Virologic safety of polyvinyl chloride film in dermoscopic analysis of mucosal areas

Background: Increasing evidence supports the diagnostic accuracy of epiluminescence microscopy in non-invasive diagnosis of mucosal pigmented lesions. In particular, dermoscopy may play a relevant role in the preoperative assessment of suspicious lesions, providing morphologic criteria for the differentiation of melanoma from other melanocytic and nonmelanocytic mucosal pigmented lesions. The need to avoid transmission of infectious agents, is a requirement of primary importance in routine dermoscopic examination of mucosal sites. Objective: To evaluate the adequacy of disposable protective material to prevent probe contamination during dermoscopic observation of mucosal surfaces, a PVC film usually employed in packaging foodstuffs was tested. Design: PCR assay to evaluate barrier effectiveness of PVC film in preventing diffusion of viruses. Intervention: An experimental system was set up to verify whether PVC film is effective in preventing diffusion of virus particles during an incubation time comparable to that needed for the dermoscopic examination. To this purpose, increasing concentrations of HSV-2 and HIV-1 suspended in sterile solution were placed on one side of the membrane and incubated in sterile conditions for up to 30 min at room temperature. Virus diffusion through the membrane was evaluated by PCR and rtPCR. The investigation was performed on PVC samples both in pre-use conditions and in controlled, simulated clinical use conditions. Setting: Department of Clinical and Experimental Medicine, Section of Dermatology, Department of Experimental and Diagnostic Medicine, Section of Microbiology, University of Ferrara. Main outcome measures: The lack of viral sequences on the unexposed side of the membrane indicated that PVC efficiently prevents virus diffusion. Results: PVC film prevented the diffusion of HSV-2 and HIV-1 for virus concentrations up to 107 copies/ml (corresponding to about 105 PFU for HSV-2 and 105 TCID50 for HIV-1), which are 100-fold higher than those found in biologic fluid of patients with asymptomatic infection. No differences were observed between membranes in pre-use conditions and in simulated clinical use conditions. Conclusions: our findings show PVC film effectiveness in preventing viral diffusion and suggest its safety to ensure probe uncontamination during dermoscopic observation. The interposition of PVC film allows an unmodified view of the pigmented lesions in comparison with the standard procedure, as previously reported1. The application of a PVC film to cover the probe surface is proposed as a safe and efficient disposable barrier in routine dermoscopic observations of mucosal sites.