In the past few years virtual reality based systems have been proposed and realized for many medical interventions. These simulators have the potential to provide training on a wide variety of pathologies. So far, realistic generation of anatomical variance and pathologies have not been treated as a specific issue. We report on a cellular automaton, specially developed to generate macroscopic findings fulfilling the requirements for a sophisticated simulation. The specific pathology investigated are leiomyomas protruding to different extents into the uterine cavity. The automaton presented is part of a virtual reality based hysteroscopy simulator which is currently under development.