Pathognomonic

{{Short description|Medical term meaning "characteristic for a particular disease"}} '''Pathognomonic''' (synonym ''pathognomic''<ref>{{cite web|url=https://en.oxforddictionaries.com/definition/pathognomic |archive-url=https://web.archive.org/web/20180527120714/https://en.oxforddictionaries.com/definition/pathognomic |url-status=dead |archive-date=May 27, 2018 |publisher=Oxford Dictionaries |title=Pathognomic}}</ref>) 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. The absence of a pathognomonic sign does not rule out the disease. Labelling a sign or symptom "pathognomonic" represents a marked intensification of a "diagnostic" sign or symptom.

The word is an adjective of Greek origin derived from πάθος ''pathos'' 'disease' and γνώμων ''gnomon'' 'indicator' (from γιγνώσκω ''gignosko'' 'I know, I recognize').

== 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 has very high positive predictive value and high specificity but does not need to have high sensitivity: 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 allows immediate diagnosis, since there are no other conditions in the differential diagnosis.{{citation needed|date=December 2021}}

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, Negri bodies within brain tissue infected with rabies, or a tetrad of rash, arthralgia, abdominal pain and kidney disease in a child with Henoch–Schönlein purpura, or succinylacetone for Tyrosinemia Type I.{{citation needed|date=December 2021}}

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. An 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).{{citation needed|date=December 2021}}

In contrast, a test with very high sensitivity rarely misses a condition, so a negative result should be reassuring (the disease tested for is absent). A sign or symptom with very high sensitivity is often termed ''sine qua non''. An example of such test is a genetic test to find an underlying mutation in certain types of hereditary colon cancer.<ref>{{cite journal | vauthors = Lynch HT, Lynch JF, Lynch PM, Attard T | title = Hereditary colorectal cancer syndromes: molecular genetics, genetic counseling, diagnosis and management | journal = Familial Cancer | volume = 7 | issue = 1 | pages = 27–39 | year = 2007 | pmid = 17999161 | doi = 10.1007/s10689-007-9165-5 | s2cid = 20103607 }}</ref><ref>{{cite journal | vauthors = Lynch HT, Lanspa SJ | title = Colorectal cancer survival advantage in MUTYH-associated polyposis and Lynch syndrome families | journal = Journal of the National Cancer Institute | volume = 102 | issue = 22 | pages = 1687–9 | date = November 2010 | pmid = 21044965| doi = 10.1093/jnci/djq439 }}</ref>

