Seborrheic keratosis: clinical characteristics and an association with the β-genus human papillomavirus

Background: Seborrheic keratosis is a  common benign tumor of unclear etiology. Aim: To study associations between clinical characteristics of seborrheic keratosis and its course with quantitative parameters of the β-genus human papillomavirus (β-HPV). Materials and methods: The main study group included 91 patients with seborrheic keratosis (29 male and 62 female), aged 40 to 75  years (mean ± SD, 59.2 ± 6.4 years). The control group included 30 healthy individuals persons aged 40 to 70 years (mean 57.6 ± 4.1 years). The diagnosis of seborrheic keratosis was confirmed by dermoscopy and pathomorphological assessment, with 100% of patients having the acanthotic type of seborrheic keratosis. HPV was identified by polymerase chain reaction with hybridization fluorescent detection in real time mode with use of three oligonucleotide systems for detection of HPV genus β1 (subtypes 5, 8, 12, 14, 19, 21, 25, 36, 47); β2 (subtypes 9, 15, 17, 22, 23, 37, 38, 80), and β3 (subtypes 49, 75, 76). Results: The most frequent clinical type of seborrheic keratosis was the maculopapular one (61/91 patients, 67%) localized mainly on head, neck, anterior and posterior trunk. β-HPV was found in 88.8% biopsy samples taken from the seborrheic keratosis areas in 24 of 27 patients and in 66.6% biopsy samples taken from the normal skin areas of the same patients (р = 0.04). This is significantly more frequent that the HPV contamination among healthy individuals, which was 28.7% (р = 0.02). Mixed association of β-HPV was also more frequent in the HPV-positive patients (21/24, or 83.3%; compared to the control group, р = 0,00001). The maximal (significant) viral load was found in the subgroup of seborrheic keratosis patients with the number of proliferative lesions of 10 and more (4.08 ± 0.3 lg/105 tо 5.7 ± 0,3 lg/105). Conclusion: The maculopapular type of seborrheic keratosis is characterized by mixed HPV β1, β2, β3 infection found in 77.7% of cases irrespective of the number of proliferative lesions. It could be hypothesized that multiple seborrheic keratosis (more than 10 lesions) develops in simultaneous presence of HPV β1, β2, β3 and is associated with a  higher probability of new seborrheic keratosis lesions on intact skin.