DDxTutor: Clinical Reasoning Tutoring System with Differential Diagnosis-Based Structured Reasoning

Clinical diagnosis education requires students to master both systematic reasoning processes and comprehensive medical knowledge. While recent advances in Large Language Models (LLMs) have enabled various medical educational applications, these systems often provide direct answers that could reduce students' cognitive engagement and lead to fragmented learning. Motivated by these challenges, we propose DDxTutor, a framework that follows differential diagnosis principles to decompose clinical reasoning into teachable components. It consists of a structured reasoning module that analyzes clinical clues and synthesizes diagnostic conclusions, and an interactive dialogue framework that guides students through this process. To enable such tutoring, we construct DDxReasoning, a dataset of 933 clinical cases with fine-grained diagnostic steps verified by doctors. Our experiments demonstrate that fine-tuned LLMs achieve strong performance in generating structured teaching references and conducting interactive diagnostic tutoring dialogues. Human evaluation by medical educators and students validates the framework's potential and effectiveness for clinical diagnosis education. Our project is available at https://github.com/med-air/DDxTutor .