Abstract: Objective To evaluate the infection rate of HPV in keratoacanthoma(KA)patients, and to observe the distribution of HPV DNA positive cells in KA tissues.Methods Tissue specimens were resected during operation from 26 KA patients(diagnosed with clinical and histopathological manifestadons)and 26 normal controls, then embedded in paraffin and subjected to in situ hybridization (ISH) for the examination of HPV DNA.Results HPV DNA was detected in 10(38.46%, 10/26)patients, but not in any of the controls, with a significant difference between the two groups in the detection rate(P<0.01).Of the 10 patients positive for: HPV DNA, 9 presented with lesions of mature stage, and 1 with lesions of regressive stage, as shown by the histopathological examination.HPV DNA positive cells were predominately located in the hyperplastic stratum spinosum under crater-shaped epidermal depression, and most of the cells aggregated together.The differences were of no statistical significance in gender, onset age, disease duration or tumor size between HPV DN,A negative and positive patients(all P >0.05).Conclusions Compared with the normal population, KA patients have a higher infection rate of HPV, and the infection appears to be unrelated to the age, gender, disease duration or tumor size of these patients.

Key words: Keratoacanthoma, Papillomavirus, human, In situ hybridization