Vermiform appendix
Revision as of 03:27, 6 February 2014 by Michael (talk | contribs) (→Neuroendocrine tumour of the appendix)
The vermiform appendix, usually just appendix, is a little thingy that is attached to the cecum. Taking it out is the bread 'n butter of general surgery.
The appendix is a vestigial structure that is thought to have arisen from a larger cecum. Larger cecae are often seen in herbivores and thought to facilitate better digestion of plant matter.[1]
Normal
Normal vermiform appendix
General
- Seen in:
- Right hemicolectomies.
- Surgeries for ovarian mucinous tumours.
Gross
- Shiny serosal surface.
- No exudate.
- Normal diameter.
- 6.6 +/- 1.5 mm -- based on CT.[2]
Microscopic
Features:
- +/-Lymphoid hyperplasia - mucosa or submucosa.
- Normal colorectal-type mucosa.
- Fatty submucosa.
- Benign smooth muscle.
- Serosa.
Negatives:
- No neutrophils in the muscularis propria.
- No lesion in appendiceal tip.
- No serosal inflammation (periappendicitis).
- No organisms in the appendiceal lumen, e.g. Enterobius vermicularis.
DDx:
- Adenovirus appendicitis.
- Cryptosporidiosis.
- Mild colitis.
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VERMIFORM APPENDIX WITHIN NORMAL LIMITS.
Negative appendectomy
General
- Common.
- Use for quality control among general surgeons.[citation needed]
Gross
See normal vermiform appendix.
Microscopic
See normal vermiform appendix.
Notes:
- Should be submitted in total.
DDx:
- Acute appendicitis.
- Adenovirus appendicitis.
- Appendiceal neuroendocrine tumour.
- Non-appendiceal pathology - see DDx of acute appendicitis.
- Isolated periappendicitis.
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VERMIFORM APPENDIX, APPENDECTOMY: - APPENDIX NEGATIVE FOR ACUTE APPENDICITIS AND NEGATIVE FOR ACUTE PERIAPPENDICITIS.
VERMIFORM APPENDIX, APPENDECTOMY: - APPENDIX WITH LYMPHOID HYPERPLASIA AND FOCAL MUCOSAL EROSIONS. - NEGATIVE FOR ACUTE APPENDICITIS. - NEGATIVE FOR ACUTE PERIAPPENDICITIS.
Micro
The sections show appendiceal wall with focal mucosa erosions and several intraluminal neutrophil clusters. Lymphoid hyperplasia is present. Fecal material is present within the lumen of the appendix.
There are no neutrophils within the muscularis propria. There is no serositis. There is no distortion of the crypt architecture. No granulomas are identified. No cryptitis is identified.
Inflammatory pathologies
Acute appendicitis
Main article: Acute appendicitis
Adenovirus appendicitis
General
- Rare type of appendicitis in children.
- Presents as run-of-the-mill acute appendicitis.
- Caused by Adenovirus.
Microscopic
Features:[3]
- Lymphoid hyperplasia - key feature.
- +/-Adenovirus inclusions; "smudge cells".
Notes:
- The classic finding of appendicitis (neutrophils infiltrating into the muscularis propria) may be absent.[3]
Image:
IHC
- Adenovirus +ve = diagnostic.
Enterobius vermicularis
Main article: Enterobius vermicularis
- AKA pinworm.
General
- May be found in the appendix.
- The incidence is higher in normal appendices than inflamed ones.[4][5]
- Clinically mimics appendicitis.[6]
Microscopic
Features:
- Usu. the appendiceal wall has no inflammation, i.e. there is no appendicitis.[4][5]
- Enterobius vermicularis organisms.
Image
Enterobius - very low mag. (WC/Nephron)
Enterobius - high mag. (WC/Nephron)
Pinworm (WC/Uthman)
.jpg)
Granulomatous appendicitis
General
Most common cause:
- Yersinia appendicitis.[7]
DDx:[8]
- Yersinia appendicitis.[7]
- Yersinia = gram negative rod (red on Gram stain).
