Diagnosis of Cutaneous Herpesvirus Infections from Paraffin-Embedded Tissue Using PCR
G Turner, K Pesavento, C Sutherland, KL Kaul, TA Victor. Evanston Northwestern Healthcare, Evanston, IL
Background: Both primary and reactivated Herpes-family virus infection can result in cutaneous lesions. Knowledge of which Herpesvirus is causing clinical symptoms can be important in immediate and long-term treatment. It is impossible to differentiate between lesions caused by Herpes Simplex Virus 1 (HSV-1), Herpes Simplex Virus 2 (HSV-2) and Varicella Zoster Virus (VZV) via routine H&E light microscopy. Although IHC stains for HSV-1/HSV-2 and VZV are commercially available, they have shown limited usefulness in our IHC lab. Real-time PCR assays for the detection and differentiation of these viruses have become widely available. This study examines the ability of PCR to detect and discriminate various Herpesvirus family members in paraffin-embedded skin lesions.
Design: Paraffin-embedded tissue blocks for 23 skin biopsy specimens with Herpes Virus in the diagnosis text were retrieved. Of these, 13 were clinically suspect for Herpesvirus infection, 21 were diagnosed histopathologically as Herpesvirus infection (VZV or HSV) or consistent with Herpesvirus infection, and 2 were diagnosed as possible Herpesvirus infection. Sections from each were stained with antibody against HSV-1/HSV-2 (Ventana Medical Systems, #760-2648) and against VZV (Novocastra, clone C90.2.8). DNA was extracted from paraffin-embedded tissue and analyzed by real-time PCR for HSV-1/HSV-2 and VZV using commercial and in-house-developed ASR reagents, respectively.
Results: Of the 23 specimens, IHC and PCR were in agreement for 12 cases. 7 were HSV positive/VZV negative by both IHC and PCR. 3 were VSV positive/HSV negative by both approaches and 2 cases were entirely negative. Among the cases with discrepant results, 1 was positive for HSV by PCR but not IHC. 6 were positive for VZV by PCR but not by IHC. 4 cases demonstrated mixed positivity for HSV and VZV by IHC and/or PCR.
Conclusions: Real-time PCR performs similarly to IHC in the detection of HSV in formalin-fixed paraffin-embedded skin biopsy specimens. Real-time PCR appears to be more sensitive than IHC in the detection of VZV. Several specimens demonstrated the unexpected finding of mixed positivity by both IHC and PCR. Real-time PCR can serve as an important tool in the identification of Herpesvirus family members from paraffin-embedded tissue.
Wednesday, March 11, 2009 1:00 PM
Poster Session VI # 224, Wednesday Afternoon