Pathognomonic (often misspelled as "pathognomic" and sometimes as "pathomnemonic") is an adjective of Greek origin (παθογνωμονικό [σύμπτωμα] ), often used in
medicine, which means "diagnostic for a particular disease". A pathognomonic sign is a particular sign whose presence means, beyond any doubt, that a particular disease is present. It is derived from the Greek "páthos" (πάθος, disease) and gnōmon (γνώμον, "judge"). Labelling a sign or symptom"pathognomonic" represents a marked intensification of a "diagnostic" sign or symptom.
While some findings may be classic, typical or highly suggestive in a certain condition, they may not occur uniquely in this condition and therefore may not directly imply a specific diagnosis. A pathognomonic finding on the other hand allows immediate diagnosing, since there are no other conditions in the
differential diagnosis. A pathognomonic sign or symptom can sometimes be absent in a certain disease, since the term only implies that when it is present, the doctor instantly knows the patient's illness.
Singular pathognomonic signs are relatively uncommon. Examples of pathognomonic findings include
Koplik's spotsinside the mouthin measles, the palmar xanthomata seen on the hands of people suffering from hyperlipoproteinemia, or a tetrad of rash, arthralgia, abdominal painand kidneydisease in a child with Henoch-Schönlein purpura.
None or very few of the examples here are pathognomonic in the true sense of the word. For example, Parkinsonism is not only seen in Parkinson's disease.
List of eponymous medical signs
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