ABNORMAL EMOTIONAL EXPERIENCE IN SCHIZOPHRENIA
there are no symptoms of schizophrenia that hold across all cases of the
disorder (Cohen & Docherty, 2005); nor are there any endogenous signatures (e.g.,
neuroanatomical deformity, pathophysiological process) that may serve as pathognomonic
indicators of the disease (Keshavan, Tandon, Boutros, & Nasrallah, 2008).
http://etd.lsu.edu/docs/available/etd-12112012-171800/unrest...

Toward Validation of the Diagnosis of Posttraumatic Stress Disorder
Carol S. North, M.D., M.P.E.; Alina M. Suris, Ph.D.; Miriam Davis, Ph.D.; Rebecca P. Smith, M.D.
Traditional tests of the validity of these criteria entail demonstration of etiology, pathogenesis, illness course, including response to treatment, and familial patterns. Few diseases have one necessary and sufficient cause orpathognomonic indicators
http://ajp.psychiatryonline.org/article.aspx?articleID=10045...

Pathognomonic (often misspelled as pathognomic and sometimes as pathomnemonic) is a term, often used in medicine, that means characteristic for a particular disease. A pathognomonic sign is a particular sign whose presence means that a particular disease is present beyond any doubt. Labelling a sign or symptom "pathognomonic" represents a marked intensification of a "diagnostic" sign or symptom.
http://en.wikipedia.org/wiki/Pathognomonic