- "Safety pin"-like appearance[9] - approximately 0.5 micrometers diameter x 2 micrometers length.
- Other micro-organism (TB, fungus).
- Crohn's disease.
- Sarcoidosis.
- Foreign body reaction.
- Interval (delayed) appendectomy.
- Approximately 60% of delayed appendectomies have granulomas.[10]
Microscopic
Features:
- Granulomas.
- +/-"Safety pin"-like organisms (Yersinia).
Image(s):
Inflammatory bowel disease
Periappendicitis
General
Definition: inflammation of tissues around the (vermiform) appendix.[11]
- May be seen in association of appendicitis or alone.
Microscopic
Features:
- Acute inflammation of the serosa.
- Neutrophils in the serosa.
DDx:
Tumours of the appendix
Adenocarcinoma
- Like colorectal adenocarcinoma - see colorectal tumours.
Mucinous tumours of the appendix
| Mucinous tumours of the appendix | |
|---|---|
| External resources | |
| EHVSC | 10183 |
- Benign appendiceal mucocele and appendiceal mucocele redirect here.
General
- There are many classifications and they are controversial.[14]
- The controversy centres on whether to call all mucinous tumours outside of the appendix adenocarcinoma - regardless of whether they have atypia & show invasion.
- Panarelli and Yantiss created a nice summary table - that compare the classifications - see: comparison of classifications (archivesofpathology.org).[14]
- In women - an ovarian primary must be excluded.
- Concurrent bilateral ovarian tumours suggests the tumour originated from the appendix and spread to the ovaries.
- Onlinepathology prefers the classification of Misdraji,[15] as it is the least complicated
Misdraji classification
- Benign - low grade mucinous tumour.
- Borderline - mucinous tumour of uncertain malignant potential or borderline mucinous tumour.
- Malignant - mucinous adenocarcinoma.
Five year survival (in a series of 107 cases) as per Misdraji classification:[15]
| Tumour | Five year survival |
|---|---|
| LAMN | 100% |
| LAMN extra-appendiceal spread | 86% |
| MACA | 44% |
- LAMN = low-grade appendiceal mucinous neoplasm.
- LAMN extra-appendiceal = low-grade appendiceal mucinous neoplasm with extra-appendiceal spread.
- MACA = mucinous adenocarcinoma of the appendix.
World Health Organization classification
WHO classification:
- Adenoma with low-grade dysplasia.
- Adenoma with high-grade dysplasia.
- Low-grade invasive mucinous adenocarcinoma
- Confined to the appendiceal wall.
- Outside of the appendix.
- High-grade invasive mucinous adenocarcinoma.
Comparison between Misdraji and WHO classification
Adapted from Panarelli and Yantiss:[14]
| Stage | Cytologic dysplasia | Misdraji | World Health Organization |
|---|---|---|---|
| Confined to the mucosa | low-grade | low-grade appendiceal mucinous neoplasm (LAMN) | mucinous adenoma, negative for high-grade dysplasia |
| Confined to the mucosa | high-grade | non-invasive mucinous cystadenocarcinoma of the appendix | mucinous adenoma with high-grade dysplasia |
| At least into the submucosa, confined to the appendix | low-grade | low-grade appendiceal mucinous neoplasm (LAMN) | invasive mucinous adenocarcinoma, low-grade |
| At least into the submucosa, confined to the appendix | high-grade | mucinous adenocarcinoma of the appendix (MACA) | invasive mucinous adenocarcinoma, high-grade |
| Extra-appendiceal spread | low-grade | low-grade appendiceal mucinous neoplasm (LAMN) | invasive mucinous adenocarcinoma, low-grade |
| Extra-appendiceal spread | high-grade | mucinous adenocarcinoma of the appendix (MACA) | invasive mucinous adenocarcinoma, high-grade |
Microscopic
Low-grade appendiceal mucinous neoplasm
- AKA benign mucinous tumour of the appendix.
Microscopic:
- Single layer of epithelium with tufts.
- Vaguely resemble serrations, i.e. the saw-tooth pattern in hyperplastic polyps of the colon.
