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LETTER TO EDITOR Table of Contents   
Year : 2001  |  Volume : 11  |  Issue : 1  |  Page : 42-43
Mucocele of appendix

Department of Radiodiagnosis, MD Oswal Cancer Treatment and Research Foundation, Ludhiana, India

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How to cite this article:
Garg L, Gupta A, Gupta A, Shrimali R. Mucocele of appendix. Indian J Radiol Imaging 2001;11:42-3

How to cite this URL:
Garg L, Gupta A, Gupta A, Shrimali R. Mucocele of appendix. Indian J Radiol Imaging [serial online] 2001 [cited 2020 Apr 10];11:42-3. Available from:
Dear Sir,

A fifty-three-years old, previously healthy man presented with vague abdominal discomfort and distension of several weeks' duration. Physical examination revealed a smooth, non-fluctuating mass occupying the whole of the right lower abdomen. The borders of the mass were well defined. The mass was not mobile.

US revealed a cystic mass occupying the right lower abdomen. CT exhibited an elongated cystic mass measuring about 10.0x5.0 cms centered in the right iliac fossa, medial to the cecum. Its wall showed arcs of calcification. The contents of the mass appeared to resemble thick fluid [Figure - 1]. Inhomogeneous opacification of the greater omentum and free fluid were seen in all the peritoneal compartments [Figure - 2]. A few soft tissue attenuation nodules were also discernible on the parietal peritoneum [Figure - 3]. Bilateral pleural effusions were also noted.

Based on these imaging findings, a CT diagnosis of mucocele of the appendix with pseudomyxoma peritonei was made. In view of the peritoneal deposits, including smudging of the omentum, a diagnosis of mucinous cystadenocarcinoma of the appendix was suggested.

At laparotomy, a smooth cystic tumor adherent to the medial wall of the cecum was found. Multiple metastatic deposits were seen over the peritoneal surfaces including the mesentery and omentum. Thick gelatinous ascitic fluid was also present. The final histopathological diagnosis was mucinous cystadenocarcinoma of the appendix with pseudomyxoma peritonei. The patient underwent a right hemicolectomy and was later put on chemotherapy.

Mucoceles of appendix are characterized by accumulation of mucoid material in the appendix. Mucinous cystadenoma and cystadenocarcinoma comprise most of the cases [4]. The neoplastic mucocele and retention cysts are clinically and radiologically difficult to differentiate, but malignant mucoceles have additional findings [3],[4],[5].

The clinical presentation of a mucocele is usually non-specific and up to fifty percent are discovered incidentally at surgery [5]. CT can play an important role in pre-operative diagnosis. The classical CT findings are:

  1. A cystic, well-encapsulated round or ovoid mass centered in the right iliac fossa.
  2. Mural calcification.
  3. Absence of periappendiceal inflammation or abscess [4],[5]

Adequate opacification of the terminal ileum and cecum is essential for optimal examination. Pseudomyxoma peritonei is characterized on CT by the presence of low attenuation ascites with scalloping of liver contour due to peritoneal implants. Implants can also be seen on the visceral surfaces and as nidi within cavities. These nodules may show calcification usually in a rim like fashion. Scalloping of the liver contour was not seen in our patient, highlighting the fact that absence of scalloping does not rule out pseudomyxoma peritonei. Loculation of ascitic fluid with associated mass effect should also lead to a consideration of pseudomyxoma peritonei.

The pathophysiology of pseudomyxoma peritonei is a matter of controversy; some have considered it a foreign body peritonitis with a fibrotic response caused by spillage of mucous into the peritoneum [3]. However, some studies indicate that pseudomyxoma occurs only in the presence of malignant mucoceles. When pseudomyxoma peritonei is found in the setting of cystadenocarcinoma of appendix, the prognosis is poor, with a twenty-percent five-year survival rate [3].

Pseudomyxoma peritonei is also known to develop from ovarian cystadenocarcinoma. In these patients a mucinous neoplasm of the appendix is also nearly always present. Whether the ovarian and appendiceal tumors represent independent primary tumors or whether the ovarian tumors are secondary to appendiceal tumors remains a controversy. Both tumors are usually synchronous, but one may appear many years after the removal of the other. Mucinous cystadenocarcinomas arising from the urachus, uterus or omphalomesenteric duct are also known to cause pseudomyxoma peritonei.

The differential diagnosis of mucocele of the appendix includes mesenteric cyst, duplication cyst, right ovarian cyst and hydrosalpinx.

To conclude, the CT findings of a cystic mass in the right iliac fossa, adherent to the cecum, in a patient who has not undergone appendectomy, are highly suggestive of mucocele of appendix. Presence of mural calcification can be a valuable clue to the diagnosis. The presence of low attenuation ascites with peritoneal implants is suggestive of associated pseudomyxoma peritonei. Scalloping of the visceral surfaces, although considered diagnostic, may not always be seen.

   References Top

1.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. 1    
2.Higa E, Rosai J, Pizzimbaro CA et al. Mucosal hyperplasia, mucinous cystadenoma and mucinous cystadenocarcinoma of the appendix. Cancer 1973; 32: 1525-1541.   Back to cited text no. 2    
3.Dachman AH, Leichenstein JE, Friedman AC. Mucocele of the appendix and pseudomyxoma peritonei. AJR 1985; 144: 923-929.   Back to cited text no. 3    
4.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. 4  [PUBMED]  [FULLTEXT]
5.Isaacs KL, Warshauer DM; Mucocele of the appendix; computed tomographic, endoscopic and pathologic correlation. Am. J. Gastroenterol, 1992; 87: 787-789.  Back to cited text no. 5    

Correspondence Address:
L Garg
Department of Radiodiagnosis, MD Oswal Cancer Treatment and Research Foundation, Ludhiana
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Source of Support: None, Conflict of Interest: None

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[Figure - 1], [Figure - 2], [Figure - 3]


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