Editing Appendicitis (section)

===Pathology===
Even for clinically certain appendicitis, routine [[histopathology]] examination of appendectomy specimens is of value for identifying unsuspected pathologies requiring further postoperative management.<ref name="Abd Al-Fatah2017">{{cite journal|last1=Abd Al-Fatah|first1=Mohamed|title=Importance of histopathological evaluation of appendectomy specimens|journal=Al-Azhar Assiut Medical Journal|volume=15|issue=2|year=2017|pages=97|issn=1687-1693|doi=10.4103/AZMJ.AZMJ_19_17|s2cid=202550141|doi-access=free}}</ref> No sign of appendicitis in specimens, negative appendectomy, varies but has been estimated to occur in 13% of specimens.<ref>{{Cite journal |last1=Henriksen |first1=Siri R. |last2=Christophersen |first2=Camilla |last3=Rosenberg |first3=Jacob |last4=Fonnes |first4=Siv |date=2023-05-23 |title=Varying negative appendectomy rates after laparoscopic appendectomy: a systematic review and meta-analysis |url=https://link.springer.com/10.1007/s00423-023-02935-z |journal=Langenbeck's Archives of Surgery |language=en |volume=408 |issue=1 |page=205 |doi=10.1007/s00423-023-02935-z |pmid=37219616 |issn=1435-2451}}</ref> Notably, [[appendix cancer]] is found incidentally in about 1% of appendectomy specimens.<ref name="LeeChoi2011">{{cite journal|last1=Lee|first1=Won-Suk|last2=Choi|first2=Sang Tae|last3=Lee|first3=Jung Nam|last4=Kim|first4=Keon Kug|last5=Park|first5=Yeon Ho|last6=Baek|first6=Jeong Heum|title=A retrospective clinicopathological analysis of appendiceal tumors from 3,744 appendectomies: a single-institution study|journal=International Journal of Colorectal Disease|volume=26|issue=5|year=2011|pages=617–621|issn=0179-1958|doi=10.1007/s00384-010-1124-1|pmid=21234578|s2cid=12566272}}</ref><ref>{{Cite journal |last1=Henriksen |first1=Siri Rønholdt |last2=Rosenberg |first2=Jacob |last3=Fonnes |first3=Siv |date=2023 |title=Other Pathologies Were Rarely Reported after Laparoscopic Surgery for Suspected Appendicitis: A Systematic Review and Meta-Analysis |url=https://karger.com/DSU/article/doi/10.1159/000531283 |journal=Digestive Surgery |language=en |volume=40 |issue=3–4 |pages=91–99 |doi=10.1159/000531283 |pmid=37463567 |issn=0253-4886}}</ref>

Pathology diagnosis of appendicitis can be made by detecting a [[neutrophil]]ic infiltrate of the [[muscularis propria]].

Periappendicitis (inflammation of tissues around the appendix) is often found in conjunction with other abdominal pathology.<ref name=pmid2349982>{{cite journal | vauthors = Fink AS, Kosakowski CA, Hiatt JR, Cochran AJ | title = Periappendicitis is a significant clinical finding | journal = American Journal of Surgery | volume = 159 | issue = 6 | pages = 564–568 | date = June 1990 | pmid = 2349982 | doi = 10.1016/S0002-9610(06)80067-X }}</ref>

<gallery>
File:Appendicitis - low mag.jpg|[[Micrograph]] of appendicitis and periappendicitis. [[H&E stain]]
File:Acute appendicitis High Power.jpg|Micrograph of appendicitis showing neutrophils in the muscularis propria. H&E stain
File:Acute suppurative appendicitis with perforation.jpg|Acute suppurative appendicitis with perforation (at right). H&E stain
</gallery>

{|class=wikitable
|+ Classification of acute appendicitis based on [[gross pathology]] and [[light microscopy]] characteristics<ref name="Carr2000">{{cite journal|last1=Carr|first1=Norman J.|title=The pathology of acute appendicitis|journal=Annals of Diagnostic Pathology|volume=4|issue=1|year=2000|pages=46–58|issn=1092-9134|doi=10.1016/S1092-9134(00)90011-X|pmid=10684382}}</ref>
|-
! Pattern !! Gross pathology !! Light microscopy !! Image !! Clinical significance
|-
! Acute intraluminal inflammation
| None visible ||
* Only neutrophils in the lumen
* No ulceration or transmural inflammation
| [[File:Histopathology of acute intraluminal inflammation of the appendix.jpg|190px]]
| Probably none
|-
! Acuta mucosal inflammation
| None visible ||
* Neutrophils within the mucosa, and possibly in the submucosa
* Mucosal ulceration
|
| May be secondary to [[enteritis]].
|-
! Suppurative acute appendicitis
| May be inapparent.
* Dull mucosa
* Congested surface vessels
* Fibropurulent serosal exudate in late cases
* Dilated appendix
|
* Neutrophils in the mucosa, submucosa, and muscularis propria, potentially transmural.
* Extensive inflammation
* Commonly intramural abscesses
* Possibly vascular thrombosis
| [[File:Acute suppurative appendicitis with perforation.jpg|190px]]
| Can be presumed to be the primary cause of symptoms
|-
! Gangrenous/necrotizing appendicitis
|
* Friable wall
* Purple, green, or black color
|
* Transmural inflammation, obliterating normal histological structures
* Necrotic areas
* Extensive mucosal ulceration
| [[File:Histopathology of necrotizing appendicitis, high magnification.jpg|190px]]
| Will perforate if untreated
|-
! Periappendicitis
| May be inapparent.
* Serosa may be congested, dull, and exudative
|
* Serosal and subserosal inflammation, no further than outer muscularis propria to be called isolated
| [[File:Histopathology of periappendicitis.jpg|190px]]
| If isolated, probably secondary to other disease
|-
! Eosinophilic appendicitis
| None visible
|
* >10 eosinophils/mm<sup>2</sup> in muscularis propria.
* No changes conforming to other types of appendicitis
|
| Possibly parasitic, or eosinophilic enteritis.
|}