Pathognomonic

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.

The word is an adjective of Greek origin (παθογνωμονικό [σύμπτωμα]), derived from páthos ("πάθος" meaning "disease") and gnōmon ("γνώμον" meaning "judge").

Practical use

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 sign or symptom is specific but need not be sensitive: for example it 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. The presence of a pathognomonic finding, on the other hand, allows immediate diagnosis, since there are no other conditions in the differential diagnosis.

Singular pathognomonic signs are relatively uncommon. Examples of pathognomonic findings include Koplik's spots inside the mouth in measles, the palmar xanthomata seen on the hands of people suffering from hyperlipoproteinemia, or a tetrad of rash, arthralgia, abdominal pain and kidney disease in a child with Henoch-Schönlein purpura.

As opposed to symptoms (reported subjectively by the patient and not measured) and signs (observed by the physician at the bedside on physical exam, without need for a report) a larger number of medical test results are pathognomonic. A example is the hypersegmented neutrophil, which is seen only in megaloblastic anemias (not a single disease, but a set of closely related disease states). More often a test result is "pathognomonic" only because there has been a consensus to define the disease state in terms of the test result (such as diabetes mellitus being defined in terms of chronic fasting blood glucose levels).

Examples

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.

Disease	Sign
Cytomegalovirus infection	Owl's eye appearance of inclusion bodies
Inclusion body myositis	Filamentous material seen in inclusion bodies under electron microscopy
Hypocalcemia	Trousseau sign and Chvostek sign
Tetanus	Risus sardonicus
Bulimia Nervosa	Chipmunk facies (parotid gland swelling) (Chipmunk facies also seen in marrow expansion secondary to Beta Thalassemia Major)
Leprosy	Leonine facies (thickened lion-like facial skin)
Measles	Koplik's spots
Diphtheria	Pseudomembrane on tonsils, pharynx and nasal cavity
Pancreatitis	Cullen's sign (bluish discoloration of umbilicus)
Chronic hemorrhagic pancreatitis	Grey-Turner's sign (ecchymosis in flank area)
Cholera	Rice-watery stool
Typhoid fever	Rose spots in abdomen
Meningitis	Kernig's sign and Brudzinski's sign
Cholecystitis	Murphy's sign (pain on deep inspiration when inflamed gallbladder is palpated)
Angina pectoris	Levine's sign (hand clutching of chest)
Patent ductus arteriosus	Machine-like murmur
Pleural Effusion	Stony-dull percussion
Parkinson's disease	Pill-rolling tremors
Whipple's disease	Oculo-Masticatory Myorhythmia
Acute Myeloid Leukemia	Auer rod
Multiple Sclerosis	Bilateral internuclear ophthalmoplegia
Congestive heart failure	Third heart sound
Pericarditis	Pericardial friction rub
Neurofibromatosis I	Plexiform neurofibroma
Hodgkin's lymphoma	Hodgkin and Reed-Sternberg cells (giant mono- and multinucleated cells)
Pyelonephritis	White blood cell casts
Rheumatic fever	Aschoff nodules

See also

• Medical sign
• List of eponymous medical signs
• Sine qua non

External links

de:Pathognomonisch sv:Patognomon