Case reports and case series in epidemiology and medicine are a type of descriptive study based on singular or grouped uncontrolled observations of patients. Case reports are defined here as singular reports on one individual patient, while case series are collections of information on more than one patient. The subjects in a series usually share one or more common characteristics, such as disease, treatment, or side effect. Usually subjects are followed for a period of time to observe a particular outcome; however, for reasons often to do with convenience or practicability, series may be retrospective collections of patient histories. A series may also be purely descriptive of a point in time—for example, describing variations of clinical presentations. While some series are purely observational, case series ...