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ABDOMINAL IMAGING Table of Contents   
Year : 2003  |  Volume : 13  |  Issue : 1  |  Page : 33-34
Case report : High resolution ultrasonographic diagnosis of mucocele of the appendix

Dept. of Radiodiagnosis, G.R. Medical College and AJ Group of Hospitals, Gwalior-474009, MP, India

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Keywords: Mucocele Appendix, High Resolution Ultrasonography

How to cite this article:
Yadav P, Mukherjee S, Slkarwar J S, Sharma G L. Case report : High resolution ultrasonographic diagnosis of mucocele of the appendix. Indian J Radiol Imaging 2003;13:33-4

How to cite this URL:
Yadav P, Mukherjee S, Slkarwar J S, Sharma G L. Case report : High resolution ultrasonographic diagnosis of mucocele of the appendix. Indian J Radiol Imaging [serial online] 2003 [cited 2021 Feb 28];13:33-4. Available from:

   Case Report Top

A 25 year old female presented with poorly localized abdominal pain and distension for two weeks. The pain wasn't associated with nausea, vomiting diarrhea, constipation or any other complaints. On direct questioning the patient stated that she had a severe episode of periumbilical pain about two months back for which she was admitted and received some sort of medication which resulted in symptomatic relief. The examination of the abdomen revealed a smooth tender fluctuant mass in the right lower quadrant. The mass was not mobile. The patient had mild fever and her white blood cell count was yet to be determined. A tentative diagnosis of an appendicular mass was made.

Transabdominal high resolution ultrasound was done using a Wipro GE Pro 400 Series with a high frequency 8.2 MHz linear probe. The appendix measured 15 mm in AP diameter and 38 mm in length. The appendiceal surface appeared smooth and thin in outline. The appendix appeared as a cystic anechoic mass with posterior acoustic enhancement [Figure - 1]. There were few mobile foci of inflammatory debris inside the lumen. The mucosa of the appendix appeared intact, hyperplastic with minimal inflammation. No hyperechoic foci or any calcification was visible [Figure - 1]. The sonographic diagnosis was confirmed intraoperatively as well as on histopathology postoperatively.

   Discussion Top

Mucoceles of the appendix are rare, appearing in 0.2-0.3% of surgical appendectomy specimens. They are pathologically divided into 4 categories. A very rare type is secondary to occlusion of the lumen from post-inflammatory scarring, progeric atrophy, congenital obstruction of Gerlach's valve or extramural compression. This type leads to atrophic mucosa. All other types are classified into a spectrum from mucous hyperplasia to mucinous cystadenoma to mucinous cystadenocarcinoma depending on the pathology of the mucosa. Whatever the cause, obstruction of the lumen and accumulation of yellow mucous within the appendiceal lumen result. About 25% of mucoceles are from mucosal hyperplasia. These typically have minimal distention. Mucinous cystadenomas, which account for about 60% of mucoceles, are more markedly distended. However, they are typically asymptomatic, and found incidentally. Mucoceles up to 40 x 24 x 20 cm have been reported. About 20% have extra-appendiceal extrusion of mucus. If no cells are present in this peritoneal mucous, the prognosis is excellent. Mucinous cystadenocarcinomas (10.15% of cases) are more likely symptomatic-this diagnosis is made by either neoplastic glands invading the wall or by the presence of cells in the peritoneal mucous. It is thought by some that pseudomyxoma peritonei is a complication of only mucinous cystadenocarcinoma. However, other authors believe this can complicate either benign or malignant mucoceles although pseudomyxoma peritonei from the former would carry a better prognosis. [1],[5],[6].

Mucinous cystadenocarcinomas are extremely rare (benign: malignant about 10:1), but are believed to arise in cystadenomas, and there is a high correlation of synchronous or metachronous colorectal adenomas and carcinomas (up to 20% in two series). There have also been reports of association with gastrointestinal tract, ovary and kidney tumors. It is thought that only mucinous cystadenocarcinomas lead to pseudomyxoma peritonei [5].