==Examples== {| class="sortable wikitable" ! Disease || Sign |- | Cytomegalovirus infection || Owl's eye appearance of inclusion bodies<ref>Page 268 in: {{cite book | last1 = Gibbs | first1 = Ronald Darnley | last2 = Sweet | first2 = Richard L. | name-list-style = vanc |title=Infectious Diseases of the Female Genital Tract |publisher=Lippincott Williams & Wilkins |location=Hagerstwon, MD |year=2009 |isbn=978-0-7817-7815-2 }}</ref><ref>{{cite journal | vauthors = Mattes FM, McLaughlin JE, Emery VC, Clark DA, Griffiths PD | title = Histopathological detection of owl's eye inclusions is still specific for cytomegalovirus in the era of human herpesviruses 6 and 7 | journal = Journal of Clinical Pathology | volume = 53 | issue = 8 | pages = 612–4 | date = August 2000 | pmid = 11002765 | pmc = 1762915 | doi = 10.1136/jcp.53.8.612 }}</ref> |- | Lyme disease || Erythema chronicum migrans<ref>{{cite journal | vauthors = Ogden NH, Lindsay LR, Morshed M, Sockett PN, Artsob H | title = The rising challenge of Lyme borreliosis in Canada | journal = Canada Communicable Disease Report | volume = 34 | issue = 1 | pages = 1–19 | date = January 2008 | pmid = 18290267 | url = http://www.phac-aspc.gc.ca/publicat/ccdr-rmtc/08vol34/dr-rm3401a-eng.php }}</ref> |- | Inclusion body myositis || Filamentous material seen in inclusion bodies under electron microscopy |- | Hypocalcemia || Trousseau sign and Chvostek sign |- | Tetanus or strychnine poisoning || Risus sardonicus |- | Measles || Koplik's spots |- | Wilson's disease || Kayser–Fleischer ring |- | Diphtheria || Pseudomembrane on tonsils, pharynx and nasal cavity |- | Chronic hemorrhagic pancreatitis || Grey-Turner's sign (ecchymosis in flank area) |- | Cholera || Rice-watery stool |- | Enteric fever || Rose spots in abdomen |- | Meningitis || Kernig's sign and Brudzinski's sign |- | Angina pectoris || Levine's sign (hand clutching of chest)<ref>{{cite book | url=https://books.google.com/books?id=Kse7AgAAQBAJ&q=%22Levine%27s+sign%22+pathognomonic&pg=PA355 | title=Textbook of Physical Diagnosis: History and Examination | publisher=Elsevier | first = Mark H. | last = Swartz | name-list-style = vanc | year=2014 | pages=354 | isbn=9780323225076}}</ref> |- | Patent ductus arteriosus || Machine-like murmur |- | Parkinson's disease{{citation needed|date=April 2014}} || Pill-rolling tremors{{citation needed|date=April 2014}} |- | Whipple's disease || Oculo-masticatory myorhythmia |- | Acute myeloid leukemia || Auer rod |- | Multiple sclerosis || Bilateral internuclear ophthalmoplegia |- | Pericarditis || Pericardial friction rub |- | Rheumatic fever || Aschoff bodies |- | Rabies || Hydrophobia and Negri bodies |- | Gout || Tophi |- | Acute tubular necrosis || Muddy brown casts |- |Granulosa cell tumour |Call-Exner bodies |- |Malakoplakia |Michaelis–Gutmann bodies |- |Narcolepsy (with cataplexy) |Cataplexy |- |Endodermal sinus tumor |Schiller–Duval body |- |Parkinson's disease |Rigidity with tremor<ref>{{Cite book |last=Arslan |first=Orhan E. |title=Neuroanatomical Basis of Clinical Neurology, Second Edition |date=2015 |publisher=CRC Press |isbn=978-1-4398-4834-0 |edition=2nd |location=Hoboken |page=473}}</ref> |- |Atrial flutter |Flutter waves<ref>{{cite journal |last1=Bernstein |first1=Neil E. |last2=Sandler |first2=David A. |last3=Goh |first3=Mark |last4=Feigenblum |first4=David Y. |last5=Holmes |first5=Douglas S. |last6=Chinitz |first6=Larry A. |title=Why a Sawtooth? Inferences on the Generation of the Flutter Wave during Typical Atrial Flutter Drawn from Radiofrequency Ablation |journal=Annals of Noninvasive Electrocardiology |date=15 October 2004 |volume=9 |issue=4 |pages=358–361 |doi=10.1111/j.1542-474X.2004.94576.x |pmid=15485514 |pmc=6932011 }}</ref> |- |Sickle cell disease |Vaso-occlusive crises<ref>{{cite journal | vauthors = Rami Helvaci M, Ayyildiz O, Gundogdu M | title = Gender differences in severity of sickle cell diseases in non-smokers | journal = Pakistan Journal of Medical Sciences | volume = 29 | issue = 4 | pages = 1050–4 | date = July 2013 | pmid = 24353686 | pmc = 3817781 }}</ref> |- |Lightning injury |Lichtenberg figure on skin<ref>{{cite journal | pmc=8226253 | date=2021 | last1=Lindford | first1=A. | last2=Juteau | first2=S. | last3=Jaks | first3=V. | last4=Klaas | first4=M. | last5=Lagus | first5=H. | last6=Vuola | first6=J. | last7=Kankuri | first7=E. | title=Case Report: Unravelling the Mysterious Lichtenberg Figure Skin Response in a Patient with a High-Voltage Electrical Injury | journal=Frontiers in Medicine | volume=8 | doi=10.3389/fmed.2021.663807 | doi-access=free | pmid=34179045 }}</ref><ref>{{cite journal | url=https://ui.adsabs.harvard.edu/abs/2015JASTP.136..119C/abstract | bibcode=2015JASTP.136..119C | title=On the possible mechanism of keraunographic markings on lightning victims | last1=Cooray | first1=Vernon | last2=Cooray | first2=Gerald K. | last3=Cooray | first3=Charith | journal=Journal of Atmospheric and Solar-Terrestrial Physics | date=2015 | volume=136 | page=119-123 | doi=10.1016/j.jastp.2015.06.006 }}</ref> |}

== References == {{reflist}}

== External links == {{Wiktionary}} * [https://www.youtube.com/watch?v=2DqSvQEAp6U Slide show with audio summary of 122 pathognomonic signs]

Category:Medical terminology Category:Medical signs Category:Symptoms