CASE 761 Published on 12.12.2000

Mucinous cystadenoma of the appendix

Section

Abdominal imaging

Case Type

Clinical Cases

Authors

L. Thanos, A. Patsalides

Patient

63 years, female

Categories
No Area of Interest ; Imaging Technique CT
Clinical History
A 63year old female was admitted to the hospital for right lower quadrant (RLQ) pain, as well as for diarrhea and increased frequency of bowel movement.The clinical examination reveled tenderness and a palpable mass in the RLQ.
Imaging Findings
The patient was admitted to the hospital for right lower quadrant (RLQ) pain, as well as for diarrhea and increased frequency of bowel movement. The clinical examination reveled tenderness and a palpable mass in the RLQ. The complete blood count examination and urinalysis were normal. She has never been admitted to a hospital before nor she had received any medication in the past. A bowel enema was initially performed and a smooth, sharply defined extramucosal mass was found, impressing the apex of the cecum. The appendix was non filling. The differential diagnosis included an inverted appendiceal stump, acute appendicitis with abscess or cecal carcinoma. Abdominal Computed Tomography findings included a sharply defined round mass in the right lower quadrant. The central part of the lesion has low attenuation values. The wall of the lesion is thickened. Calcifications in the wall are clearly demonstrated.
Discussion
The benign mucinous cystadenoma is the most common mucinous neoplasm of the appendix. Yet, it is a rare tumor. It is associated with cystic distention of the appendix due to mucus production. Due to the distention of the viscous pain may be the presenting symptom as well as the increased frequency of bowel movements. In 20% of the cases, the appendix is perforated resulting in localized collections of mucous lying free in the peritoneal cavity or attached to the serosa of the appendix. Torsion resulting in gangrene is a potentially serious complication. Granuloma formation is another possible complication. Granuloma may be formed in adjacent tissues due to mucin expelled from the appendix. In these cases the differentiation from mucinous adenocarcinoma is difficult. A rare manifestation is appendiceal intussusception. The mucinous cystadenoma of the appendix may show an atypical presentation and it should be considered in the differential diagnosis of the right adnexal mass in a patient without previous appendectomy. Radiographically it presents as a globular, broad based mass invaginating into the cecum. It is associated with non-filling of the appendix. Peripheral rimlike calcifications are frequent. Computed tomography demonstrates a sharply defined round mass of homogenous content of near water or soft tissue density. Calcifications in the wall might also be demonstrated. On ultrasound it appears as a purely cystic mass, a cystic mass with fine echoes or as a complex cystic mass with high level echoes. Mucinous cystadenoma and mucinous cystadenocarcinoma may be indistinguishable grossly. Both contain mucus secreting epithelial cells with varying degrees of atypia and papillary configuration. The wall of the appendix becomes thin, ulcerated and calcified due to the overproduction of mucus. Mucin eventually penetrates the wall and appears in the periappendiceal and retroperitoneal areas. The histologic features that distinguish mucinous cystadenoma and mucinous cystadenocarcinoma is the invasion of the wall by atypical glands and the presence of epithelial cells in intraperitoneal mucinous collections. This distinction is important since adenomas are cured by simple appendectomy while adenocarcinomas are treated by right hemicolectomy.
Differential Diagnosis List
Mucinous cystadenoma of the appendix.
Final Diagnosis
Mucinous cystadenoma of the appendix.
Case information
URL: https://eurorad.org/case/761
DOI: 10.1594/EURORAD/CASE.761
ISSN: 1563-4086