Psychsomatic disorders are symptoms of illness and disease processes that look and feel real, especially to the patient, but appear to lack any visible known pathology to support a physiological diagnosis. The victim of these types of disorders are generally believed to show excessive concern for the disease process.
For instance, a young mother might develop frequent, severe, headaches and deduce that she must have a brain tumor. However, following a doctor's exam the headaches are diagnosed as being stress-related.
However, it must be noted that as medical knowledge has grown it is being learned that diseases that were previously believed to have been purely stress-related are being found to have physiological components also.