Dermal hypersensitivity reaction: a PCR-confirmed pattern of herpetic dermatitis

Area of Science:

• Dermatology
• Virology
• Molecular Diagnostics

Background:

• Herpetic dermatitis from HSV and VZV often shows overlapping clinical and histopathologic features.
• Viral cytopathic changes are not consistently visible in biopsy specimens, complicating diagnosis.
• Distinguishing between HSV-1/2 and VZV can be challenging based on traditional methods alone.

Purpose of the Study:

• To evaluate the utility of polymerase chain reaction (PCR) in diagnosing herpetic dermatitis.
• To assess the correlation between clinical impression, histopathology, and PCR findings for HSV and VZV detection.
• To identify potential histopathologic mimics of herpetic dermatitis.

Main Methods:

• Retrospective review of 40 skin biopsy cases from 2004-2011.
• PCR analysis performed to detect herpes simplex virus types 1 and 2 (HSV-1/2) or varicella zoster virus (VZV).
• Correlation of PCR results with patient demographics, clinical diagnosis, and histopathologic features.

Main Results:

• Complete correlation between clinical, histopathologic, and PCR findings in 21 out of 40 cases.
• Discrepancies between clinical impression and histopathology were noted in 19 cases, with PCR confirming HSV or VZV infection in 15 of these.
• Three cases presented histopathologic features of dermal hypersensitivity reactions without detectable viral cytopathic changes.

Conclusions:

• Routine PCR testing for herpetic dermatitis is recommended when clinical suspicion of herpes virus infection exists, especially with non-specific histopathologic findings.
• PCR offers definitive diagnosis and differentiation between HSV and VZV.
• Dermal hypersensitivity reactions can represent a histopathologic manifestation of herpes virus infection ('herpes incognito').