Eczema
How a leaky skin barrier and an allergic type of inflammation feed each other, why the skin becomes dry, itchy and inflamed, how scratching keeps the cycle going and why eczema often comes with asthma and hay fever.
By the end, you can
- Describe how the stratum corneum forms a barrier and the role of filaggrin.
- Explain how barrier defects let irritants, allergens and bacteria in and water out.
- Explain how type 2 inflammation and the itch-scratch cycle sustain eczema.
- Relate dryness, itch, weeping and thickened skin to acute and chronic changes.
- Describe the atopic march and the main complications.
- Recognise the classic appearances, types, diagnostic criteria and tests of eczema, and explain how emollients, topical glucocorticoids, calcineurin inhibitors and biologics act on its mechanism.
What it is
Atopic eczema (atopic dermatitis) is a chronic, relapsing inflammatory skin disease with dry, intensely itchy skin and patches of inflammation. It results from interplay between a faulty skin barrier and type 2 (allergic) inflammation, and often occurs with other atopic conditions: asthma, allergic rhinitis and food allergy. “Eczema” and “dermatitis” are used interchangeably.
2 types to tell apart
- Acute eczema
- Red, swollen, sometimes weeping or blistered skin, from fluid between epidermal cells.
- Chronic eczema
- Thickened skin with exaggerated skin lines (lichenification) from repeated scratching.
Normal function
The skin’s outer barrier
Keratinocytes made in the mature as they rise through the and . At the top they flatten and die, forming the : overlapping cells (“bricks”) sealed by layers of lipids such as ceramides (“mortar”).
A protein called filaggrin helps pack the keratin inside these cells and is broken down into natural moisturising factors that keep the stratum corneum hydrated and slightly acidic. The acid surface restrains harmful bacteria and enzymes.
Together these keep water in and keep irritants, allergens and microbes out. Immune cells in the epidermis and dermis watch for anything that gets through.
Underlying change · Step 1 of 4
A leaky barrier
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Disrupted function · Step 2 of 4
Allergic-type inflammation and the itch-scratch cycle
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Disrupted function · Step 3 of 4
Inflamed, then thickened skin
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Consequences · Step 4 of 4
Infection, the atopic march and daily life
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Symptoms and signs
Symptoms, signs and findings
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Exam detail
Exam detail
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Treatment
How treatment works
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Recap
Recap
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Self-check
Check your understanding
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .