Koebnerization of reactive perforating collagenosis induced by laser hair removal.

Laser hair removal, due to demonstrated efficacy and safety, has become a commonly performed office procedure. We report an unusual occurrence after laser hair removal with the 800 nm diode laser that previously has never been described. After laser hair removal treatment to the ventral surface of the ears, a patient developed lesions of previously diagnosed reactive perforating collagenosis. Interestingly, the lesions appeared on the dorsal surface of the ears. Perhaps the koebner phenomenon was invoked as the laser energy penetrated to the untreated dorsal surface, which was not protected by epidermal contact cooling.