闌尾粘液囊腫呈現為急腹症或急性闌尾炎的回顧性研究

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1 Hong Kong Journal of Emergency Medicine A retrospective study on mucocele of the appendix presented with acute abdomen or acute appendicitis 闌尾粘液囊腫呈現為急腹症或急性闌尾炎的回顧性研究 S Yakan, C Caliskan, A Uguz, MA Korkut, A Çoker Objective: We reported the demographic, clinical, radiologic, preoperative and postoperative characteristics and outcomes on patients of appendix mucocele that presented with or operated for acute appendicitis or acute abdomen. Methods: A retrospective study. Patients who were presented or operated for acute appendicitis or acute abdomen and had an operative histopathological diagnosis as appendix mucocele (simple mucocele, mucinous cystadenoma, mucinous cystadenocarcinoma) were included. Demographic, clinical, radiologic, preoperative and postoperative data of eligible cases were evaluated. Results: From January 2003 to February 2010, a total of 2120 patients with the pre-operative diagnosis of acute appendicitis were treated in our center, and nine (0.42%) patients were diagnosed to have mucocele of the appendix. Seven patients (78%) were female. Average age of the patients was 59.5 (range=25-74). Major complaint was right lower quadrant pain in eight (89%) patients. In preoperative ultrasonographic examination of the patients, appendiceal cystic masses (mucocele) were diagnosed in four (44.5%) patients. In histopathologic examination, the number of patients diagnosed to have simple mucocele was two (22%), mucinous cystadenoma was four (45%), and mucinous cystadenocarcinoma was three (33%). No postoperative morbidity or mortality was noted. Conclusion: Appendix mucocele is a rare disease and it is usually diagnosed histopathologicaly in appendectomy specimens. When a cystic mass in appendix is seen during operation, appendiceal mucocele should be kept in mind to avoid iatrogenic perforation causing pseudomyxoma peritonei and possible concomitant malignancies should be searched. (Hong Kong j.emerg.med. 2011;18: ) 目的 : 我們報告了闌尾粘液囊腫病人在人口統計學 臨床 放射學 術前和術後的特點和結果 方法 : 回顧性研究 本研究包括所有呈現為急腹症或急性闌尾炎的病人, 條件是手術組織病理診斷為闌尾粘液囊腫 ( 簡單的粘液囊腫, 粘液性囊腺瘤, 粘液性囊腺癌 ) 合資格病人的人口學, 臨床, 放射學, 術前和術後的數據, 我們會進行評估 結果 : 從 2003 年 1 月至 2010 年 2 月, 我們中心共有 2120 例術前診斷為急性闌尾炎的個案, 九名患者 (0.42%) 被診斷患有闌尾粘液囊腫 七名病人 (78%) 為女性 患者平均年齡為 59.5 歲 ( 值域 25-74) 八名患者 (89%) 主訴是右下腹疼痛 術前超聲檢查, 四名患者 (44.5%) 的診斷為闌尾囊性腫塊 ( 粘液囊腫 ) 病理組織學檢查, 病人確診為兩例 (22%) 簡單的粘液囊腫, 四例 (45%) 粘液性囊腺瘤, 和三例 (33%) 粘液性囊腺癌 術後無併發症或死亡的情形 Correspondence to: Savas Yakan, MD The Ege University, School of Medicine, Department of General Surgery, 9207 Sokak No:4 D:2 Maliyeciler Sitesi Karaba lar/ Izmir, Turkey savasyakan@gmail.com Cemil Caliskan, MD Alper Uguz, MD Mustafa Ali Korkut, MD Ahmet Çoker, MD

2 Yakan et al./mucocele of the appendix 145 結論 : 闌尾粘液囊腫是一種罕見的疾病, 它通常是從手術闌尾標本做出組織病理診斷 在手術過程中發現一闌尾囊性腫塊時, 應該考慮可能為闌尾粘液囊腫, 以避免醫源性穿孔導致假性腹膜粘液瘤, 並應搜索其他同時存在的惡性腫瘤 Keywords: Appendiceal neoplasm, mucinous cystadenoma, mucinous cystadenocarcinoma 關鍵詞 : 闌尾腫瘤 粘液性囊腺瘤 粘液性囊腺癌 Introduction Mucocele is a rare pathology of the appendix, characterised by a cystic dilatation of the lumen, with stasis of mucus inside it. The incidence ranges between 0.2% and 0.3% of all appendectomies, with higher frequency in the females (female to male ratio of 4:1) and in people older than 50 years old. 1 Most of these tumours are asymptomatic and found incidentally. 1 Others become symptomatic because of inflammation, for example, acute appendicitis or as a cause of nonspecific abdominal pain. Preoperative colonoscopy, ultrasonography (US), and computed tomography (CT) are useful methods in diagnosing mucocele and distinguishing the mucocele from mimicking diseases. 2 However, the diagnosis is usually made intraoperatively or postoperatively on histopathological examination. 3 A correct diagnosis may help to avoid iatrogenic rupture during surgery. Pseudomyxoma peritonei is the worst complication, characterised by peritoneal dissemination caused by spontaneous or iatrogenic perforation of the appendix, which has a high rate of morbidity and mortality. 