Aims: To determine the presence or absence of human papillomavirus (HPV) DNA in oral inverted ductal papillomas (IDPs) using in situ hybridisation (ISH), and to analyse all cases for histological features of HPV infection.
Methods: Six cases were retrieved from archival material and paraffin wax blocks were submitted for the detection of HPV DNA by means of ISH. A wide spectrum probe for HPV subtypes 6, 11, 16, 18, 31, 33, 45, 51, and 52 was used initially. Cases that were positive using this wide spectrum probe were further subtyped using HPV type specific probes (6/11, 16/18, and 31/33). The histological features of all tumours were analysed using routine microscopy.
Results: Of the six cases of oral IDP identified, three were positive for HPV subtypes 6/11. All positive cases showed histological features of HPV infection (koilocytosis, papillomatosis, binucleated keratinocytes, and abnormal mitosis) in both the surface and the inverted epithelium. The three cases that tested negative for HPV DNA also exhibited focal histological features of HPV infection (two in the surface epithelium and one in the endophytic epithelium).
Conclusions: These are the first documented cases of oral IDP to demonstrate positivity for HPV DNA and also to show histological features of HPV infection.