Chapter 11 Pustular eruptions
1. How does a pustule differ from a vesicle or bulla?
A pustule is a purulent vesicle or bulla. Whereas a vesicle contains clear or translucent fluid, a pustule is filled with neutrophils or, less commonly, eosinophils. Pustules are one of the primary lesions in skin. Most pustular eruptions begin as pustules, but others may pass through a transitory stage in which they appear vesicular (vesiculopustules).
2. How are pustules classified?
Pustules may be classified on the basis of where the acute inflammatory cells accumulate (e.g., subcorneal, follicular), pathogenesis (e.g., infectious, autoimmune), predominant inflammatory cells (e.g., neutrophils, eosinophils), and clinical presentation (Table 11-1). Pustules may be unilocular or multilocular.
3. What is the most common pustular skin eruption?
Acne vulgaris, although not all lesions in this condition are pustular (Fig. 11-1). The infectious pustular eruptions are also common (see Chapter 27).
4. Name the different types of pustular psoriasis. How do they differ?
Pustular psoriasis may be broadly subdivided into localized and generalized forms. Localized pustular psoriasis may occur on any site and may also occur within plaques of classic psoriasis. Distinctive variants include acrodermatitis continua of Hallopeau (Fig. 11-2A), which is characterized by pustules and crusting of the distal fingers and toes, and localized pustular psoriasis of the palms and soles (Fig. 11-2B). It is unclear whether pustular eruptions confined to the palms and soles represent a form of localized psoriasis or a different disease called pustular bacterid. Variants of generalized pustular psoriasis include generalized pustular psoriasis of von Zumbusch, exanthematic generalized pustular psoriasis, and impetigo herpetiformis. The von Zumbusch variant presents as generalized pustules in patients with preexisting plaque-type psoriasis or erythrodermic psoriasis. Exanthematic generalized pustular psoriasis arises suddenly without preceding psoriasis (Fig. 11-2C). Impetigo herpetiformis is associated with pregnancy. Hypocalcemia is also frequently present.
5. Do any factors precipitate generalized pustular psoriasis?
The most important inciting factor is the administration of systemic corticosteroids. In a study of 104 patients, corticosteroids were implicated as the precipitating factor in 37 patients (36%). This association is one of the primary reasons that psoriasis is not treated with systemic corticosteroids. Less common precipitating factors included infection (13%), hypocalcemia (9%), pregnancy (3%), and other drugs (e.g., terbinafine).
| PATHOGENESIS | SITE OF ACCUMULATION |
|---|---|
| Autoimmune | |
| IgA pemphigus | Subcorneal |
| Infectious | |
| Arthropod reactions | Intraepidermal |
| Candidiasis | Subcorneal |
| Furuncle/carbuncle | Follicular |
| Impetigo | Subcorneal |
| Hot tub (pseudomonal) folliculitis | Follicular |
| Kerion (tinea capitis) | Follicular |
| Pityrosporum folliculitis | Follicular |
| Vaccinia infection/vaccination | Intraepidermal |
| Inherited | |
| Pustular psoriasis | Subcorneal, intraepidermal |
| Reiter’s syndrome | Subcorneal, intraepidermal |
| Drug eruptions | |
| Acneiform drug-induced eruptions | Follicular |
| Toxic erythema with pustules | Subcorneal |
| Halogenodermas | Intraepidermal |
| Miscellaneous | |
| Acne necrotica miliaris | Follicular |
| Acne vulgaris | Follicular |
| Erythema toxicum neonatorum | Follicular |
| Folliculitis decalvans | Follicular |
| Infantile acropustulosis | Subcorneal, intraepidermal |
| Miliaria pustulosa | Sweat duct |
| Pustular bacterid | Intraepidermal |
| Rosacea | Follicular |
| Subcorneal pustular dermatosis | Subcorneal |
| Transient neonatal pustular dermatosis | Subcorneal |
Figure 11-1. Gram-negative pustular acne vulgaris.
(Courtesy of the Fitzsimons Army Medical Center teaching files.)
6. Is pustular psoriasis treated differently than classic plaque-type psoriasis?
Most treatments that are used on classic plaque-type psoriasis can also be used for the management of pustular psoriasis. The retinoids, especially acitretin, are particularly effective in pustular psoriasis and are the treatment of choice for generalized pustular psoriasis. More recently, isolated cases have been successfully treated with topical biologic agents such as tacrolimus or parental biologic agents such as infliximab and adalimumab.
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