Kaposi Varicelliform Eruption

Etiology

Kaposi varicelliform eruption is primarily caused by herpes simplex virus type 1; however, other viral agents, such as herpes simplex virus type 2, coxsackie virus A16, vaccinia virus, varicella zoster virus, and variola virus (smallpox), have also been implicated in its pathogenesis.

Epidemiology

Kaposi varicelliform eruption is a rare condition first described in 1887 by Moritz Kaposi. This condition occurs more frequently in children due to its relationship with atopic dermatitis; however, adult cases are also reported. The incidence is not precisely known due to its rarity and the absence of a large case series.[8][9] The disease equally affects men and women and does not appear to have a specific ethnic predominance.

Pathophysiology

Kaposi varicelliform eruption was initially assumed to be secondary to a fungal infection. However, the finding of cytoplasmic inclusion bodies on histological examination suggests a viral origin. The mechanisms underlying the pathogenesis of viral reactivation in Kaposi varicelliform eruption remain incompletely understood. A defective skin barrier in conjunction with an immune deficiency contributes to the development of the disease. Both cell-mediated and humoral immunity dysfunction are implicated. In addition, cytokines released by type 2 helper T cells in atopic dermatitis also contribute.[10] Results from recent studies indicate a genetic contribution to the pathogenesis. Reports describe KVE occurring in sun-damaged or barrier-damaged skin, including peeling or injured areas.[11][12]

Histopathology

A skin biopsy is not required to confirm a diagnosis; however, if performed, histological findings may include intraepidermal blisters, acantholysis, multinucleated giant cells with intranuclear inclusions, and ballooning degeneration of keratinocytes.

History and Physical

Patients with Kaposi varicelliform eruption present with a sudden skin eruption of painful clusters of umbilicated vesicles and pustules. These vesiculopustules often evolve into crusted, hemorrhagic, punched-out skin erosions that may enlarge and coalesce into extensive denuded areas, susceptible to bacterial infection. The distribution of affected skin reflects skin barrier impairment since the eruption typically begins in areas of underlying dermatosis. This initial topographic distribution can delay diagnosis because the eruption is often mistaken for another condition. Kaposi varicelliform eruption may be associated with systemic symptoms, such as malaise, fever, and lymphadenopathy. In addition, the disease can be complicated by multiorgan involvement, mainly of the central nervous system, liver, lungs, gastrointestinal tract, and adrenal glands.

Evaluation

The diagnosis of Kaposi varicelliform eruption is primarily based on clinical examination, although several laboratory tests can be helpful.[13][14] A Tzanck smear, performed by scraping the floor of an opened vesicle and staining with Wright-Giemsa stain, may demonstrate multinucleated giant cells. The test is inexpensive, easily applicable, and rapid to perform. However, this method has low sensitivity and does not differentiate between herpes simplex virus types 1 and 2, or varicella-zoster virus.

Viral culture and direct fluorescent antibody staining on Tzanck smear are the most reliable techniques for herpes simplex virus detection. A skin biopsy or polymerase chain reaction may be performed in case of atypical, equivocal, or chronic lesions. Histological examination may confirm the diagnosis in uncertain cases, whereas the polymerase chain reaction detects viral DNA.

Treatment / Management

Treatment of Kaposi varicelliform eruption must be immediate since it is a potentially life-threatening disease. Antiviral therapy reduces morbidity and prevents complications. Nucleoside analogs are the antiviral agents most commonly used because they inhibit viral DNA replication.[15][16][17] Acyclovir is the most widely studied and prescribed drug for Kaposi varicelliform eruption. High-dose intravenous acyclovir is often necessary for disease control. The severity of the disease determines whether oral or intravenous treatment is required. The following dosing regimen is preferred:(B3)

• Oral acyclovir: 200 mg 5 times daily or 400 mg 3 times daily for mild to moderate disease
• Pediatric dosing: 40–80 mg/kg/day divided into 3–4 doses (maximum 1 g/day)
• Intravenous acyclovir: 10–15 mg/kg every 8 hours for severe or systemic disease

Most patients experience resolution of the skin lesions within several days. Prophylactic treatment with systemic antibiotics is recommended to prevent secondary bacterial infection.

Differential Diagnosis

 Kaposi varicelliform eruption may resemble several other skin conditions, including:

• Varicella (chickenpox)
• Impetigo
• Allergic contact dermatitis

Prognosis

Kaposi varicelliform eruption is a serious condition that could be fatal. The disease may occur as a primary or a recurrent infection. The primary form primarily affects children, is usually disseminated, and is associated with systemic symptoms and life-threatening complications such as bacterial sepsis, viremia, and multiorgan involvement. The recurrent form occurs in adults and is usually a milder, more localized form that generally presents without viremia. Septicemia from secondary bacterial infection of cutaneous lesions also increases morbidity and mortality.

The most common species isolated from patients with Kaposi varicelliform eruption are Staphylococcus aureus, group A β-hemolytic streptococcus, Peptostreptococcus, and Pseudomonas aeruginosa. Ocular disease can occur if herpes simplex virus–associated Kaposi varicelliform eruption affects the face. Ocular manifestations include uveitis, conjunctivitis, keratitis, and blepharitis. Herpetic keratitis is the most serious ophthalmological sequela, which may lead to vision loss from corneal scarring.

Complications

The principal cutaneous complications of Kaposi varicelliform eruption are secondary bacterial infections, most commonly due to Staphylococcus aureus or Streptococcus pyogenes. Such superinfections may evolve into cellulitis, abscess formation, or systemic bacteremia, increasing morbidity and prolonging the disease course. Extensive erosions and chronic ulceration often delay reepithelialization and may give rise to postinflammatory dyspigmentation and permanent scarring, particularly in cases of widespread involvement. Ocular complications represent an additional and clinically significant concern; periocular extension can precipitate herpetic keratoconjunctivitis, which, in the absence of urgent intervention, may culminate in irreversible visual impairment.

Systemic dissemination of herpes simplex virus in the context of KVE, although uncommon, is a life-threatening complication. Hematogenous spread may produce herpetic meningoencephalitis, fulminant hepatitis, or multiorgan failure, with mortality rates of up to 10% in untreated individuals. Patients at most significant risk include infants, immunocompromised hosts, and those with profound cutaneous barrier dysfunction, most notably in association with atopic dermatitis, pemphigus, or other blistering disorders. Importantly, even with appropriate systemic antiviral therapy, recurrent episodes may occur, especially among patients with uncontrolled inflammatory dermatoses or persistent immunosuppression.