Dermatology - Blistering disorders Flashcards
What are the different categories of blistering skin disorders?
Blistering skin disorders can be divided into
- immunobullous disease (e.g. bullous pemphigoid, pemphigus vulgaris)
- blistering skin infections (e.g. herpes simplex)
- others (e.g. porphyria cutanea tarda)
What determines the fragility of blisters?
The fragility of blisters is determined by the level of split in the skin:
- an intra-epidermal split (within the epidermis) causes blisters to rupture easily
- sub-epidermal splits (a split between the epidermis and dermis) causes blisters to be less fragile
Name some common causes of blistering?
Common causes of blistering include”
- impetigo
- insect bites
- herpes simplex infection
- herpes zoster infection
- acute contact dermatitis
- pompholyx (vesicular eczema of the hands and feet)
- burns
What is bullous pemphigoid?
Bullous pemphigoid is an autoimmune condition causing sub-epidermal blistering of the skin. This is secondary to the development of antibodies against hemidesmosomal proteins BP180 and BP230.
What are the clinical features of bullous pemphigoid?
Bullous pemphigoid is more common in elderly patients. Features include
itchy, tense blisters typically around flexures
the blisters usually heal without scarring
mouth is usually spared*
*in reality around 10-50% of patients have a degree of mucosal involvement. It would however be unusual for an exam question to mention mucosal involvement as it is seen as a classic differentiating feature between pemphigoid and pemphigus.
What skin biopsy features are characteristic of bullous pemphigoid?
Immunofluorescence shows IgG and C3 at the dermoepidermal junction.
How should bullous pemphigoid be managed?
Referral to dermatologist for biopsy and confirmation of diagnosis.
General measures including wound dressing and monitoring for infection.
Oral corticosteroids are the mainstay of treatment (especially for widespread disease)
Topical corticosteroids, immunosuppressants (e.g. azothioprine, mycophenolate, methotrexate) and antibiotics are also used.
Combination agents of tetracycline and nicotinamide is a common antibiotic regime.
What is pemphigus vulgaris?
Pemphigus vulgaris is an autoimmune disease caused by antibodies directed against desmoglein 3, a cadherin-type epithelial cell adhesion molecule. It is more common in the Ashkenazi Jewish population.
What are the important clinical features of pemphigus vulgaris?
- Mucosal ulceration is common and often the presenting symptom. Oral involvement is seen in 50-70% of patients
- Skin blistering - flaccid, easily ruptured vesicles and bullae. Lesions are typically painful but not itchy. These may develop months after the initial mucosal symptoms. Nikolsky’s describes the spread of bullae following application of horizontal, tangential pressure to the skin
- Acantholysis on biopsy
How is pemphigus vulgaris managed?
General measures
Immunosuppressants
Steroids
What is pompholyx?
Pompholyx is a type of eczema which affects both the hands (cheiropompholyx) and the feet (pedopompholyx). It is also known as dyshidrotic eczema.
What are the features of pompholyx?
Small blisters on the palms and soles
Pruritic, sometimes burning sensation
Once blisters burst skin may become dry and crack
Management is:
- cool compress
- emollients
- topical steroids
What is dermatitis hepatiformis? What are the key clinical features?
Dermatitis herpetiformis is an autoimmune blistering skin disorder associated with coeliac disease. It is caused by deposition of IgA in the dermis.
Features are itchy, vesicular skin lesions on the extensor surfaces (e.g. elbows, knees, buttocks).
How is dermatitis hepatiformis diagnosed?
Skin biopsy: direct immunofluorescence shows deposition of IgA in a granular pattern in the upper dermis.
How is dermatitis hepatiformis treated?
gluten-free diet
dapsone
