Pathognomonic

Pathognomonic (rare synonym pathognomic[1]) 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 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 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.

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.

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).

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.[2][3]

Examples

Disease	Sign
Cytomegalovirus infection	Owl's eye appearance of inclusion bodies[4][5]
Hodgkin's lymphoma	Reed-Sternberg cells (giant mono- and multinucleated cells) upon microscopy
Lyme disease	Erythema chronicum migrans[6]
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)[7]
Patent ductus arteriosus	Machine-like murmur
Parkinson's disease	Pill-rolling tremors
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
MASC	ETV6-NTRK3
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
Sickle cell disease	Vaso-occlusive crises[8]

See also

• AIDS defining clinical condition
• List of eponymous medical signs
• Medical sign
• Sine qua non

References

1. "Pathognomic". Oxford Dictionaries.
2. Lynch HT, Lynch JF, Lynch PM, Attard T (2007). "Hereditary colorectal cancer syndromes: molecular genetics, genetic counseling, diagnosis and management". Familial Cancer. 7 (1): 27–39. doi:10.1007/s10689-007-9165-5. PMID 17999161.
3. Lynch HT, Lanspa SJ (November 2010). "Colorectal cancer survival advantage in MUTYH-associated polyposis and Lynch syndrome families". Journal of the National Cancer Institute. 102 (22): 1687–9. doi:10.1093/jnci/djq439.
4. Page 268 in: Gibbs RD, Sweet RL (2009). Infectious Diseases of the Female Genital Tract. Hagerstwon, MD: Lippincott Williams & Wilkins. ISBN 0-7817-7815-8.
5. Mattes FM, McLaughlin JE, Emery VC, Clark DA, Griffiths PD (August 2000). "Histopathological detection of owl's eye inclusions is still specific for cytomegalovirus in the era of human herpesviruses 6 and 7". Journal of Clinical Pathology. 53 (8): 612–4. doi:10.1136/jcp.53.8.612. PMC 1762915. PMID 11002765.
6. Ogden NH, Lindsay LR, Morshed M, Sockett PN, Artsob H (January 2008). "The rising challenge of Lyme borreliosis in Canada". Canada Communicable Disease Report. 34 (1): 1–19. PMID 18290267.
7. Swartz MH (2014). Textbook of Physical Diagnosis: History and Examination. Elsevier. p. 354. ISBN 9780323225076.
8. Rami Helvaci M, Ayyildiz O, Gundogdu M (July 2013). "Gender differences in severity of sickle cell diseases in non-smokers". Pakistan Journal of Medical Sciences. 29 (4): 1050–4. PMC 3817781. PMID 24353686.

External links

• Slide show with audio summary of 122 pathognomonic signs