Kaposi's Varicelliform Eruption in a Child with Atopic Dermatitis: A Case Report.

Background and Clinical Significance: Eczema herpeticum (EH), or Kaposi's varicelliform eruption, is a dermatologic emergency characterized by the abrupt onset of painful monomorphic vesiculopustules with potential for rapid dissemination. Atopic dermatitis (AD) is the main predisposing condition due to skin barrier dysfunction and impaired antiviral immunity. Early recognition is essential because delayed treatment may result in avoidable complications, including ocular involvement and systemic disease. Current recommendations emphasize immediate systemic acyclovir based on clinical suspicion, without awaiting laboratory confirmation. Case Presentation: A 4-year-old boy with moderate AD presented with a 6-day history of fever, malaise, and a rapidly progressive vesiculopustular eruption involving both eczematous and previously unaffected skin. The patient had a recent AD flare, molluscum contagiosum, and had initially received oral amoxicillin-clavulanate for presumed bacterial superinfection without improvement. Physical examination revealed widespread painful monomorphic umbilicated vesiculopustules with hemorrhagic crusts and mild bilateral conjunctival injection. Oral acyclovir was initiated within one hour of evaluation. Laboratory investigations showed mild inflammatory abnormalities without renal or hepatic involvement. Because lesional PCR was unavailable, complementary blood-based investigations were performed; HSV-1 IgM serology and blood PCR provided additional retrospective findings compatible with HSV-1 infection, while Gram stain and bacterial cultures were negative. Fever resolved within 24 h, no new lesions developed after day 3, and complete re-epithelialization was achieved after a 10-day course of acyclovir. Conclusions: This case highlights the importance of bedside recognition of eczema herpeticum in children with atopic dermatitis, particularly when painful monomorphic vesiculopustules are accompanied by fever and rapid dissemination. Early initiation of systemic acyclovir based on clinical suspicion remains the cornerstone of management. While PCR from vesicular lesions is the preferred diagnostic test when available, laboratory confirmation should not delay treatment. This report also illustrates common real-world challenges, including initial misdiagnosis as bacterial infection and limited access to optimal virological testing.