Lichen Planus ICD-10: L43.9

Chronic inflammatory skin disease / Immune-mediated

Often searched as: purple itchy bumps on wrist, flat purple bumps on skin, white lacy patches in mouth, itchy bumps on ankles and wrists, mouth sores white streaks, polygonal bumps on skin, shiny flat itchy bumps, lichen planus photos…

Clinical urgency level

lowmediumhigh

Systems Affected

skinoral mucosagenitalsnailsscalp (lichen planopilaris variant)

Severity Levels

mild

A few itchy purple papules on the wrists or ankles, no mucosal involvement, self-limiting — manageable with topical corticosteroids.

moderate

Widespread skin lesions, oral or genital involvement, significant itch or pain — requires potent topical or systemic treatment.

severe

Extensive erosive oral or genital lichen planus causing eating difficulty or pain, hypertrophic lichen planus with scarring, or scarring scalp involvement — requires specialist management; low but real malignant transformation risk in chronic oral forms.

Red Flags

Painful oral sores or white lacy patches that make eating or swallowing difficult
Erosive genital lesions causing significant pain or scarring
Skin lesions not responding to topical treatment after 4–6 weeks
Hypertrophic (very thick, dark) plaques especially on the legs — higher malignant transformation risk
Ulcerating or non-healing patches in the mouth lasting more than 3 weeks
Hair loss with scalp redness and scaling (lichen planopilaris — scarring alopecia risk)

Clinical Presentation

Lichen planus — classic flat-topped violaceous papules on the wrist

Source: Wikimedia Commons (CC BY-SA 3.0 )

Oral lichen planus — white lacy Wickham's striae on buccal mucosa

Source: Wikimedia Commons (CC BY-SA 3.0 )

When to See a Doctor

See a dermatologist if you develop itchy purple bumps on your wrists, ankles, or lower back, or white lacy patches inside your mouth. Oral lichen planus always warrants professional evaluation — both for treatment and because chronic erosive forms carry a small risk of oral cancer over many years. Genital involvement also requires specialist care.

Differential Diagnosis

Psoriasis (silvery plaques — different distribution and texture)
Eczema / atopic dermatitis
Lichenoid drug reaction (identical histology — medication history key)
Secondary syphilis (papular — serologic testing)
Oral leukoplakia (white patches — biopsy needed)
Lupus erythematosus (overlap possible)
Graft-versus-host disease (lichenoid reaction post-transplant)

Comorbidities

Hepatitis C infection (strong association — especially in Mediterranean populations)
Thyroid disease
Other autoimmune conditions
Anxiety and depression (chronic itchy condition with significant QoL impact)
Low risk of oral squamous cell carcinoma in chronic erosive oral lichen planus (~1–3%)

Prognosis

Cutaneous lichen planus often resolves spontaneously within 1–2 years in most patients, though post-inflammatory hyperpigmentation can persist for months. Oral and genital forms tend to be more chronic and may persist for years requiring ongoing management. Hypertrophic lichen planus on the legs is particularly stubborn. Treatment with topical corticosteroids, calcineurin inhibitors, and systemic agents (retinoids, methotrexate) achieves good symptom control. The small risk of malignant transformation in chronic oral erosive LP warrants long-term follow-up.

Detailed Overview

Causes, Symptoms, and When to Take Action Lichen planus is a chronic inflammatory, immune-mediated condition affecting the skin, mucous membranes, hair, and nails. It spans a wide clinical spectrum, with the most common manifestations occurring on the skin and in the oral cavity. How It Looks Texture: Often appears as flat-topped, polygonal papules — sometimes with fine scales Color: Typically purplish or reddish, depending on skin tone Shape: Distinctive polygonal shapes, with irregular borders Location: Common sites include the wrists, ankles, oral mucosa, scalp, and genital areas Why Does It Appear? The development of lichen planus involves an immune-mediated attack — specifically, T-cell-driven inflammation — targeting basal epidermal cells. Genetic predispositions and environmental triggers may contribute. Should You Be Concerned? While not life-threatening, lichen planus can significantly affect quality of life. Some variants — particularly chronic oral or hypertrophic forms — may carry a low risk of malignant transformation, warranting closer monitoring. Can You Prevent It? There is no known prevention. You can support your skin health by avoiding known triggers, monitoring for persistent lesions, and seeking professional evaluation if lesions are painful or chronic. 👉 How Piel AI Can Help Piel AI allows you to track visible lesions over time via regular imaging. While not a diagnostic tool, it helps identify changes or flare patterns and supports informed discussions with your healthcare provider. Summary Lichen planus is a chronic inflammatory condition affecting skin, mucosa, hair, and nails. It often presents as purplish, polygonal papules that may be itchy. Though benign, chronic or mucosal forms may require careful observation. Regular monitoring and vigilant care can aid in early detection of changes.

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