Kaposi varicelliform eruption, also called eczema herpeticum, refers to a disseminated skin infection due to a virus that usually leads to localized vesicular eruptions, occurring in a patient with an underlying cutaneous disease. Although rare, it is potentially life-threatening disorder. Herpes simplex virus is considered the main causative agent.
The most commonly reported cases occur in patients with atopic dermatitis. However, it has been described in association with other skin conditions such as pemphigus foliaceus, ichthyosis vulgaris, bullous pemphigoid, Darier disease, Grover disease, Hailey-Hailey disease, dyskeratosis follicularis, mycosis fungoides, Sezary syndrome, psoriasis, pityriasis rubra pilaris, rosacea, seborrheic dermatitis, contact dermatitis (both allergic and irritant), second degree burns and skin grafts. Clinical features of Kaposi varicelliform eruption include widespread clusters of umbilicated vesicles and pustules that evolve into crusted skin erosions.
Kaposi varicelliform eruption is caused mainly by herpes simplex virus type 1; however, other viral agents such as herpes simplex virus type 2, Coxsackie A16, vaccinia, varicella zoster, and smallpox also have been involved in its pathogenesis.
Kaposi’s varicelliform eruption is a rare condition that was first described in 1887 by Moritz Kaposi. It occurs more frequently in children, probably due to its relationship with atopic dermatitis. However, adult cases have been reported. The incidence is not precisely known due to its rarity and the lack of large case series.
The disease equally affects men and women and does not appear to have a specific ethnic predominance.
Kaposi varicelliform eruption was initially assumed to be secondary to a fungal infection. However, the finding of cytoplasmic inclusion bodies in histological examination suggested a viral origin.
The mechanisms underlying the pathogenesis of viral reactivation in Kaposi varicelliform eruption remain incompletely understood. It is held that defective skin barrier acting in conjunction with immune deficiencies seems to lead to the development of the disease. Both cell-mediated and humoral immunity dysfunction are implicated. In addition, the Th-2 cytokine environment found in atopic dermatitis seems of crucial importance.
A number of recent studies suggest a genetic contribution to the pathogenesis of Kaposi varicelliform eruption.
A skin biopsy is not required to confirm a diagnosis, but if it is performed, histological findings include intra-epidermal blister, acantholysis, multinuclear giant cells with intranuclear inclusion, and ballooning degeneration of the keratinocytes.
Patients with Kaposi varicelliform eruption present with a sudden skin eruption of painful clusters of umbilicated vesicles and pustules. Vesiculopustules often evolve into crusted, hemorrhagic, and punched-out skin erosions that may enlarge and coalesce to form extensive denuded areas which are more likely to get a bacterial infection.
The distribution of affected skin reflects the crucial role of skin barrier impairment since Kaposi varicelliform eruption begins in areas of underlying dermatosis. This inaugural topographic distribution may lead to a delayed diagnosis because the eruption is often confused with the pre-existing condition.
Kaposi varicelliform eruption may be associated with systemic symptoms such as malaise, high temperature, and swollen lymph nodes. In addition, the disease can be complicated by multiple organ involvements, mainly of the central nervous system, liver, lungs, gastrointestinal tract, and adrenal glands.
The diagnosis of Kaposi varicelliform eruption is mainly made on the basis of a clinical examination although several laboratory tests can be helpful.
A Tzanck smear is performed by scraping the floor of an opened vesicle and staining the material with Wright-Giemsa stain which will demonstrate multinucleated giant cells. It is inexpensive, easily applicable, and quick to perform. However, this method suffers from low sensitivity and does not differentiate between herpes simplex virus 1 and 2, or between herpes simplex virus and varicella-zoster virus.
Viral culture and direct fluorescence antibody staining on Tzanck smear are the most reliable techniques for herpes simplex virus detection.
In case of atypical, equivocal, or old lesions, a skin biopsy or polymerase chain reaction may be performed. In fact, a histological examination may confirm a diagnosis that may not have been thought of clinically, whereas polymerase chain reaction will detect viral DNA by Polymerase Chain Reaction.
Treatment of Kaposi varicelliform eruption must be instituted with no delay since it is a potentially life-threatening disease. Antiviral therapy is effective in reducing morbidity and preventing complications. Nucleoside analogs are the antiviral agents most commonly used since they inhibit viral DNA replication.
Acyclovir is the most widely studied and prescribed drug for of Kaposi varicelliform eruption. High dose intravenous acyclovir is often necessary for disease control. Most patients achieve resolution of the skin lesions over several days. Prophylactic treatment with systemic antibiotics is recommended to prevent secondary bacterial infection.
Kaposi varicelliform eruption may be confused with various conditions:
Kaposi varicelliform eruption is a serious condition that may have fatal outcomes.
The disease may occur as a primary or a recurrent type of infection. The primary form mainly concerns children and is usually disseminated and associated with systemic symptoms and life-threatening complications such as bacterial sepsis, viremia, and multiple organ involvements. The recurrent type occurs in adulthood and is usually a milder and more localized form, generally presenting without viremia.
Septicemia resulting from secondary bacterial infection of cutaneous lesions also increases the morbidity and the mortality The most common species isolated from patients with Kaposi varicelliform eruption are Staphylococcus aureus, group A beta-hemolytic streptococcus, Peptostreptococcus and Pseudomonas aeruginosa.
Risk of ocular involvement exists when herpes simplex virus-associated Kaposi varicelliform eruption affects the face. Ocular anomalies include uveitis, conjunctivitis, keratitis, and blepharitis. The most serious ophthalmological sequela is herpetic keratitis which may lead to vision loss resulting from corneal scarring.
Kaposi varicelliform eruption should be diagnosed accurately since it may have fulminant outcomes. Although there is no consensual therapeutic approach, the early use of antiviral therapy in association with systemic antibiotics is crucial.