Seborrheic keratosis (SK) is a benign epidermal
tumor of unknown etiology. Because of its
wart-like morphology, human papillomavirus (HPV) has been suggested as a possible causative agent. Viral involvement, however, has not been confirmed yet despite extensive research. The aim of this study was to evaluate the presence of HPV 6/11, 31, 33
DNA in nongenital SK. We analyzed 40 biopsy specimens taken from patients with nongenital SK using in situ polymerase chain reaction (PCR) and PCR with
tissue extracts. The SK specimens (n=40), analyzed by in situ PCR, were negative for all HPV probes tested (types 6/11, 31, 33). Control slides (condyloma acuminatum, n=3) were positive for type 6/11, 31, and 33 HPV probes tested.
Melasma samples (n=4), the negative controls, were consistently negative. No HPV
DNA band was detected by PCR with the
tissue extracts from
paraffin-embedded SK samples, while condyloma acuminatum, the positive controls, showed
DNA bands of the correct molecular weights. Our results show that HPV type 6/11, 31, and 33 cannot be recognized as causative agents for nongenital SK, which is in contrast to the previous studies. Further studies are required to reveal the presence of other types (more than 90) of HPV
DNA.