Abstract: A knowledge base having particular utility as a medical/pathology knowledge base contains textual and pictorial information on various diseases. The knowledge base includes user-selectable designations of diagnostic features which are characteristic of respective conditions to be diagnosed. These features comprise a case record and several case records are stored and retrieved for subsequent display of the features therein and of one or more pictorial images of those features. The pictorial images preferably are stored on a device such as an optical disk; and these pictorial images are linked to case records which may be stored in other storage devices, such as magnetic disk, whereby the retrieval of a case record accesses the linked pictorial images, whereby those pictorial images and features of the case record are displayed.