Mucocele of appendix with an elevated carcinoembryonic antigen: A case report.

Abstract

Mucocele of the appendix is an uncommon disease in which there is cystic dilatation of the appendix caused by mucus secretion and usually associated with benign or malignant causes. Preoperative diagnosis is difficult as the patient presents with non-specific clinical symptoms. We report a case of mucocele of the appendix with elevated serum carcinoembryonic antigen (CEA) - a condition sparsely reported in literature. Patient presented with pain in the right iliac fossa for 7 months. On exploration, a cystic mass of the appendix without perforation was found in right iliac fossa. There was no lymph nodes enlargement. Appendicectomy was performed with subsequent normalization of CEA level and histopathology confirmed the diagnosis of mucinous neoplasm of the appendix. Patient is feeling well after one year of follow up.

Introduction

Appendiceal mucocele is the cystic dilatation of the vermiform appendix, caused by intraluminal accumulation of mucinous material. This unusual disease of appendix is found in 0.2-0.6% of all appendectomies1. Mucocele of appendix was first described in 1842 by Rokitansky2. It is more frequent among individuals aged 50 years or more while gender prevalence is controversial3. There are four histological types: retention cyst, mucosal hyperplasia, mucinous cyst adenoma, and mucinous cystadenocarcinoma.1 A Consensus for classification and pathologic reporting of Pseudomyxoma Peritonei and associated appendiceal neoplasia was developed by the results of the Peritoneal Surface Oncology Group International (PSOGI) and it was agreed that the term "low-grade appendiceal mucinous neoplasm" was supported and "cystadenoma" should no longer be recommended4.

There is no typical clinical picture of the disease as most patients present with non-specific symptoms like pain in right iliac fossa; therefore preoperative diagnosis is difficult as surgeons tend to mistake it for acute appendicitis. Ultrasound, CT scan and colonoscopy are helpful in preoperative diagnosis. Treatment is always surgical. Prognosis is good if structural integrity of appendix is preserved. If appendix has perforated secondary to mucocele with extravasation of contents in abdominal cavity then pseudomyxoma peritonei can occur which poor prognosis has if not properly and promptly treated. In a patient presenting with right iliac fossa mass, pathology of appendiceal origin should be considered in differential diagnosis. Carcinoembryonic antigen (CEA) levels should be correlated with radiological findings in case of mucinous neoplasm of appendiceal origin5.

Case Reports

A 53 years old salesman presented with pain in the right lower abdomen for 7 months associated with dyspepsia and anorexia for 6 months. The bowel habits were irregular but no bleeding per rectum. The patient was a known hypertensive with good control for 3 years.

On examination, his general condition appeared satisfactory. On abdominal examination, a firm, mobile and non tender mass was palpable in right iliac fossa measuring about 11×5cm. Digital rectal examination was unremarkable and his haematological investigations were within normal range.

Ultrasound of the abdomen and pelvis showed a large oval well demarcated mass lesion measuring about 12x3.5cm in size was seen in the right iliac fossa. (Fig. 1) The lesion was associated with an abnormally dilated gut segment with thick intraluminal debris and some solid component and the typical onion skin appearance suggestive of appendix mass or mucocele. CEA level of the patient was raised 13.2 ng/mL.

Fig. 1. Ultrasound showing mass in right iliac fossa.

CT scan abdomen and pelvis with contrast was done which revealed a well-defined low density featureless tubular structure visualized in right iliac fossa. The lesion showed fluid density with minimal wall enhancement. There was no evidence of any soft tissue or calcified lesion within or adjacent to this lesion; the caecum and rectum showed no evidence of wall thickening or solid lesions. No abdominal lymphadenopathy and free fluid was seen in peritoneal cavity. Features were suggestive of mucocele of appendix (Fig. 2)

Fig. 2. CT scan showing featureless tubular structure in right iliac fossa.

