Demonstration of human papillomavirus 60 in the palmoplantar epidermal cysts

Background: It is generally accepted that the most spontaneously-arising epidermal cysts might be related to follicular infundibulum and palmoplantar epidermal cyst (PPEC) has been suggested to be caused from traumatic implantation of epidermal fragments. In addition there were several recent reports of human papillomavirus (HPV) implicating in formation of PPEC and also similar reports in Korean dermatologic literature. But the latter failed to reveal the presence of HPV in PPEC or a specific type of HPV by molecular biologic methods. Objective: We tried to identify the presence of HPV and its subtype in PPEC. Methods: After reviewing routine histopathologic findings recalling HPV infection in 8 PPECS, we undertook immunohistochemistry using polyclonal HPV antibody and polymerase chain reactions with 3 sets of HPV primers. To confirm the actual location of HPV in cyst in situ hybridization with HPV 60 probe was also done. Results: All cases showed more than one feature of HPV infection. The positive reactions were 3 out of 8 on immunohistochemistry and 5 out of 8 on polymerase chain reaction. All cases (4 of 4) were positive on in situ hybridization and they were found in the horny layer and/or wall of cysts. Conclusion: PPEC in Korea may show similar typical histopathologic features with those reported in Japan. The HPV were detected in almost PPEC by molecular methods and their subtype was all HPV 60.