4 We aimed to study the clinical and epidemiological characteristics of a series of mucocele patients who were presented as acute appendicitis or acute abdomen. Method This was a single centre retrospective study at The Ege University Faculty of Medicine, Department of Surgery. During the study period of January Februar y 2010, patients with the diagnosis of appendiceal mucocele were searched from the hospital electronic database using International Classification of Disease 10th revision (ICD-10) codes. At the first step, we searched patient list for ICD-10 code K35. At the second step, we separated these patients as malignant and benign neoplasms of the appendix by using ICD 10 codes C18.1 and D12.1, respectively, from the hospital electronic database system. Patients were evaluated for age, sex, symptom duration, major complaint, ultrasonographic and computed tomographic findings, surgical procedure performed, pathologic diagnosis and their follow up outcomes. Two trained reviewers independently double extracted the data into standard data collection sheets and any differences were resolved by consensus. The results were uploaded into excel files and statistical calculation were done using SPSS 15.0 software. Results Between January 2003 and February 2010, a total of 2120 patients with the preoperative diagnosis of acute appendicitis were treated in our centre. Of them, nine (0.42%) patients had mucocele of the appendix. Average age of the patients in years was 59.5 (25-74). Seven (78%) of the nine patients were female, two (22%) were male. The duration of the symptom was variable, between 1 day and 3 months, with a median of 5 days. Major complaint in eight (89%) patients was right lower quadrant pain, whereas one (11%) patient presented to the emergency surgery outpatients clinic with generalised abdominal pain and weight loss. There was no abnormality in biochemistry or complete blood count of the patients except leucocytyosis in five (55%) patients. In preoperative ultrasonographic examination of the patients, appendiceal cystic mass (mucocele) with variable internal echogenicity were diagnosed in four (44.5%) patients. In one patient, admitted with

3 146 Hong Kong j. emerg. med. Vol. 18(3) May 2011 generalised abdominal pain and weight loss, abdominal CT examination was reported as appendiceal cystic tumoural mass containing cur vilinear mural calcification with enhancing nodules (Figure 1). Eight (89%) patients were operated emergently with the diagnosis of acute appendicitis, and one (11%) patient was operated emergently with the diagnosis of acute abdomen. During intraoperative exploration, a cystic mass in appendix was seen in six (67%) patients (Figure 2a) and was treated with appendectomy. In two (22%) patients, frozen section examination of the appendiceal cystic mass was reported as mucinous cystadenocarcinoma (Figure 2b) and then right hemicolectomy was done. In one (11%) patient, abdominal CT examination reported that the appendiceal cystic tumoural mass contained curvilinear mural calcifications with enhancing nodules and malignancy was suspected, therefore, right hemicolectomy was done. No synchronous ovarian or colorectal tumour was detected. In histopathologic examination, simple mucocele was diagnosed in two (22%) patients, mucinous cystadenoma was diagnosed in four (45%) patients, and mucinous cystadenocarcinoma was diagnosed in three (33%) patients. histopathologic examination revealed simple mucocele in two patients and mucinous cystadenoma in other two patients. In three (33%) patients diagnosed as mucinous cystadenocarcinoma, which was treated with right hemicolectomy, no lymph node metastasis (0/22, 0/27, 0/34) or adjacent organ invasion was seen. No postoperative morbidity or mortality occurred. Average postoperative length of hospital stay was 3.4 (2-7) days. Because there was no lymph node metastasis or adjacent organ invasion in mucinous cystadenocarcinoma cases, medical oncology did not recommend adjuvant chemotherapy. At postoperative follow up, physical examination, colonoscopy, abdominal computed tomography, carcino-embryonic antigen (CEA) and other laboratory tests were done twice a year for the first two years and yearly thereafter. Average follow up period was 32 (9-60) months. Tumours were not detected in any case subsequently. (a) In the four patients with preoperative ultrasonographic diagnosis of appendiceal cystic masses (mucocele), (b) Figure 1. Abdominal computed tomography appereance of appendiceal cystic tumoural mass. Figure 2. Intraoperative appereance of cystic mass in appendix. (a) simple mucocele; (b) mucinous cystadenocarcinoma.

