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BLISTERING DISEASES
1. INTRODUCTION
Blistering diseases are defined as skin disorders that primarily give rise to vesicles (i.e. 5 mm or less in diameter) or bullae (i.e. over 5 mm in diameter). Blisters are accumulation of fluid lying within or below the epidermis. Blistering diseases can be classified according to the site of cleavage (see table 1). Only the common conditions will be discussed below.
The diagnosis of blistering diseases can sometimes be aided by physical findings.
(i) Morphology of blister :
- Subepidermal blister occurs between the dermis and the epidermis. It contains thick wall and may contain blood.
- Intraepidermal or subcorneal blister usually has very thin roof. Intact blisters may not be easily detected but leaving erosions only.
Palm and sole blisters usually remain intact because of the thick stratum corneum.
- Grouped vesicles along a dermatome is characteristic of herpes infection.
(ii) Site of blister :
- Pompholyx occurs at palm and soles
- Blisters at sites of frequent trauma suggest of Epidermolysis Bullosa.
(iii) Mucosal membrane involvement is frequently found in pemphigus, erythema multiforme and fixed drug eruption.
Table 1 : Causes of Blistering Diseases
(A) Subcorneal Blisters :
1. Bullous Impetigo
2. Subcorneal Pustular dermatosis
3. Miliaria Crystallina
(B) Intra-epidermal Blisters
1. Acute Dermatitis e.g. eczema, contact dermatitis
2. Pompholyx
3. Herpes infections
4. Fixed Drug eruptions (epidermal type)
5. Friction Blisters
6. Erythema multiforme (epidermal type )
7. Pemphigus Vulgaris
(C) Subepidermal Blisters
1. Bullous Pemphigoid
2. Linear IgA Diseases
3. Dermatitis Herpetiformis
4. Erythema Multiforme (dermal type)
5. Fixed Drug Eruptions (dermal type)
6. Epidermolysis Bullosa
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