Dietrich Doll1,2, Sven Petersen3. 1. Chris Hani Baragwanath Hospital, University of the Witwatersrand, Johannesburg, South Africa. ddoll@gmx.de. 2. Department of Surgery, Army Hospital, Berlin, Germany. ddoll@gmx.de. 3. Department of Surgery, Bethesda General Hospital, Hamburg Bergedorf, Germany.