Original sentence: Nottingham University Clinical Trials Unit(CTU) is currently running a large research study in around 50 hospitals throughout the UK and Ireland to investigate the best way of treating the rare skin disease, pyoderma gangrenosum.STOP GAP stands for ‘Study of Treatments for Pyoderma Gangrenosum patients’.The first hospital was opened to recruiting patients in May 2009.The website for further information on enrolling into the trial is.There are two parts to this study:.We want to do this as these treatments have never been properly studied before and doctors are confused about the best treatment to give.•The observational part: If your dermatologist feels that you would benefit from being treated with a cream, which is known as ‘topical therapy’, they are still interested in seeing you.•The randomised part: they are comparing the two most commonly used medicines for the treatment of pyoderma gangrenosum