Evaluation for HPV in VX has been studied and has included types 6, 7, 11, 12, 16 to 19, 31, 33, 35, 37, 44 to 47, 53, 54, and 58.6,13,21- 23 While most studies failed to show evidence of HPV, 1 study13 demonstrated by immunohistochemical analysis a positive reaction in the upper epidermal keratinocytes, which was confirmed by electron microscopy and by PCR, which also detected HPV-DNA 6a. Another investigation22 demonstrated by immunohistochemical analysis a positive reaction with polyclonal antisera against papilloma virus. This reaction was observed in histiocytes and could not be confirmed by in situ hybridization. Thus, the authors concluded that this reaction could be the result of cross-reactivity to HPV-unrelated antigens. One more positive reaction in histiocytes with HPV antisera,6 which could not be confirmed by electron microscopy, has also been reported. Similarly, Iamaroon and Vickers21 demonstrated a positive reaction with anti-HPV antibodies by in situ hybridization in 1 of 12 cases. However, this study also failed to confirm the positive reaction by immunohistochemical analysis. Thus, so far no conclusive viral etiology has been found.