Mucocele of the appendix is a term used to describe a dilated, mucin-filled appendix. It is most commonly the result of epithelial proliferation, but can be caused. Appendiceal mucoceles occur when there is an abnormal accumulation of mucin causing abnormal distention of the vermiform appendix due to various. Appendiceal Mucocele: A Diagnostic Dilemma in Differentiating Malignant From Benign Lesions With CT. Hao Wang1, Yong-Qi Chen2, Ran Wei1, Qing-Bing.
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Mucocele of the appendix: Mucocele of the appendix is a rare disease. It can be triggered by benign or malignant diseases, which cause the obstruction of the appendix and the consequent accumulation of mucus secretion. The preoperative diagnosis is difficult due muckcele non-specific clinical manifestations of the disease. Imaging tests can suggest the diagnosis. The treatment is always surgical and depends on the integrity and size of the appendix base and on the histological type of the original lesion.
Appendiceal Mucocele: Benign or Malignant?
The prognosis is good in cases of integrity of the appendix. The perforation of the appendix and subsequent extravasation of its contents into the abdominal cavity may lead to pseudomyxoma peritonei, which mucoceele very poor prognosis if not treated properly. The mucocele of the appendix was first described in by Rokitansky 1. This disease is considered as a rare lesion of the appendix, which is found in 0.
It is characterized by the dilation of the organ lumen with mucus accumulation, being more frequent among mcocele aged 50 years or more 3,4. Gender prevalence is controversial. Appendix mucocele may come as a consequence of obstructive or inflammatory processes, cystadenomas or cystadenocarcinomas 7.
Besides these causes, other tumor lesions in the appendix or cecum may present as mucocele 8.
Its main complication is pseudomyxoma peritonei. Treatment is always surgery and determined by the organ’s integrity, the dimensions of the base and histological type of the lesion. Revista Brasileira de Coloproctologia has recently published two articles about this disease. The first one defends the right colectomy as a treatment 9and the second one recommends only appendectomy Despite the different adopted conducts, in both reported cases a cystadenoma was diagnosed in the appendix; the choice was for elective surgery.
The objective of this review is to analyze literature as to mucocele, especially regarding diagnosis and treatment, besides discussing follow-up and prognosis of the individuals who have this disease. The mucocele of the appendix is a descriptive and unspecific term to define the cystic dilation of the appendix caused by the accumulation of mucus secretion. This process is slow and gradual, with no signs of infection inside the organ. It results from the lumen obstruction in the appendix, which is secondary to the inflammatory or neoplastic proliferation of the appendix mucosa, or of lesions in the cecum, adjacent to the appendiceal ostium.
While some articles confirm its prevalence among women 3,4others demonstrate a higher incidence among men 5,6. Mucocele in the appendix may be classified according to the histological characteristics of lumen obstruction 7. Simple mucocele inflammatory, obstructive or retention cyst is characterized by degenerative epithelial changes and results in the obstruction and the distension of the appendix.
Mucocele of the appendix: appendectomy or colectomy?
There is no evidence of hyperplasia or mucosal atypia. In hyperplastic mucocele, the appendix muocele occurs due to the hyperplastic growth of appendieal appendix or cecal mucosa, just like hyperplastic polyps in the colon. In both types described, the mucus material contains epithelial adenoma cells with low or high grade of dysplasia. The rupture of the appendix may lead to the dissemination of the epithelium that produces mucins in the abdominal cavity, causing mucinous ascites or pseudomyxoma peritonei.
Out of these, were submitted to surgery and histological analyses, and 37 presented pseudomyxoma peritonei. Thus, both the benign and the malignant mucocele may cause pseudomyxoma peritonei, however, this complication is more frequent and has worse prognosis for malignant cases, probably because in this situation the appendix ruptures more easily, and the celular seeding is more aggressive 4,5, Mucocele of the appendix can also result from alterations in the cecum, such as fecal impaction, polyps or malignant neoplasms, which, in theory, can obstruct the appendiceal ostium.
Another rare cause found in literature is endometriosis, which may be established on the wall of the appendix, causing lumen obstruction 8. The classification based on histopathological standards is really important, once the progress of the disease and its prognosis are related to the subtypes.
Simple and benign mucoceles have an insidious evolution and are rarely perforated; on the other hand malignant mucocele evolution is faster, like in acute appendicitis, usually presenting as an organ perforation 4.
