The presentation of interesting cases has a long tradition as an educational tool and contributes tolifelong learning. Discussing the clinical course and management of individual patients enhances ourunderstanding of disease and provides a framework for learning about medical advances.The New England Journal of Medicine publishes several case-based series including Case Recordsof the Massachusetts General Hospital, Clinical Problem-Solving, and Clinical Practice, plusour online Interactive Medical Cases. We have chosen the cases in this collection based on their clinicalrelevance to primary care. We hope you find this collection engaging and instructive.Edward W. Campion, MDExecutive Editor and Online EditorThe New England Journal of Medicine