Lichen Planus

Question 1

What is lichen planus (LP)?

Answer 1

A chronic inflammatory autoimmune condition affecting the skin, mucous membranes, hair, and nails, characterized by pruritic, polygonal, purple papules and plaques.

Question 2

Which areas are commonly affected by lichen planus?

Answer 2

Skin (wrists, forearms, ankles, lower back).

Mucous membranes (oral, genital).

Scalp (lichen planopilaris).

Nails.

Question 3

Who is most commonly affected by lichen planus?

Answer 3

Adults aged 30–60 years, with a slight female predominance.

Question 4

What causes lichen planus?

Answer 4

The exact cause is unknown, but it is believed to be an autoimmune response targeting basal keratinocytes, possibly triggered by:

Viral infections (e.g., hepatitis C).

Medications (drug-induced LP).

Stress or trauma (Koebner phenomenon).

Question 5

What is the pathophysiology of lichen planus?

Answer 5

T-cell-mediated immune response leads to destruction of basal keratinocytes, causing inflammation and characteristic histologic changes.

Question 6

What are the characteristic skin lesions in lichen planus?

Answer 6

Pruritic, purple, polygonal, planar papules and plaques.

Wickham’s striae: Fine, white, lacy streaks on the surface of the lesions.

Question 7

What is the Koebner phenomenon in lichen planus?

Answer 7

New lesions develop at sites of trauma or injury to the skin.

Question 8

How does oral lichen planus present?

Answer 8

Reticular form: White, lacy patches (Wickham’s striae).

Erosive form: Painful ulcers or erythematous patches.

Bullous form: Rare, with fluid-filled blisters.

Question 9

What are the features of genital lichen planus?

Answer 9

Vulva: Erythematous or erosive lesions, often painful.

Penis: White, lacy patterns or erosions.

Question 10

How does lichen planopilaris affect the scalp?

Answer 10

Scalp inflammation causing scarring alopecia.

Hair follicle destruction leading to permanent hair loss.

Question 11

What are the nail changes in lichen planus?

Answer 11

Longitudinal ridging or splitting.

Nail thinning or loss (onycholysis).

Pterygium formation (fusion of the proximal nail fold to the nail bed).

Question 12

What are the main types of lichen planus?

Answer 12

Cutaneous LP.
Oral LP.

Genital LP.

Lichen planopilaris (scalp).

Nail LP.

Drug-induced LP.

Lichenoid dermatitis (LP-like reaction).

Question 13

How is lichen planus diagnosed?

Answer 13

Clinical appearance and history.

Skin biopsy: Confirms diagnosis with characteristic histologic findings.

Question 14

What are the histopathological features of lichen planus?

Answer 14

Hyperkeratosis and hypergranulosis.

Band-like lymphocytic infiltrate at the dermoepidermal junction.

Saw-tooth rete ridges.

Civatte bodies (apoptotic keratinocytes).

Question 15

What tests should be considered in oral or erosive LP?

Answer 15

Screening for hepatitis C virus (HCV), as it is associated with LP.

Question 16

What are the first-line treatments for cutaneous lichen planus?

Answer 16

Topical corticosteroids: High-potency (e.g., clobetasol).

Topical calcineurin inhibitors: Tacrolimus or pimecrolimus for sensitive areas.

Question 17

What systemic treatments are used for severe or widespread LP?

Answer 17

Oral corticosteroids (e.g., prednisone).

Retinoids (e.g., acitretin).

Immunosuppressants (e.g., methotrexate, azathioprine, or cyclosporine).

Question 18

How is oral or mucosal lichen planus managed?

Answer 18

Topical corticosteroids or calcineurin inhibitors.

Mouth rinses with corticosteroids or anesthetics.

Systemic treatments for refractory cases.

Question 19

What are supportive treatments for pruritus in LP?

Answer 19

Oral antihistamines and emollients.

Question 20

What are the potential complications of lichen planus?

Answer 20

Post-inflammatory hyperpigmentation.

Scarring alopecia (lichen planopilaris).

Nail loss or scarring.

Malignant transformation (rare, especially in oral LP).