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==Pathophysiology==
==Pathophysiology==
Pseudomyxoma peritonei refers to intraperitoneal accumulation of a gelatinous ascites secondary to rupture of a mucinous tumor. The most common cause is a ruptured mucinous tumor of the appendix / appendiceal mucocoele.
The pathological process starts with neoplastic transformation of the appendiceal goblet cells and subsequent formation of a primary mucinous tumor. While proliferating, tumor cells maintain their constitutive level of mucin expression. As a result, the overall secretion of mucin dramatically rises[8]. This is followed by intraluminal accumulation of mucin and eventual development of an appendiceal mucocele. A small perforation or rupture of the mucocele is the key event towards the development of PMP through which tumor cells gain access into the peritoneal cavity. Lacking cell surface adhesion molecules, the exfoliated tumor cells passively circulate with the peritoneal fluid and redistribute throughout the peritoneal cavity. As a result, tumor implants and mucin collections form at the peritoneal fluid reabsorption sites as well as within the dependent portions of the peritoneal cavity to create PMP’s characteristic pattern of the peritoneal dissemination (Figure 1)[11]. Accumulating mucin increases intraabdominal pressure and compresses visceral organs. Furthermore, extensive involvement of the peritoneal surface promotes variable inflammatory and fibrotic responses in the peritoneal environment and hence the development of bowel obstruction as a fatal complication of the disease.<ref name="AminiMasoumi-Moghaddam2014">{{cite journal|last1=Amini|first1=Afshin|last2=Masoumi-Moghaddam|first2=Samar|last3=Ehteda|first3=Anahid|last4=Morris|first4=David|title=Secreted mucins in pseudomyxoma peritonei: pathophysiological significance and potential therapeutic prospects|journal=Orphanet Journal of Rare Diseases|volume=9|issue=1|year=2014|pages=71|issn=1750-1172|doi=10.1186/1750-1172-9-71}}</ref>


Pseudomyxoma peritonei is commonly discovered during surgery for other conditions, i.e., hernia repair, following which an experienced pathologist can confirm the diagnosis. Due to the rarity of this disease, it is important to obtain an accurate diagnosis so that appropriate treatment may be obtained.
==Pathology==
==Pathology==



Revision as of 18:35, 19 November 2015

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Parminder Dhingra, M.D. [2]

Overview

Pathophysiology

The pathological process starts with neoplastic transformation of the appendiceal goblet cells and subsequent formation of a primary mucinous tumor. While proliferating, tumor cells maintain their constitutive level of mucin expression. As a result, the overall secretion of mucin dramatically rises[8]. This is followed by intraluminal accumulation of mucin and eventual development of an appendiceal mucocele. A small perforation or rupture of the mucocele is the key event towards the development of PMP through which tumor cells gain access into the peritoneal cavity. Lacking cell surface adhesion molecules, the exfoliated tumor cells passively circulate with the peritoneal fluid and redistribute throughout the peritoneal cavity. As a result, tumor implants and mucin collections form at the peritoneal fluid reabsorption sites as well as within the dependent portions of the peritoneal cavity to create PMP’s characteristic pattern of the peritoneal dissemination (Figure 1)[11]. Accumulating mucin increases intraabdominal pressure and compresses visceral organs. Furthermore, extensive involvement of the peritoneal surface promotes variable inflammatory and fibrotic responses in the peritoneal environment and hence the development of bowel obstruction as a fatal complication of the disease.[1]

Pathology

The remarkable feature of pseudomyxoma peritonei is that this neoplastic, progressive process often arises from a seemingly benign or well differentiated primary tumor.

Pseudomyxoma peritonei may be divided into two pathological subtypes which have aetiological and prognostic significance:

Peritoneal adenomucinosis

A peritoneal neoplasm composed largely of mucin associated with fibrosis with minimal cytologic atypia and mitoses The primary tumor is generally an adenoma

Peritoneal mucinous carcinoma

A peritoneal neoplasm characterised by proliferative epithelium, glands, nests, or individual cells with marked cytologic atypia The primary tumor is a mucinous adenocarcinoma

Not all cases fit neatly into these categories, and many patients have intermediate or discordant features.

References

  1. Amini, Afshin; Masoumi-Moghaddam, Samar; Ehteda, Anahid; Morris, David (2014). "Secreted mucins in pseudomyxoma peritonei: pathophysiological significance and potential therapeutic prospects". Orphanet Journal of Rare Diseases. 9 (1): 71. doi:10.1186/1750-1172-9-71. ISSN 1750-1172.


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