4 Yakan et al./mucocele of the appendix 147 Discussion Mucocele of the appendix is a descriptive term for an appendix distended by mucus, secondary to mucinous cystadenoma (63%), mucosal hyperplasia (25%), mucinous cystadenocarcinoma (11%) and retention cyst. 5 Mucocele can also occur due to occlusion of the lumen by endometriosis or carcinoid tumour. Mucinous cystadenomas and cystadenocarcinomas are often referred to as neoplastic mucoceles. In cystadenoma, which is the most common form, the luminal dilatation reaches up to 6 cm and is associated with appendiceal perforation in 20% of the instances. This results in mucinous spillage into the periappendicular area and peritoneal cavity. Histological examination of the mucus does not reveal any neoplastic cells and appendectomy is usually curative. 6 Mucinous cystadenocarcinomas, on the other hand, are less common than mucinous cystadenomas and may present with spontaneous rupture in 6% of cases. Macroscopically, it produces mucin-filled cystic dilatation of the appendix indistinguishable from cystadenomas. However, neoplastic cells may penetrate through the appendiceal wall and spread beyond the appendix in the form of peritoneal implants. In its fully developed state, the peritoneal cavity becomes distended with adhesive, semi-solid mucin in which neoplastic adenocarcinomatous cells can be found; this condition is termed as pseudomyxoma peritonei. The intraperitoneal spread of this mucin-secreting cancer is identical to that of intra-peritoneal ovarian mucinous cystadenocarcinomas. 5,6 The clinical presentation of a mucocele is varied and usually nonspecific. Only 50% of the patients are symptomatic and in the rest it is an incidental finding at the time of surgery. 1 In the patients who are symptomatic, abdominal pain is the most common symptom followed by abdominal mass, weight loss, nausea and vomiting in decreasing order of frequency. 7 Rupture of a neoplastic appendiceal mucocele may present as appendicitis. 8 Cases of bleeding, intussusception, and local invasion into surrounding structures have been reported. 9 Consistent with the literature, abdominal pain was the most common symptom in our series. Pseudomyxoma peritonei is associated with even more nonspecific symptoms. The most frequent presentation is gradually increasing abdominal circumference. Men may present with new onset hernia, while women can develop an ovarian mass. 10 An association between appendiceal mucocele and synchronous colon neoplasms has been previously noted. 11 Appendiceal mucocele is associated with colon adenocarcinomas in 19.5%-21.4% of the cases. 2,11 In our series, no synchronous ovarian or colorectal tumour was detected during intraoperative exploration. Preoperative diagnosis is difficult, due to the nonspecific nature of the disease. The lesion may be identified by radiologic, sonographic, or endoscopic means. Elevated CEA levels have been described in neoplastic mucoceles. 12 More recently, however, modern, non-invasive imaging modalities, especially ultrasound and CT, have been shown to be extremely useful in the preoperative diagnosis of appendix mucocele, as well as demonstrating the presence of pseudomyxoma peritonei which may develop as a complication of rupture of the mucocele. In plain abdominal radiography, an appendix mucocoele may be evident as a soft tissue mass in the right lower quadrant, with mass effect on the adjacent loops of bowel or the bladder. Ultrasonography usually shows a cystic, encapsulated lesion, firmly attached to the caecum. Internal variable echogenicity is related to the density of mucus. In some patients, multiple echogenic layers along the dilated appendix produce the appearance of "onion skin-like" circles and are pathognomonic for mucocele. 2 CT features include a hypoattenuated, wellencapsulated, right lower quadrant mass with smooth margins. There may be mass effect with displacement of the adjacent bowel loops, but no significant periappen diceal inflammato r y chang es or ab scess formation, features which help to differentiate it from acute appendicitis. CT will also readily demonstrate the presence of wall calcification. 2,13 In our study,