- Mucin contained (inside appendix only).
- No marked nuclear atypia.
Note:
- May be deceptively bland appearing from a cytologic perspective.
Images:
- LAMN - low mag. (nature.com).[16]
- LAMN - high mag. (nature.com).[16]
- Appendiceal mucocele (pathlabmed.typepad.com).
Low-grade appendiceal mucinous neoplasm with extra-appendiceal spread
- AKA mucinous borderline tumour of the appendix.
Microscopic:
- Same as LAMN but mucin outside of the appendix.
- Cells in mucin, i.e. cellular mucin.
Mucinous adenocarcinoma of the appendix
- AKA malignant mucinous tumour of the appendix.
Microscopic:
- Marked nuclear pleomorphism.
- Invasion into the appendiceal wall.
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LAMN
VERMIFORM APPENDIX, APPENDECTOMY: - LOW-GRADE APPENDICEAL MUCINOUS NEOPLASM. - ACUTE APPENDICITIS. - ACUTE PERIAPPENDICITIS.
VERMIFORM APPENDIX AND CECUM, APPENDECTOMY WITH CECAL CUFF: - LOW-GRADE APPENDICEAL MUCINOUS NEOPLASM (MUCINOUS CYSTADENOMA). - MARGINS NEGATIVE FOR MUCINOUS NEOPLASM. COMMENT: No extra-appendiceal mucin is identified. There is no invasion into the appendiceal wall.
APPENDIX, APPENDECTOMY: - APPENDICEAL MUCINOUS CYSTADENOMA WITH EXTENSIVE CALCIFICATION. -- NEGATIVE FOR HIGH-GRADE DYSPLASIA. - NEGATIVE FOR MALIGNANCY.
Goblet cell carcinoid
Main article: Crypt cell carcinoma
Neuroendocrine tumour of the appendix
Main article: Neuroendocrine tumour
- Previously known as appendiceal carcinoid.
- AKA appendiceal neuroendocrine tumour, abbreviated appendiceal NET.
General
- Most common tumour of the appendix.[17]
- Not really common though - one is seen in approximately 300 appendectomies.[18]
Size matters in appendiceal NETs:[19]
- <1.0 cm - do not metastasize.
- 1.0-2.0 cm - rarely metastasize.
Gross
- Classically found in the tip of the appendix.
Image:
Appendiceal neuroendocrine tumour. (WC)
Microscopic
Features:
- Nests of cells - with fibrous stroma in between.
- May have a trabecular architecture.
- Stippled chromatin AKA salt-and-pepper chromatin, coarse chromatin.
- Classically subepithelial/mural.
DDx:
- Colorectal adenocarcinoma.
- Crypt cell carcinoma (goblet cell carcinoid).
- Metastatic adenocarcinoma.
Images=
www:
- Appendiceal carcinoid (humpath.com).
- Carcinoid of the appendix (brown.edu).
- Appendiceal carcinoid (flickr.com/Qiao).
IHC
Features:
- Chromogranin A -ve/+ve.
- Synaptophysin +ve.
See: neuroendocrine tumours.
See also
References
- ↑ Dawkins, R. (2009). The Greatest Show on Earth: The Evidence for Evolution (1st ed.). Free Press. pp. 115. ISBN 978-1416594789.
- ↑ Charoensak, A.; Pongpornsup, S.; Suthikeeree, W. (Dec 2010). "Wall thickness and outer diameter of the normal appendix in adults using 64 slices multidetector CT.". J Med Assoc Thai 93 (12): 1437-42. PMID 21344807.
- ↑ 3.0 3.1 Grynspan D, Rabah R (2008). "Adenoviral appendicitis presenting clinically as acute appendicitis". Pediatr. Dev. Pathol. 11 (2): 138–41. doi:10.2350/07-06-0299.1. PMID 17990936.
- ↑ 4.0 4.1 Wiebe, BM. (Mar 1991). "Appendicitis and Enterobius vermicularis.". Scand J Gastroenterol 26 (3): 336-8. PMID 1853157.
