BackgroundContrastive learning is known to be effective in teaching medical students how to generate diagnostic hypotheses in clinical reasoning. However, there is no international consensus on lists of diagnostic considerations across different medical disciplines regarding the common signs and symptoms that should be learned as part of the undergraduate medical curriculum. In Japan, the national model core curriculum for undergraduate medical education was revised in 2016, and lists of potential diagnoses for 37 common signs, symptoms, and pathophysiology were introduced into the curriculum. This study aimed to validate the list of items based on expert consensus.MethodsThe authors used a modified Delphi method to develop consensus among a panel of 23 expert physician-teachers in clinical reasoning from across Japan. The panel evaluated the items on a 5-point Likert scale, based on whether a disease should be hypothesized by final-year medical students considering given signs, symptoms, or pathophysiology. They also added other diseases that should be hypothesized. A positive consensus was defined as both a 75% rate of panel agreement and a mean of 4 or higher with a standard deviation of less than 1 on the 5-point scale. The study was conducted between September 2017 and March 2018.ResultsThis modified Delphi study identified 275 basic and 67 essential other than basic items corresponding to the potential diagnoses for 37 common signs, symptoms, and pathophysiology that Japanese medical students should master before graduation.ConclusionsThe lists developed in the study can be useful for teaching and learning how to generate initial hypotheses by encouraging students’ contrastive learning. Although they were focused on the Japanese educational context, the lists and process of validation are generalizable to other countries for building national consensus on the content of medical education curricula.