"The basic definition of a case report is the detailed report of an individual including aspects like exposure, symptoms, signs, intervention, and outcome. . . . A case report may describe an unusual etiology, an unusual or unknown disorder, a challenging differential diagnosis, an unusual setting for care, information that can not be reproduced due to ethical reasons, unusual or puzzling clinical features, improved or unique technical procedures, unusual interactions, rare or novel adverse reactions to care, or new insight into the pathogenesis of disease."
Source: Garg R, Lakhan SE, Dhanasekaran AK. How to review a case report. J Med Case Rep. 2016 Apr 6;10:88. doi: 10.1186/s13256-016-0853-3