair, or genital regions. In the mouth (oral lichen planus), patients often experience burning sensations or painful sores, which can make eating or drinking difficult.
What is Lichen Planus
What is Lichen Planus? Plain-language, medically reviewed definition plus the lived reality told by patients.
Lichen planus is a chronic, non-infectious inflammatory condition that typically causes itchy, purple-colored bumps on the skin or lacy white patches on mucous membranes like the mouth.
How the Body is Affected
Lichen planus primarily affects the skin, mouth, and sometimes the nails, hair, or genital regions. In the mouth (oral lichen planus), patients often experience burning sensations or painful sores, which can make eating or drinking difficult. Skin lesions, known as the "six Ps"—planar (flat-topped), purple, polygonal, pruritic (itchy), papules, and plaques—are the hallmark of the condition. When it affects the scalp, it can lead to hair loss (lichen planopilaris), and nail involvement may cause ridges or thinning.
Subtypes and Demographics
There are several clinical variants of Lichen Planus, including the classic cutaneous form, oral, genital, and the more aggressive lichen planopilaris. While the exact prevalence is difficult to determine, it is estimated to affect approximately 0.1% to 4% of the general population worldwide. Lichen planus most commonly appears in adults between the ages of 30 and 60, with oral forms occurring slightly more frequently in women. There is no specific geographic predilection; it is a global condition.
Pathophysiology and Differentiation
The underlying mechanism of Lichen Planus is widely considered to be a T-cell-mediated autoimmune response, where the body’s immune system mistakenly attacks its own basal epithelial cells. Unlike fungal infections or contact dermatitis, Lichen Planus is characterized by a specific inflammatory pattern visible under a microscope, often referred to as a "saw-tooth" rete ridge appearance. Unlike psoriasis, which presents with silvery scales, Lichen Planus lesions are typically smooth, shiny, and flat-topped.
Disclaimer: This information is for educational purposes and does not replace professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.
References
- NIH Genetic and Rare Diseases Information Center (GARD): Lichen Planus
- Orphanet: Portal for rare diseases and orphan drugs
- American Academy of Dermatology (AAD): Lichen planus overview
