A pink papule on the back of an 82-year-old man: an example of the buttonhole sign on reflectance confocal microscopy - Syril Keena T. Que; Naiara Fraga-Braghiroli; Jane M. Grant-Kels; Harold S. Rabinovitz; Margaret Oliviero; Alon Scope (Mattioli1885, 2016)