5 148 Hong Kong j. emerg. med. Vol. 18(3) May 2011 correct preoperative diagnosis rate was 55%, one (11%) of which was by abdominal CT and four (44%) of which were by ultrasonography. Colonoscopy may show a pathognomic image, the 'volcano sign', the appendiceal orifice seen in the centre of a firm mound covered by normal mucosa or lipoma-like submucosal mass. 14 Despite the improvements in imaging tests, a correct preoperative diagnosis was achieved in only 30% of the cases in the literature. 15 Detection of mucocele in the preoperative period is important because it may change the surgical approach and prevents the need for additional operation. If the preoperative diagnosis is positive, further examination for concomitant tumours is necessary, especially for elderly patients. Treatment is surgical, but a laparoscopic approach is not advised because of the risk of rupture. 16 The type of surgical treatment is related to the dimensions and histology of the mucocele. Appendectomy is used for simple mucocele or for cystoadenoma when the appendiceal base is intact. Even though the appendiceal base is intact, in suspected cases frozen section examination should be done to differentiate between cystadenoma and cystadenocarcinoma. Caecum resection is performed for cystoadenoma with a large base, and a right hemicolectomy is recommended for cystadenocarcinoma. An accurate exploration of the abdomen during laparotomy is advised, because of the association between the appendiceal mucocele and other tumours, particularly carcinoma of the colon (19-21%). 2,11 Generalised pseudomyxoma peritonei is treated by aggressive surgical debulking of all apparent mucinous tissue. Simple mucocele, mucosal hyperplasia, and mucinous cystadenoma after appendectomy usually has an excellent prognosis with 5-year survival rates of %, but recurrences as pseudomyxoma peritonei and metachronic colonic neoplasms causing mortality can be seen 1,17 Cystadenocarcinoma without peritoneal or adjacent organ involvement also show a good outcome after surgical resection, but when it progresses to pseudomyxoma peritonei, 5-year survival is 25%, with most deaths attributed to intestinal obstruction or renal failure. 18 Bec ause of the high asso ciat ion of mucin ous cystadenoma with colon and ovarian malignancies (19-21%), 2,11 follow-up CT, US and colonoscopy examinations should be performed during the postoperative period. Our average follow up period was 32 (9-60) months. Because of this reason any postoperative malignancy was not detected in our patients but long term follow up is required to assess the final outcome. Our study was retrospective and including few number of patients. In literature, mucocele is mostly seen at patients over 50 years of age and half of them are symptomatic. In our series, average age was consistant with literature but 90% of the patients were admitted to emergency service with the complaint of right lower abdominal pain. When we consider the results of our study and literature together, emergency physicians should consider appendiceal mucocele as the differential diagnosis patients presenting with right lower quadrant pain and perform necessary additional diagnostic work-up without causing any delay. 15 Correct preoperative diagnosis of appendiceal mucoceles is important because any delay of preoperative diagnosis can cause perforation of mucocele and peritoneal dissemination of mucoid material i.e. pseudomyxoma peritonei. Accurate preoperative diagnosis allows surgeon to make the correct surgical decision. In summary, mucocele of the appendix is a rare disease and may cause acute abdominal conditions. Actual diagnosis is usually made intraoperatively or during histopathologic examination of the excised specimen. To improve the prognosis of the patient, differentiation between appendiceal mucocele and acute appendicitis is important in emergency department. Also for the surgeons, a correct preoperative diagnosis allows the planning of correct incision and extent of surgery. When a cystic mass in appendix is seen during operation, appendiceal mucocele should be kept in mind to avoid iatrogenic perforation causing pseudomyxoma peritonei and possible concomitant malignancies should be searched for.

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