The coordinated consideration of diverse perspectives and knowledge sources in medical decision-making contexts is undoubtedly of crucial importance, in that it augments the quality of both the overall process and decisions to be made. Towards this end, this study presents a web-based system that aims at the exploitation of personalized knowledge through a structured process of collaborative and argumentative resolution of issues raised in such settings. By using the system, a consensus emerges through the process of collaboratively considering alternative interpretations of the issue under consideration. Using an illustrative example of collaboration between a group of experts deciding on the most appropriate treatment for a particular case of breast cancer, we present the design rationale, features and functionality of the proposed system. Much attention is also paid to the associated knowledge management issues. The system can be used for distributed, asynchronous collaboration, allowing users to surpass the requirements of working at the same place and time.