Identification of human papillomavirus in keratoacanthomas

Background: Keratoacanthomas are benign, clinically distinct skin tumors that may infiltrate and show cellular atypia. A viral etiology has been suggested, and the aim was to search for human papillomavirus (HPV) in keratoacanthomas. Methods: From 21 immunosuppressed organ transplant recipients and 11 non-immunosuppressed patients, 72 fresh biopsies with diagnosis of keratoacanthomas were analyzed. For detection of cutaneous and genital HPV DNA, single-tube nested 'hanging droplet' polymerase chain reaction (PCR) and another PCR (GP5(+) and 6(+)) were used, respectively. Results: Among 21 immunosuppressed patients, 71% (15/21) harbored HPV DNA at least in one sample. Of the keratoacanthoma lesions, 55% (33/60) were HPV DNA positive. Fourteen samples from eight immunosuppressed patients contained HPV types 5, 9, 10, 14, 19, 20, 21, 38, 49, 80, putative HPV types as HPVvs20-4, HPVvs75, and HPVvs92 and FA16.1, FA23.2, FA37, FA75, and FA81. Among 11 non-immunosuppressed patients, 36% (4/11) harbored HPV DNA at least in one sample, and 33% (4/12) of their keratoacanthomas were HPV DNA positive. In total, HPV DNA was detected in 51% (37/72) of the keratoacanthomas. Conclusions: By the use of PCR, cutaneous HPV DNA was detected in 51% (37/72) of the keratoacanthomas. No predominating HPV type or genital HPV type was identified. The role of HPV in keratoacanthomas remains thus elusive.