🧑⚕️ FREE MSRA PODCAST – Lichen Planus: Mastering the Purple Pruritic Rash
🎯 A deep dive into lichen planus, one of the MSRA’s favourite inflammatory skin conditions—covering core facts, memorable mnemonics, diagnosis, management, and red flags.
Key Learning Points
🔍 Definition
• Lichen planus is a chronic, immune-mediated inflammatory disorder affecting the skin, mucous membranes, hair, and nails.
• Classic description: the “6 Ps”—Pruritic, Purple, Polygonal, Planar, Papules, and Plaques.
• Wickham striae: fine, white, lacy lines seen on the surface of papules and in the mouth.
💡 Causes & Risk Factors
• Precise cause unknown, but believed to be T-cell mediated autoimmunity.
• Strong associations: Hepatitis C infection (particularly oral LP), certain medications (e.g., NSAIDs, beta-blockers, thiazides), stress, and family history.
🧬 Pathophysiology
• CD8+ T-cell attack on basal keratinocytes in the skin and mucous membranes
• Triggers: drugs, viral infections, genetic susceptibility
🩺 Clinical Features
• Itchy, purple, flat-topped, polygonal papules—flexor wrists, forearms, shins, lumbar region
• Wickham striae: white, lacy lines (esp. in oral or genital mucosa)
• Oral/genital ulcers may be painful and chronic
• Nail changes: ridging, thinning, pterygium, or loss
• Scalp involvement: lichen planopilaris—patchy, permanent hair loss
• Post-inflammatory hyperpigmentation is common after lesions heal
📌 Mnemonic: The 6 Ps
• Pruritic (itchy)
• Purple
• Polygonal
• Planar
• Papules
• Plaques
📝 Differential Diagnoses
• Psoriasis
• Eczema
• Lichenoid drug eruptions
• Chronic eczema (simplex)
• Oral: Thrush, leukoplakia, oral lichenoid reaction
🔬 Diagnosis
• Clinical appearance often sufficient
• Skin or mucosal biopsy—shows “sawtooth” lymphocytic infiltrate, hypergranulosis, basal cell degeneration
• Test for hepatitis C if risk factors or oral involvement
💊 Management
• Remove any causative drug if identified
• First line: potent topical corticosteroids (with or without occlusion)
• For oral/genital LP: topical steroids (mouthwashes, pastes), local anaesthetics
• Widespread, severe, or resistant disease: systemic corticosteroids, immunosuppressants (azathioprine, mycophenolate), retinoids, phototherapy (UVB/PUVA)
• Antihistamines for pruritus
• Regular monitoring for oral/genital LP (risk of squamous cell carcinoma)
📈 Prognosis
• Cutaneous LP is often self-limiting (resolves in 1–2 years), but recurrences may occur
• Oral/genital LP: chronic, relapsing course, higher risk of persistent symptoms and malignant change
• Watch for post-inflammatory pigmentation, scarring (scalp/nails), or persistent discomfort
⚠️ Complications
• Malignant transformation (especially oral/genital LP; ~1% lifetime risk—higher with smoking, Hep C)
• Scarring, particularly on the scalp (permanent alopecia) or nails
• Persistent pain, ulceration, or impaired quality of life
📎 More MSRA Revision for Lichen Planus:
📝 Revision Notes: https://www.passthemsra.com/topic/lichen-planus-revision-notes/
💬 Flashcards: https://www.passthemsra.com/topic/lichen-planus-flashcards/
🧠 Accordion Q&A: https://www.passthemsra.com/topic/lichen-planus-accordion-qa-notes/
🚀 Rapid Quiz: https://www.passthemsra.com/topic/lichen-planus-rapid-quiz/
🧪 Full Quiz: https://www.passthemsra.com/quizzes/lichen-planus/
🎓 Dermatology Course: https://www.passthemsra.com/courses/dermatology-for-the-msra/
🌐 For the full premium revision toolkit:
https://www.passthemsra.com
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