The diameter of the non-neoplastic mucocele simple and hyperplastic is smaller than the neoplastic mucocele cystadenoma and cystadenocarcinoma ; however, there is no difference related to size among benign and malignant neoplastic mucoceles. Besides, no neoplastic mucocele has a diameter smaller than two centimeters 4. The clinical presentation of mucocele in the appendix is usually unspecific, with difficult preoperative diagnosis.
The carcinoembryonic antigen CEA level at preoperative may suggest malignity in the appendix or in the colon 9, Imaging tests, such as ultrasound, computed tomography and enema, besides colonoscopy, may suggest the presence of mucocele of the appendix, which helps to define the treatment. The ultrasound shows an encapsulated cystic lesion in the lower quadrant of the abdomen with a liquid content of variable echogenicity, according to the density of the mucus Some tests present images of multiple echogenic layers in the dilated appendix, which may be considered as pathognomonic of appendix mucocele At computer tomography, the typical feature of mucocele of the appendix is a cystic mass with a thin wall and of low density, which communicates directly with the cecum Figure 1.
The presence of punctate or curvilinear calcification in this wall confirms the mucocele diagnosis and differs from the appendicular abscess, which does not have this characteristic 6.
At enema, the presence of mucocele can be characterized by a cecal filling defect, besides the lateral displacement of the cecum and terminal ileum Colonoscopy may show a soft erythematous mass, with a central crater due to the protrusion of appendiceal ostium, which can increase or decrease according to the respiratory movement This condition is known as “volcano sign” 16 Figure 2.
The cytology of the mucus inside the mucocele obtained by puncture with a thin needle may distinguish benign and malignant forms, but it should not be used due to the risk of cell dissemination and evolution to pseudomyxoma peritonei 18, The treatment of appendix mucocele is surgeryl and determined by some factors, such as the integrity of the wall of the organ, the dimensions of its base and histopathological examination of the cause of mucocele.
For mucocele Figure 3appendectomy with lymphadenectomy, including all the fat from the mesoappendix in the resection, is indicated for cases of simple or benign mucocele, when the appendicular base is not compromised by the dilation and is smaller than 2. The partial cecal resection with linear stapler cutter, including the site of implantation of the appendix, is performed in cases of mucocele with dilated appendicular base larger than 2.
This procedure prevents the dissemination of neoplastic cells to the abdominal cavity, besides ensuring a negative margin in the resection-line Figures 5 and 6. The release and exteriorization of the cecum should occur in order to reduce the risk of contamination in the abdominal cavity in cases of unwanted rupture during the manipulation of the cecal appendix.
In both surgical procedures, the cecal appendix is sent to frozen section. In case there is suspicion or detection of malignant neoplasm as the cause of mucocele, the resection is complemented with the right colectomy, with the objective of removing the whole lymphatic chain of the region. If the frozen section is not available at the time of the initial surgery, which is usually urgent, right colectomy should not be performed. If the lymph nodes are increased and the frozen section is positive for malignity, or even if the histopathological examination of the surgical piece confirms the malignant etiology, the patient is submitted to right colectomy.
Appendiceal mucocele | Radiology Reference Article |
However, when the patient undergoes colonoscopy at the preoperative and a malignant neoplasm is diagnosed in the cecum, or if a cecal tumor is noticed, right colectomy is the first choice. A complete abdominal exploration during intraoperative is indicated due to the occurrence of mucocele in synchrony with other tumors, like colon and ovaries.
This conduct is mainly indicated when the surgery is performed with urgency, and preoperative examinations are not made In cases of mucocele, lymphadenectomy in the mesoappendix is common to help the pathologist define the histology of the lesion. Besides, lymphadenectomy is important to define the conduct of other cecal appendix tumors, like carcinoid and adenocarcinoid tumors, which may eventually lead to mucocele 19, If the mucocele is simple and benign, appendectomy with lymphadenectomy is the definite treatment, as well as it mucoxele for carcinoid and adenocarcinoid tumors with favorable histology small, with negative and well differentiated lymph nodes and endometriosis.
If the histological diagnosis points to bowel muckcele mucinous adenocarcinoma, carcinoid or adenocarcinoid tumors larger than 2. Even though lymphatic dissemination is not so frequent in this type of tumor, the mucinous adenocarcinoma of the non-perforated appendix has higher chances of healing with the right colectomy.
This surgery has low mortality rates, especially when elective and performed in patients at a good general state 21, The bowel adenocarcinoma is always submitted to right colectomy because the incidence of lymphatic dissemination is high in this type of tumor The performance of appendectomy by videolaparoscopy in cases of mucocele is not indicated due to the manipulation and risk of appendicular rupture and the dissemination of mucus with the possibility of peritoneal implants In case mucocele is diagnosed during laparoscopy, the surgery muoccele be converted into a laparotomy.
