Clinical History
An 82-year-old female patient presented with fever, nausea, vomiting and pain in the right flank. Her medical history showed that she had undergone a total hysterectomy and bilateral adnexectomy 40
years ago. The laboratory findings showed an elevated sedimentation and white blood cell count. An ultrasonographic examination of the abdomen showed the presence of a 10 cm large thick-walled cystic
mass with a slightly hyperechogenic and heterogeneous content. A discrete vascularization of the wall of the cystic mass was seen. A Computed Tomography (CT) examination of the abdomen was performed.
It was found that the large cystic mass was located against the cecum, displaying discrete enhancement of the cystic wall with a small amount of air and oral contrast agent in its lumen. A right
hemicolectomy was performed. The pathologic examination of the resected specimen was conclusive.
Imaging Findings
An 82-year-old female patient presented with fever, nausea, vomiting and pain in the right flank. Her medical history showed that she had undergone a total hysterectomy and bilateral adnexectomy 40
years ago. The laboratory findings showed a sedimentation level of 89 mm/h and white blood cell count of 14.100/mm³. An ultrasonographic examination of the abdomen showed the presence of a 10 cm
large thick-walled cystic mass with a slightly hyperechogenic and heterogeneous content (Fig. 1). A discrete vascularization of the wall of the cystic mass was seen. Differential diagnosis included
an acute appendicitis with abcedation, a mucocele of the appendix (with suspicion of an underlying tumor regarding the age of this patient), a duplication cyst, a mesenteric cyst or a congenital cyst
with internal hemorrhage. A tumoral process of the ovaries was not included in the differential diagnosis because of the medical history of this patient. A Computed Tomography (CT) examination of the
abdomen was performed in the venous phase, after the administration of an intravenous contrast material. It was found that the large cystic mass was located against the cecum, displaying discrete
enhancement of the cystic wall(Fig. 2). A small amount of oral contrast agent (Fig. 3) was seen together with a delicate amount of air (Fig. 4) in the lumen of the cystic mass. A limited inflammatory
reaction in the surrounding mesenteric fatty tissue was noted. No ascites was present neither were lymphadenopathies visualized. A right hemicolectomy was performed. The pathologic examination of the
resected specimen (Fig. 5) was conclusive.
Discussion
Primary appendiceal neoplasms are uncommon, and comprise approximately 0.5%–1% of appendiceal neoplasms (3). The most important differential diagnoses include epithelial tumors, carcinoid
tumors, lymphomas and very rare tumors such as ganglioneuroma, pheochromocytoma, Kaposi sarcoma and mesenchymal tumors (2). These tumors occur in the middle-aged or older patients, except the
carcinoid tumors, which occur in young adults. Thirty to fifty percent of all appendiceal neoplasms will clinically present with signs and symptoms of acute appendicitis (3). Carcinoid neoplasms are
the most common neoplasms found in the appendix (1). The incidence of carcinoid tumor is 0.32% and 0.054% in surgically removed appendices and in autopsy series respectively (1). This endocrine tumor
originates from subepithelial neuroendocrine cells (2). Classic carcinoid tumors make up to 80% of all neoplasms of the appendix (2). Mucocele formation may occur, but is a rare finding (2).
Epithelial neoplasms of the appendix are either benign or malignant (2). These neoplasms are less common than carcinoid tumors but are more often diagnosed by imaging due to their large size (2). A
mucocele is a macroscopic descriptive term which means that the appendix is grossly distended by mucus. It can be caused by a variety of non-neoplastic, benign neoplastic, and malignant conditions
(2). They are mostly found incidentally, because a mucocele results from a chronical luminal obstruction (2). The imaging diagnosis of neoplasms hinges primarily on detection of the resulting
mucocele. An abdominal radiography may suggest the presence of a soft-tissue mass in the right lower quadrant, but is mostly aspecific. At ultrasound (US), an ovoid cystic mass, with or without
acoustic shadowing from dystrophic mural calcification, is characteristic of mucoceles from mucinous neoplasms. The intraluminal ultrasonographic texture can have a variable appearance but
hypo-echoic internal echoes are somewhat typical. The differential diagnosis might also include peri-appendiceal abscess, enteric duplication cyst, mesenteric cyst and hydrosalpinx (2). An additional
CT scan can be useful for evaluating a mucocele of the appendix. The anatomic relationship between the elongated cystic mass and the cecum can be more apparent at CT than at US. Furthermore, CT is
more sensitive than radiography in detecting mural calcifications. However, inadequate opacification of the ileocecal region with enteric contrast material is a well known cause of false-positive and
–negative findings at CT (2). The difference in the frequency of a tumor manifesting as appendicitis, between mucinous neoplasms and all other appendiceal neoplasms, is significant (P<0.001)
(3). At an older age, in the case of appendiceal pathology, the possibility of an underlying malignancy must be excluded. The frequency of carcinoma ‘masquerading’ as appendicitis is
likely to increase with age (3). Preoperative imaging is of importance as it can direct the surgeon in performing an appendectomy or right hemicolectomy, laparoscopically or by performing a
laparotomy, if indicated. The CT findings strongly suggest the presence of an underlying neoplasm in the majority of patients (3). Our patient had a bilateral adnexectomy 40 years ago, rendering the
possibility of a mucinous tumoral pathology of gynecological origin unlikely. In this case, the additional CT examination following the US examination was useful. The opacification of the lumen of
the cystic mass by orally ingested contrast material allowed a better insight into the anatomic relationship between the cystic mass and the cecum. Although in this case all radiological examinations
were unable to visualize the tumoral mass itself, the additional CT examination was important in the decision-making to operate on the patient. Suggestion of an underlying tumor was made because of
the age of this patient. Therefore, the decision was made to perform a right hemicolectomy. The pathological examination revealed the presence of a mucinous adenocarcinoma of the appendix, causing
the mucocele.
Differential Diagnosis List
Mucinous cystadenocarcinoma of the appendix.
Final Diagnosis
Mucinous cystadenocarcinoma of the appendix.
