The Cleveland Clinic describes a person with the somatoform disorder, hypochondriasis: … [They] are very worried about getting a disease or are certain they have a disease, even after medical tests show they do not. Further, these people often misinterpret minor health problems or normal body functions as symptoms of a serious disease. An example is a person who is sure that his or her headaches are caused by a brain tumor. The symptoms associated with hypochondriasis are not under the person’s voluntary control, and can cause great distress and/or can interfere with a person’s normal functioning.
Dr. French Fry describes a hypochondriac: a medical student, who, after reading a new chapter in his/her pathology textbook, is quite certain the clinical manifestations of no less than three diseases match his/her vague symptoms. An example, a medical student reads the chapter on the gastrointestinal tract and is sure that his/her abdominal pain is not due to the large meal he/she ate an hour before, but due to 1) a blind pouch communicating with the lumen of his/her gut; 2) a transmural infarction caused by occlusion of a major mesenteric artery; or 3) a bowel obstruction cause by a intraluminal mass (a tumor).