Lecture 4 Eczema Flashcards
T cell responsible for acute stage of eczema
Th2
T cel responsible for chronic sage of eczema
Th1
Clinical features of Atopic eczema
• Itchy skin condition in the last 12 months
Plus 3 of the following: • Onset before age 2 • History of flexural involvement • History of generally dry skin • History of other atopic disease • History in 1st degree relative if under 4 yrs
Pathogenesis of Eczema
– Key role for Filaggrin gene
– Atopic family history
- Epidermal barrier dysfunction
- Environmental factors
- Immune system dysregulation
Pathology of eczema
- Spongiosis (intercellular oedema) within the epidermis.
- Acanthosis (thickening of the epidermis).
- Inflammation - Superficial perivascular lymphohistiocytic infiltrate
Histological features of acute dermatitis
Oedema in epidermis
superficial perivascular infiltrate with lymphocytes, histiocytes and occasional neutrophils and eosinophils.
Histological features of chronic dermatitis
- Chronic spongiotic dermatitis- degree of spongiosis is often mild and difficult to appreciate
- Significant acanthosis which may show a psoriasiform pattern with hyperkeratosis, hypergranulosis and miminal parakeratosis.
- Fibrosis of the papillary dermis may be present.
Clinical features of Atopic dermatitis/eczema
• Itch • Distribution – Flexures, Neck, Eyelids, Face, Hands and feet – Tends to spare nappy area • Acute changes – Pruritus, Erythema, Scale, Papules, Vesicles – Exudate, crusting, excoriation • Chronic changes – Lichenification, Plaques, Fissuring
External types eczema
• Contact dermatitis – Irritant – Allergic • Lichen simplex • Photoallergic or photoaggravated eczema
Internal types of eczema
– Atopic – Discoid – Venous – Seborrhoeic dermatitis – Pompholyx – Juvenile plantar dermatitis • Asteatotic
What type of sensitivity is allergic contact dermatitis
Type 4 Hypersensitivity
Delayed can take 48-72 hours
What are the causes of irritant contact dermatitis
- Friction- micro-trauma, cumulative
- Environmental factors
– Overexposure to water
– Chemicals such as acids, alkalis, detergents and solvents
What occupations increased for risk of developing irritant contact dermatitis
Hairdressers
NHS staff
Cleaners
Describe the process of patch testing
- Applied Monday (3 days)
- Remove Wednesday
- Re-assess Friday (2 days after removing)
What is Seborrhoeic dermatitis in infants
- Distinctive pattern
- Predilection for scalp, proximal flexures.
- <6months age usually.
- Often clears within weeks of treatment