Lichen Planus (LP)

What will the patient tell you? (History)

Lichen planus is a chronic, immune-mediated inflammatory condition affecting the skin and mucous membranes, common in adults aged 30–60 years.

Onset and Symptoms:

Patients report the gradual onset of a rash composed of "bumps" and flat patches that are classically:

Purple, Polygonal, Planar (flat-topped), Pruritic, Papules, and Plaques (the 6 Ps).
The itch can be severe, often worse at night.
Koebner Phenomenon: New lesions may appear at sites of scratching or skin injury.

Distribution (Crucial to ask about all sites):

Skin (Cutaneous LP): Flexor wrists, forearms, ankles, shins, lower back, neck.
Mouth (Oral LP): White, lacy lines inside the cheeks; sometimes tongue, gums. May be painful or cause burning with acidic foods.
Genitals: Soreness, painful erosions, discharge, or painful intercourse (dyspareunia).
Scalp (Lichen Planopilaris): Itchy, sore scalp, bumpy areas, and patchy hair loss (which may be permanent).

Crucial Note for Darker Skin Tones:

Color: New lesions are typically violaceous, dark purple, or grey-brown, rarely bright red.
Healing: Healing lesions leave long-lasting grey-brown or slate-coloured patches (PIH), which are very noticeable and can persist for months to years.
Pigment-Dominant Variants: Variants like Lichen Planus Pigmentosus (grey-brown macules on the face/neck without a preceding rash) are more common and conspicuous.

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Image Sourced From Skin Sight

What will it look like? (Examination)

Classic Cutaneous LP:

- - Lesion Type: Multiple flat-topped, polygonal papules and plaques.
  - Color: Deep purple, maroon, or grey-brown ("inky") in darker skin tones; reddish-purple in lighter skin.
  - Wickham’s Striae: Fine, white, lacy lines seen on the surface of the lesions (best seen with oil or dermoscopy).
  - Symmetry: Often symmetrical on flexural areas.

Patterns / Variants (More Conspicuous in Darker Skin Tones):

- - Hypertrophic LP: Very thickened, warty, intensely itchy plaques, typically on the shins. In darker skin, these are dark brown and often mistaken for prurigo nodularis. Biopsy may be needed.
  - Lichen Planus Pigmentosus: Ill-defined slate-grey or brown macules on the face, neck, and axillae, often with minimal scale.
  - Actinic LP: Hyperpigmented patches on sun-exposed sites (forehead, cheeks, backs of hands).

Mucosal, Hair, and Nail Findings:

- - Oral LP: White, lacy (reticular) lines on the buccal mucosa. Erosive/ulcerative areas are red, raw, and painful. Note the small but real risk of oral squamous cell carcinoma.
  - Lichen Planopilaris (Scalp): Patchy scarring alopecia with follicular red or violaceous papules, sometimes leading to a receding frontal hairline (Frontal Fibrosing Alopecia).
  - Nails: Longitudinal ridging, grooving, thinning, and potential pterygium formation or complete nail loss.

How can you help? (Treatment)

The goals are to control itch, limit disease activity, prevent scarring (especially on the scalp/genitals), and minimize PIH.

1. General Measures & Counselling:

Reassurance: Explain that LP is autoimmune, not contagious, and not due to poor hygiene.
Medication Review: Look for and potentially adjust lichenoid-inducing drugs (ACE inhibitors, thiazides, NSAIDs, etc.).
Hepatitis C: Consider screening for Hepatitis C based on risk factors.
Sun Protection: Daily broad-spectrum SPF 30 on exposed skin is critical, especially in darker skin, to reduce color contrast and help PIH fade smoothly.

2. Cutaneous LP (Skin):

First-line: High-potency topical corticosteroids (e.g., Clobetasol 0.05% ointment/cream) once or twice daily for a short course, followed by a taper.
Alternative/Steroid-Sparing: Topical Calcineurin Inhibitors (Tacrolimus/Pimecrolimus) for sensitive areas (face, genitals) or maintenance.
Severe/Widespread: Short course of oral corticosteroids (e.g., Prednisolone 30–60 mg daily, tapered over weeks).

3. Oral and Genital LP:

Asymptomatic Oral LP: No treatment; avoid irritants (smoking, alcohol, spicy food).
Symptomatic/Erosive: Very high-potency topical steroid preparations (gels, ointments, mouthwash) or topical calcineurin inhibitors.
Monitor: Regular follow-up for the small risk of squamous cell carcinoma (SCC), especially in erosive/ulcerative disease.

Darker Skin Tones – Specific Treatment Notes:

PIH: Early inflammation control is the best way to minimize PIH. Reassure the patient about the slow return of pigment.
Steroid Risk: Emphasize using a thin layer of topical steroids for a limited course, as steroid-induced hypopigmentation and atrophy are more visible and distressing in darker skin.
Scalp LP: Treat aggressively with intralesional or systemic therapy to halt progression and prevent permanent scarring alopecia.

Sources

NCBI Bookshelf / StatPearls – “Lichen Planus” by David L. Arnold; Karthik Krishnamurthy: https://www.ncbi.nlm.nih.gov/books/NBK526126/

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