A very important fact to be stressed here is the need for more Mucoceles of the Appendix to be diagnosed preoperatively. This makes the surgeon aware of the need for more careful surgery and consequently reduces the chances of iatrogenic damage to a Mucocele with resultant leakage of the contents in the abdominal cavity with serious repercussions especially pseudomyxoma peritonei [4].

On sonography, there is typically excellent through-transmission and posterior wall enhancement. When the wall is calcified, posterior acoustic shadowing may occur, but often cannot be appreciated. The wall thickness varies, but if the wall is greater than 6mm, one should also consider uncomplicated acute appendicitis. The internal features vary from anechoic to hyperechoic, and may be dependent. Internal septations, polypoid lesions extending into the lumen and irregular shapes seem to be associated with the malignant variety, although some papillary processes may be seen in mucinous cystadenomas [3],[5],[8].

On CT, typically it is a low-attenuation (0-40 H) smooth or lobulated mass. The more complex and irregularly shaped mucoceles tend to be mucinous cystadenocarcinomas. They may have simple or multiple cystic components and some solid elements. These may even demonstrate infiltration into adjacent organs such as the colon, bladder and ureter. Attenuation is near that of water. Curvilinear or punctuate calcification in the lesion is strongly suggestive of mucinous cystadenoma (yellow arrow), and this is often not seen on plain films. Amorphous calcifications may be seen in the malignant type. This is from chronic inflammatory process incited by the irritating mucous. Vertical folds (red arrow), mimicking intussusception, have also been described. A pitfall is that the fluid filled terminal ileum may resemble a mucocele, so delayed scanning may be warranted in some cases [2],[7].

The finding of an appendiceal mucocele should prompt a search for an associated tumor-6-fold increased incidence of colon adenocarcinoma and there may be association with mucin-secreting tumors of the ovary. [4]

On a final note, in the differential on USG in a right lower quadrant mass one must consider a fluid filled small bowel, fluid in small or large bowel diverticulum, appendiceal/diverticular abscess, mesenteric cyst seroma and particularly in females of reproductive age group salpingitis and ectopic pregnancy masses [3],[4].

   References Top

1.Hagen-Ansert, S, Textbook of Diagnosis Sonography 5th ed. Vol 1. Mosby: St Louis, 2001  Back to cited text no. 1    
2.Kim SH, Lim HK, Lee WJ, Lim JH, Byun JY. Mucocele of the appendix: ultrasonographic and CT findings. Abdominal Imaging 1998; 23: 292-296.  Back to cited text no. 2  [PUBMED]  [FULLTEXT]
3.Degani S, Shapiro I, Leibovitz Z etal. Sonographic Appearance of Appendiceal Mucocele. J Ultrasound Obstet Gynecol 2002: 19(1):99-101.  Back to cited text no. 3    
4.Chen SC, Chem KM, Wong SCm, et al. Abdominal Sonography Screening of Clinically Diagnosed Suspected Appendicitis Before Surgery. World J Surg 22:449-452, 1998.  Back to cited text no. 4    
5.Aho AJ, Heineman R, Lauren P. Benign and malignant mucocele of the appendix. Acta Chir Scand. 1973; 139: 392-400.  Back to cited text no. 5    
6.Higa E, Rosai J, Pizzimbono C, et al. Mucosal hyperplasia, mucinous cystadenoma, and mucinous cystadenocarcinoma of the appendix: A re-evaluation of appendiceal "mucocele." Cancer 1973: 139:392-400.  Back to cited text no. 6    
7.Balthazar, Email J, Computed Tomography of the Abnormal appendix, Journal of Computer Assisted Tomography, 12(4):595-601, July/August 1988.  Back to cited text no. 7    
8.Madwed D, Mindelzun R, and Jeffrey RB Jr. Mucocele of the Appendix: Imaging Findings. AJR 159:69-72, July 1992.  Back to cited text no. 8    

Correspondence Address:
P Yadav
C-27, Jawahar Colony, Kampoo, Gwalior, M.P-474009
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[Figure - 1]

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