- ↑ 5.0 5.1 Dahlstrom, JE.; Macarthur, EB. (Oct 1994). "Enterobius vermicularis: a possible cause of symptoms resembling appendicitis.". Aust N Z J Surg 64 (10): 692-4. PMID 7945067.
- ↑ Ariyarathenam AV, Nachimuthu S, Tang TY, Courtney ED, Harris SA, Harris AM (2010). "Enterobius vermicularis infestation of the appendix and management at the time of laparoscopic appendectomy: case series and literature review". Int J Surg 8 (6): 466–9. doi:10.1016/j.ijsu.2010.06.007. PMID 20637320.
- ↑ 7.0 7.1 Lamps LW, Madhusudhan KT, Greenson JK, et al. (April 2001). "The role of Yersinia enterocolitica and Yersinia pseudotuberculosis in granulomatous appendicitis: a histologic and molecular study". Am. J. Surg. Pathol. 25 (4): 508–15. PMID 11257626.
- ↑ http://granuloma.homestead.com/appendicitis.html
- ↑ URL: http://www.cdc.gov/ncidod/dvbid/plague/p1.htm. Accessed on: 30 June 2011.
- ↑ Guo, G.; Greenson, JK. (Aug 2003). "Histopathology of interval (delayed) appendectomy specimens: strong association with granulomatous and xanthogranulomatous appendicitis.". Am J Surg Pathol 27 (8): 1147-51. PMID 12883248.
- ↑ URL: http://www.medilexicon.com/medicaldictionary.php?t=66889. Accessed on: 1 June 2011.
- ↑ Fink, AS.; Kosakowski, CA.; Hiatt, JR.; Cochran, AJ. (Jun 1990). "Periappendicitis is a significant clinical finding.". Am J Surg 159 (6): 564-8. PMID 2349982.
- ↑ O'Neil, MB.; Moore, DB. (Sep 1977). "Periappendicitis: Clinical reality or pathologic curiosity?". Am J Surg 134 (3): 356-7. PMID 900337.
- ↑ 14.0 14.1 14.2 Panarelli, NC.; Yantiss, RK. (Oct 2011). "Mucinous neoplasms of the appendix and peritoneum.". Arch Pathol Lab Med 135 (10): 1261-8. doi:10.5858/arpa.2011-0034-RA. PMID 21970481.
- ↑ 15.0 15.1 Misdraji J, Yantiss RK, Graeme-Cook FM, Balis UJ, Young RH (August 2003). "Appendiceal mucinous neoplasms: a clinicopathologic analysis of 107 cases". Am. J. Surg. Pathol. 27 (8): 1089–103. PMID 12883241. http://meta.wkhealth.com/pt/pt-core/template-journal/lwwgateway/media/landingpage.htm?issn=0147-5185&volume=27&issue=8&spage=1089.
- ↑ 16.0 16.1 Misdraji, J.; Burgart, LJ.; Lauwers, GY. (Dec 2004). "Defective mismatch repair in the pathogenesis of low-grade appendiceal mucinous neoplasms and adenocarcinomas.". Mod Pathol 17 (12): 1447-54. doi:10.1038/modpathol.3800212. PMID 15354187.
- ↑ Mitchell, Richard; Kumar, Vinay; Fausto, Nelson; Abbas, Abul K.; Aster, Jon (2011). Pocket Companion to Robbins & Cotran Pathologic Basis of Disease (8th ed.). Elsevier Saunders. pp. 435. ISBN 978-1416054542.
- ↑ Mitra, B.; Pal, M.; Paul, B.; Saha, TN.; Maiti, A. (2013). "Goblet cell carcinoid of appendix: A rare case with literature review.". Int J Surg Case Rep 4 (3): 334-7. doi:10.1016/j.ijscr.2013.01.007. PMID 23416502.
- ↑ Modlin, IM.; Lye, KD.; Kidd, M. (Feb 2003). "A 5-decade analysis of 13,715 carcinoid tumors.". Cancer 97 (4): 934-59. doi:10.1002/cncr.11105. PMID 12569593.