However, some authors disagree as to the recommendation to avoid laparoscopy for mucocele, by saying that laparoscopic appendectomy to appendicwal appendix tumors has late results, similar to the open technique, in case there is a careful manipulation of the organ and the use of protective envelopes 25, However, although it is technically possible to remove the intact appendix with free resection margins with laparoscopy, the advantage of open surgery is the release and exteriorization of the cecum, avoiding the contamination of the cavity in case of accidental rupture of the appendix.
As to follow-up, a recent study suggests histological, clinical and genetic similarities in proliferative lesions of the appendix and colonic mucosa So, simple and hyperplastic mucoceles would not require follow-up, benign mucocele would be mucoceoe as an adenomatous polyp with colonoscopies, according to the follow-up of colonic adenomas 28and the malignant one would be followed-up as a colonic adenocarcinoma, with doses of CEA and serial colonoscopies In cases of perforated mucocele of the appendix Figure 7there is mucus extravasation to the abdominal cavity, the pseudomyxoma peritonei.
This entity was first described in by Werth 30and is characterized by implants of mucinous epithelium and mucus accumulation in the peritoneal cavity. The treatment depends on the histology of the appendix, the cytology of the ascitic fluid and the presence of positive lymph nodes in the mesoappendix 23, These patients may present an abrupt evolution, with symptoms that characterize acute appendicitis, or present chronic evolution, with an increased abdominal circumference, mucinous ascites, mucin within the hernia sac and ovarian tumor Computed tomography can show the ascitic fluid, changes in hepatic contour and presence of nodes in the splenic capsule, corresponding to peritoneal implants, calcification of serous implantations; besides, it can also show metastatic mucoecle carcinoma.
The initial surgery in cases of mucocele of the appendix is appendectomy, block resection of the appendicular fat and collection of mucinous ascitic fluid. In patients with free mucinous ,ucocele in the abdominal cavity, the peritoneum would work as a defense against the dissemination of epithelial cells.
Thus, the initial surgery should be as minimal as possible, in order to keep the peritoneum intact 23, Patients with perforated mucocele who did not present positive lymph nodes or compromised margins, and who undergo right colectomy, present lower survival rates when compared to those who are only submitted to appendectomy at the time of the primary surgery Cases of deep invasion into paracaval retroperitoneal tissues at right colectomy have been reported, which is different from the minor superficial aggression, usually observed in patients with pseudomyxoma peritonei and an intact peritoneum This conduct is different from the primary colon cancer with peritoneal carcinomatosis, in which the results are better when the muocele conduct is performed at the initial surgery However, if it is an adenocarcinoma of the intestine, or if the lymph nodes are positive as to malignity at the frozen section, right colectomy is performed at the initial surgery.
If the histopathological examination diagnoses bowel adenocarcinoma, the indication is right colectomy.
Mucocele of the Appendix: Case Report and Review of Literature
If it is mucinous, the colectomy is appndiceal if the lymph nodes of the appendicular fat are positive, and typhlectomy is indicated if the margins are compromised The lymphatic dissemination of the mucinous adenocarcinoma is rare, and the survival of these patients does not change when the bowel resection is magnified in cases in which the peritoneum is compromised The prognosis of patients with adenocarcinoma of the appendix is controversial, depending on histological type.
While some authors observe a better prognosis with bowel adenocarcinoma, others demonstrate more favorable results with the mucinous adenocarcinoma 27,35, As appendicel reported, any patient with benign or malignant mucocele of the appendix may have pseudomycoma peritonei, however, this condition is more common for the malignant mucocele 4,5. There is no such risk in simple mucocele, since there are no epithelial cells in the mucus.
Mucus cytology should be immediately performed, because the result will define surgical therapy. If the cytology of the mucinous ascitic fluid is negative for adenomatous epithelial cells, the indication is hyperthermic intraoperative intraperitoneal chemotherapy. If it is positive, besides the operative chemotherapy, the cytoreductive surgery and postoperative intraperitoneal chemotherapy are performed The cytoreductive surgery and intraperitoneal chemotherapy are indicated for patients with the disease appendjceal to the peritoneum, with curative intent.
This procedure is not recommended at the presence mucoecle unresectable malignant liver or distant disease. Mucocfle surgery consists of trying to resect all visible peritoneal implants or, if it is not possible, of leaving only implants smaller than 2.