“…Several features are known to be associated with the infection, including dyskeratosis, parakeratosis, bi-and multinucleation and the presence of koilocytes. Of these, koilocytosis is the only truly diagnostic feature, and although we know from Morse et al 15 that by relying on the presence of koilocytes only the infection will be underdiagnosed, the obverse is also true and reliance on other factors leads to overdiagnosis. In our department we use koilocytosis alone as a criterion of active wart virus infection using criteria laid down by Meisels 13,14 .…”