White : Diseases of the Skin - Blistering Disorders

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Gary M. White & Neil H. Cox

Diseases of the Skin

16	Blistering Disorders

INFLAMMATORY CAUSES OF BLISTERING

Eczemas and related disorders

Eczemas often cause vesicles or frank blisters, especially the pompholyx pattern on the hands and feet (Ch.6). Blistering in eczema is sometimes due to secondary infection, in which case there is usually a cloudy fluid content (Fig.16.11). Acute allergic contact eczemas also tend to cause blistering, particularly the types due to plants (Fig.16.12). Many other inflammatory dermatoses may occasionally cause blistering (Fig.16.13).

Phototoxic reactions (Fig.16.14) due to psoralens in plants and fruits are a cause of blistering that often leaves residual pigmentation. This is discussed further in Chapter 17.

Erythema multiforme and Stevens–Johnson syndrome

These conditions are discussed in more detail in Chapter 11. Erythema multiforme produces skin lesions; Stevens–Johnson syndrome also affects mucous membranes (Fig.16.15).

Figure 16.12 Contact allergy. (a) Contact allergy appearing on the forearm. Blistering is unusual in endogenous eczema at this site. (b) Allergy to an ivy plant. The lesions are often linear in shape, as the limb has brushed against the culprit foliage.

Figure 16.13 Bullous lichen sclerosus is very unusual. It may cause significant scarring, as shown here with a large blister on the posterior scalp.

Figure 16.14 Phototoxic blistering affecting the hand of a child. Such cases are often due to fruit juices, such as lemon or lime, or from contact with common hedgerow plants of the Umbelliferae family. (Courtesy of Dr. W. D. Paterson.)

Figure 16.15 Stevens–Johnson syndrome, showing mucosal blistering and crusting (see also Ch. 11). (Courtesy of Dr. G. Dawn.)

Drugs

Drugs may cause blistering of several types (Table 16.2; see also Ch.18). The most severe is toxic epidermal necrolysis (Fig.16.16).

Subcorneal pustular dermatosis (Sneddon–Wilkinson disease)

Etiology and pathogenesis

Most cases are of unknown etiology, but a significant minority have an underlying monoclonal gammopathy (usually IgA type) or myeloma.

Clinical

Most patients are adult, and there is a female predominance. The lesions are bullous or pustular, and may consist of clear fluid with a ‘pus level' as occurs also in bullous pemphigoid (Fig.16.17). In subcorneal pustular dermatosis, they are often grouped lesions with an annular polycyclic arrangement (Fig.16.18). The trunk and flexures are the main sites. Biopsy shows an extremely superficial (subcorneal) pustule with neutrophil content; some cases have positive intercellular direct immunofluorescence for IgA. Pyoderma gangrenosum may occasionally coexist, usually, but not invariably, in patients with a paraproteinemia.

Differential diagnosis

The blisters in this condition may resemble those of pemphigoid or of impetigo, although other bullous eruptions may also be considered.

Table 16.2 DIFFERENT MECHANISMS OR PATTERNS OF DRUG ERUPTION THAT MAY CAUSE BLISTERS

Mechanism or pattern	Comments
Fixed drug eruption	Usually solitary, localized; may be bullous, heal with pigmentation
Erythema multiforme or toxic epidermal necrolysis	Associated with isolated or semiconfluent background inflammation; see Chapter 18 for likely causes (also Fig.16.15)
Photosensitivity	Blisters on a background of eczematous rash in photosensitive distribution
Porphyria and pseudoporphyria	Porphyria cutanea tarda (PCT) pattern of blisters and skin fragility, mainly hands and face; PCT may be provoked by estrogens, pseudoporphyria especially by furosemide and naproxen
Blistering at pressure areas	Classically due to barbiturate-induced coma
Eruptions that resemble idiopathic immunobullous disorders	Some are provocation of immunobullous disease (e.g. penicillamine-induced pemphigus, vancomycin-induced linear IgA disease, progesterone dermatitis), others are non-specific or resemble patterns (see also Ch.18)

Figure 16.16 Toxic epidermal necrolysis. The fragile sheared blisters and resulting erosions cannot be distinguished clinically from staphylococcal scalded skin syndrome, but the level of blister splitting is different and most cases of toxic epidermal necrolysis are in adults.

Figure 16.17 This blister shows a clear fluid component above a ‘pus level’ determined by gravity, in this instance in a case of bullous pemphigoid. This may also occur in subcorneal pustular dermatosis and in impetigo.

Figure 16.18 Subcorneal pustular dermatosis, demonstrating typical grouped crusting and large pustules. Pemphigoid may be considered clinically, but biopsy shows an extremely superficial (subcorneal) pustule with neutrophil content. (Courtesy of Gary W. Cole, M.D.)

Treatment

The disorder usually responds to sulfones such as dapsone (see Ch.4). Any associated gammopathy must also be treated. Phototherapy has also been used.

Other disorders

Many other disorders can on occasion cause pustules, vesicles, or bullae, but are described in other chapters. For example, fungal infections (especially of the foot) may cause blisters.