Overview

Lichen planus is a chronic inflammatory condition affecting the skin, scalp, nails, and mucous membranes (mouth, genitals). It causes shiny flat-topped purple-red bumps on skin and white lacy patches in the mouth. Thought to be an autoimmune reaction, it may be triggered by medications, hepatitis C, or stress.

Symptoms

• Skin: flat-topped shiny purple or violet bumps (papules), intensely itchy; most common on wrists, inner forearms, ankles, lower back
• White streaks on lesion surfaces (Wickham's striae)
• Oral: white lacy patches on inner cheeks/gums; painful erosive form causes burning open sores
• Scalp: scarring hair loss (lichen planopilaris); nail ridging, thinning, or loss

Causes & Risk Factors

• Autoimmune T-cell reaction attacking skin and mucosal cells
• Hepatitis C infection — screen all patients with lichen planus
• Certain medications: ACE inhibitors, NSAIDs, antimalarials, beta-blockers
• Dental amalgam contact (oral lichen planus); stress

Complications

• Scarring hair loss; post-inflammatory hyperpigmentation common in darker skin tones
• Oral erosive lichen planus significantly impairs eating and oral hygiene
• Very rarely, oral lichen planus may progress to oral squamous cell carcinoma — regular follow-up is essential

Diagnosis

Clinical diagnosis by characteristic appearance. Skin biopsy confirms. Hepatitis B and C serology for all patients. Liver function tests. Patch testing if dental material allergy suspected.

Treatment

• Topical corticosteroids: first-line for skin and oral lichen planus
• Topical calcineurin inhibitors (tacrolimus): effective especially for oral and genital forms
• Systemic corticosteroids for severe/widespread cases; hydroxychloroquine or acitretin for resistant cases
• Treating hepatitis C may resolve associated lichen planus; switch causative medications if identified

Prevention

• Early treatment minimises scarring; screen and treat hepatitis C when indicated
• Regular dental and dermatology follow-up for oral lichen planus to monitor for malignant change

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