The researchers are doing this study to see if giving people fluorescein sodium as an IV infusion before their vulvectomy for treating extramammary Paget's disease (EMPD) can help surgeons with performing the procedure. The researchers will look at whether fluorescein sodium helps surgeons identify disease cells that should be removed. Other purposes of this study include looking at the following: If there are any complications during or after vulvectomy involving the use of fluorescein sodium. If fluorescein sodium can reveal tissue that surgeons cannot operate on (unresectable tissue).