🧬 Chapter 699: Disorders of Keratinization

Nelson Textbook of Pediatrics 22nd Edition | Ichthyoses: ichthyosis vulgaris, X-linked ichthyosis, lamellar ichthyosis, CIE, harlequin ichthyosis, epidermolytic ichthyosis, Netherton syndrome, Sjogren-Larsson syndrome, Refsum syndrome, KID syndrome. Palmoplantar keratodermas: Unna-Thost, Vohwinkel, Papillon-Lefevre, pachyonychia congenita.

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📋 30 MCQs — Disorders of Keratinization

📇 High‑Yield Review Cards | Ichthyoses & Keratodermas

🩺 Clinical Feature → Diagnosis & Key Associations

Select a clinical presentation to learn the diagnosis, genetic defect, and management.

📋 Stepwise Approach to Ichthyoses & Keratodermas

🔑 Key Principles — Nelson Chapter 699
• Ichthyosis vulgaris: FLG mutation, autosomal dominant/semidominant. Fine white scale, extensor surfaces, associated with atopy. Emollients, urea, lactic acid.
• X-linked ichthyosis: STS deficiency. Large dark scales, sparing flexures, corneal opacities. Emollients, keratolytics.
• Lamellar ichthyosis / CIE: AR, TGM1/ABCA12/other. Collodion baby → large dark scales (LI) or fine white scale + erythroderma (CIE). Oral retinoids, emollients.
• Harlequin ichthyosis: ABCA12, severe at birth, thick plates, ectropion, eclabion. Intensive care, oral retinoids.
• Epidermolytic ichthyosis: KRT1/KRT10, blistering at birth → hyperkeratosis with flexural ridges. Oral retinoids, wound care.
• Netherton syndrome: SPINK5, ichthyosis linearis circumflexa, trichorrhexis invaginata (bamboo hair), atopy, elevated IgE. Topical steroids, antihistamines.
• Sjogren-Larsson: ALDH3A2, ichthyosis + spastic diplegia + intellectual disability. Emollients, retinoids.
• Palmoplantar keratodermas: Emollients, keratolytics, oral retinoids for severe cases.

    ⚡ Reflex Prompts — Keratinization Disorder Scenarios

    📖 Summary: Disorders of Keratinization (Nelson 699)