White : Diseases of the Skin - Eczema and Related Disorders

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Gary M. White & Neil H. Cox

Diseases of the Skin

6	Eczema and Related Disorders

ECZEMA HERPETICUM

Etiology and pathogenesis

This widespread infection by herpes simplex, previously called Kaposi varicelliform eruption, is most common in patients with AD but may also occur in patients with other forms of dermatitis (including seborrheic, neuro-, and photosensitivity dermatitis), as well as in Darier disease, pemphigus foliaceus, CTCL, benign familial pemphigus, second-degree burns, and congenital ichthyosiform erythroderma. Ocular involvement (as evidenced by slit-lamp examination) is uncommon, even though there may be a concentration of lesions periorbitally and a conjuctival swab may be positive (Fig.6.18). Kaposi varicelliform eruption has occurred rarely in atopic patients secondary to cowpox infection.

Clinical

Any age group can be affected. The rapidly progressive, widespread, crusted papules, vesicles, and erosions are characteristic (Fig.6.19). Monomorphic ‘punched out’ lesions are very suggestive of this diagnosis. Secondary bacterial infection

Table 6.4 SOME CAUSES OF ACQUIRED ICHTHYOSIS

Category	Cause
Mechanical or irritant	See this chapter’s section on Xerosis
Endocrine, metabolic and deﬁciency diseases	Hypothyroidism, hyperparathyroidism, chronic renal failure, malnutrition generally and specific (e.g. essential fatty acid deﬁciency, niacin deﬁciency)
Malignancy	Especially systemic lymphomas, also mycosis fungoides, various cancers
Infections	HIV, human T-cell leukemia virus (HTLV)-I, leprosy, tuberculosis
Drugs	Hydroxymethylglutaryl-CoA reductase inhibitors (statins), retinoids
Inflammatory and autoimmune	Sarcoidosis, systemic lupus erythematosus, graft-versus-host disease


Figure. 6.23 Xerosis and scratching. An atopic background; dry, cold weather; frequent water contact; advanced age; and irritants predispose to dry skin, also known as xerosis. Dry skin itches, as illustrated by the scratch marks here.

may occur (Fig.6.20). Many patients with AD will present with crusted lesions, and the etiology (viral versus staphylococcal) is impossible to determine without a culture (Fig.6.21). Thus both viral and bacterial cultures are essential when vesicles (Fig.6.22) are not apparent.

Differential diagnosis

Superinfection of AD by S. aureus can appear very similar, with


Figure. 6.24 Diffuse asteatotic eczema. The older patient is commonly affected during the winter.

Figure 6.25 Asteatotic eczema. (a) An eczematous dermatitis on the posterior axillary line is not uncommon. (b) Close-up view.

Figure 6.26 Eczema craquéle. At times, the ﬁssures are quite red and prominent, giving a cracked appearance to the skin, much like some porcelain vases.

Figure. 6.27 Eczema of the leg, with purpuric changes. Some degree of purpura is common in eczema of the lower leg, especially if the onset is acute, if the patient is elderly, or if there is associated swelling of the leg.

the acute onset of crusting, eroded skin. However, the monomorphous, circular vesicles that are commonly seen in eczema herpeticum are absent, although the later punched out lesions can occasionally occur with primary staphylococcal infection or even in very acute eczema.

Treatment

Oral or intravenous aciclovir, or a related antiviral agent, should be given. Twice-daily soaks can be helpful for removing crust. A topical antiseptic or antibiotic ointment may also help speed healing.

PRACTICE POINTS

• If you get a phone message saying that one of your patients is experiencing a signiﬁcant flare of his or her eczema, especially if around the head and neck or accompanied by systemic symptoms, see them urgently: it may be eczema herpeticum. The authors make no apology for repeating this point.