On colonoscopy, a globular mass was seen indenting the caecum with hyper vascular smooth surface and margins suggestive of a benign ceacum mass. On exploration, there was a huge dilated appendix of about 12x5 cm filled with yellow thick mucous fluid (Fig. 3) with clear margin of a normal looking caecum. There was no lymph node enlargement or peritoneal fluid. Appendicectomy was performed. (Fig. 4) and postoperative recovery was uneventful.

Fig. 3. Peroperative finding showing a distended tubular appendix.

Fig. 4. Postoperative specimen.

Histopathology report confirmed the lesion to be a low grade mucinous appendiceal cystadenoma with clear resection margins which were uninvolved by the tumor. Additional pathological findings were extravasated mucin with epithelial cells, diverticula formation and plasma cells infiltrating the wall of appendix. (Fig. 5) CEA levels were repeated one week after surgery which dropped to 2.37ng/mL. At one year follow-up the patient was symptom free.

Fig. 5. Histopathological features of Low grade appendiceal mucinous neoplasm. A: Mucin rich epithelium with goblet cells (H&E, 20x). B: Diverticulum-like growth with thinned appendiceal wall (H&E, 10x). C: Undulating mucosal growth with loss of lamina propria and muscularis mucosae & submucosal fibrosis (H&E, 20x).

Discussion

The mucocele of appendix was first described in 1842 by Rokitansky2and characterized in 1973 by Aho et al6 with the term retention cyst to describe a sterile outflow obstruction in the appendix that was dilated and swollen by glary mucus. Mucocele of appendix accounts for about 0.3% of appendix specimens, with mucinous cystadenoma being the most commonly encountered appendiceal mucoceles1. Mucoceles that are less than 2 cm in diameter are usually simple retention cysts, while hyperplastic epithelium, cystadenoma and cystadenocarcinoma are more likely to be greater than 2cm1.

Appendix mucocele may arise as a consequence of obstructive or inflammatory processes associated with cystadenoma or cystadenocarcinoma. Mucocele of the appendix may be due to cystadenoma in 63% of cases, cystadenocarcinoma in 11%), mucosal hyperplasia or inflammatory process in 25% and infrequently due to lumen obstruction by carcinoid tumors or endometriosis1. Besides these causes, other tumor lesions in the appendix or caecum may present as mucocele. Mucinous cystic adenoma is an unusual cystic neoplasm of the vermiform appendix with villous adenomatous changes in appendiceal epithelium associated with mucin filled lumen. As per the consensus of the Peritoneal Surface Oncology Group International (PSOGI) in 2016, our pathologist also reported this as low grade mucinous neoplasm of the appendix.4

The clinical presentation of the disease does not have a typical picture. Most common presentation is right iliac fossa pain, similar to that of acute appendicitis or palpable abdominal mass associated with nausea or vomiting however, about 25% patients are asymptomatic and the condition is found incidentally on imaging or at the time of surgery1. The index patient presented with pain in the right iliac fossa for last seven months associated with dyspepsia and anorexia but no rectal bleeding. Also there was a palpable non tender mass in right iliac fossa mimicking the suspicion of colonic pathology.

Preoperative diagnosis of appendicular mucocele is important for the selection of a proper surgical procedure to prevent its complications. Ultrasonography, CT scan and colonoscopy are helpful diagnostic tools. Ultrasound is the first investigation of choice used for diagnosis in patients with abdominal pain that can differentiate between mucocele appendix and acute appendicitis. CT scan is more accurate that is used to identify the specific features of mucocele of the appendix with high accuracy which includes appendix lumen of more than 1.3 cm, its cystic dilatation, and wall calcification. Colonoscopy might show an elevation of the appendiceal orifice with a yellowish mucous discharge from the orifice. In our patient, ultrasound findings were also suggestive of appendicular mass or mucocele. Absence of acute pain and fever raise the index of suspicion in this case. CT and colonoscopy were indispensable in diagnosis. Elevated serum CEA level requires careful investigations to exclude malignancy.

Adequate operative treatment of simple cystadenoma is appendicectomy7. In our patient the mucocele was not perforated, there was no pathological process in the base of the appendix and the regional lymph nodes were negative. Therefore, only appendicectomy was performed that is an adequate surgery in such a case.