Given a nested merchandise catalog dictionary, extract attributes for a specific item and traverse related items recursively to build the full relationship tree.

Focus on demonstrating your understanding of data structures, particularly dictionaries and recursion. Start by clearly defining the structure of the nested merchandise catalog and the specific item you need to extract. Then, outline your approach to traverse the catalog recursively, ensuring you explain how you will handle related items and maintain the relationship tree. Be prepared to discuss edge cases, such as items with no related products or circular references, and how your solution will address these scenarios. Finally, consider the efficiency of your algorithm and any potential optimizations you might implement.