Virtual reality based surgical simulators offer the possibility to provide training on a wide range of findings of different pathologies. Current research aims at a high fidelity hysteroscopy simulator. Different methods for the generation of pathologies have been investigated to realize the first surgical simulator that challenges the trainee with a new scene in every training session. In this paper, a particles-based tumor growth model is presented that overcomes different limitations of previous approaches. It allows for a realistic generation of both polyps and myomas protruding to different extents into the uterine cavity. The model incorporates several biological as well as mechanical factors, which influence the growth process and thus the appearance of the pathologies.