Retrocecal mucocele of the appendix: Case report and review of literature – Ngo Tuan Minh

Journal of military pharmaco-medicine n o 9-2018 194 RETROCECAL MUCOCELE OF THE APPENDIX: CASE REPORT AND REVIEW OF LITERATURE Ngo Tuan Minh1; Nguyen Thi Ha1; Le Vu Duy1 Phung Anh Tuan1; Tran Quang Vinh2; Ho Van Thanh3 SUMMARY Appendiceal mucocele was described for the first time by Rokitansky in 1842 [9]. Its incidence was 0.2 - 0.4% of all apendectomies performed, as it is observed predominantly in women with the ratio of 4/1 versus men and most frequently at the age of 50. We reported a 78-year-old woman, who was admitted to the hospital because of mild pain in the right lower quadrant. Appendiceal mucocele with a retrocecal location, which is a rare position, was determined intraoperatively. The formation has been dissected and appendectomy was performed without mucocele integrity being compromised. The permanent histological specimen revealed mucinous cystadenoma with clear resection lines, without any data on the appendiceal base being affected. The patient was discharged on the third day after surgery without any complications, and further follow-up was scheduled in 6 months. * Keywords: Retrocecal mucocele of appendix. INTRODUCTION Appendiceal mucocele (AM) is a rare entity that can present with a variety of clinical symptoms or occur as an incidental surgical finding. The incidence is 0.2 - 0.4% of all appendectomied specimens [6]. AM is a progressive dilatation of the appendix from the intraluminal accumulation of the mucoid substance [4, 6]. It may be a benign or malignant process. There are four histological types, which lead to individualized surgical treatment and course in each case [6]. Preoperative diagnosis that distinguishes AM from acute appendicitis (AA) is essential for the best choice of surgical approach (open vs. laparoscopy) to prevent peritoneal dissemination and perform the appropriate surgery [6]. Herein, we reported a retrocecal AM case, which is a rare location, discuss the process of diagnosis and review the relevant literature. CASE PRESENTATION A 78-year-old woman was admitted to the hospital because of pain in the right lower quadrant of the abdomen for 2 days. When palpating the lower right quadrant of the abdomen, the patient felt mild pain, muscles were not rigid, and rebound tenderness was not noted. Body temperature was 36.8°C. Leukocytosis (8.5 x 109/L) was notable from laboratory test results. 1. 103 Military Hospital 2. 110 Military Hospital 3. Vocational School of Military Medicine Corresponding author: Ngo Tuan Minh (ngotuanminh103hospital@gmail.com) Date received: 17/08/2018 Date accepted: 21/11/2018 Journal of military pharmaco-medicine n o 9-2018 195 Ultrasonography (USG) showed a cystic mass (29.9 x 16.9 mm) with thin, calcified wall located posteriorly and originated from the ceacum. There was no finding of inflammation in the iliac fossa. Fig.1: USG showed a cystic mass with thin, calcified wall. Computed tomography (CT) revealed a well-circumscribed, low-attenuation, tubular, curvilinear and mural calcified mass contiguous with the base of the caecum. Preoperative diagnosis was retrocecal AM. Fig.2: CT demonstrated a cystic mass in the retrocecal position. The patient underwent total appendectomy and the appendiceal mucocele with retrocecal location was determined intraoperatively. Histopathological diagnosis was benign mucinous cystadenoma. Postoperative course was unremarkable and she was discharged home on the 3rd postoperative day. Journal of military pharmaco-medicine n o 9-2018 196 DISCUSSION Mucocele of the appendix was first described by Rokitansky [9]. This disease is characterized by dilatation of a lumen as a result of an accumulation of a large amount of mucus. The appendix is lined by epithelium containing more goblet cells than the colon. As a result, most appendiceal epithelial tumors are mucinous and start as mucoceles [10]. It falls under the category of rare diseases. Its incidence ranges between 0.2% and 0.7% of all excised appendixes [6]. This condition can have benign as well as malignant processes. According to modern classification, there are 4 histologic types: Retention cyst, mucosal hyperplasia, mucinous cystadenoma, and mucinous cystadenocarcinoma [3]. The clinical flow of the disease does not have a specific picture. It often flows asymptomatically. In about 50% of cases it is discovered accidentally during radiologic and endoscopic examinations or at surgery. A patient’s clinical symptoms may include pain in the right lower quadrant of the abdomen, palpable abdominal mass, nausea, vomiting, weight loss, gastrointestinal bleeding, and signs of intussusception of the intestines [5, 10]. Preoperative diagnosis of appendicular mucocele is very important for the selection of an adequate surgical method to prevent peritoneal dissemination, to prevent intraoperative and postoperative complications, and repeated surgery [10]. USG, CT, and colonoscopy are used for diagnostics. Radiographically, a mucocele is seen as a soft tissue mass, possibly with peripheral curvilinear calcification. The typical image, called ‘onion skin’, is an important sonographic marker of AM [1]. Visualisation of appendix and its diameter exceeding 15 mm is considered as specific appendiceal mucocele index with sensitivity of 83% and specificity of 92% [5]. Discontinuity of the appendiceal wall with leakage of the internal contents into surrounding tissues indicates rupture of the mucinous tumor [11]. In cases of developed pseudomyxoma peritonei (PMP), typical ultrasound findings are non-mobile, sonogenic ascites with multiple semi solid masses and scalloping of the hepatic and splenic margins [12]. In case of CT, it is important to assess formation interrelation with surrounding organs, which may make diagnostication easier. CT is considered to be the most informative imaging method, although accurate diagnostication is often not possible. In most of the cases, a well- capsulated cystic formation with calcificates in the wall is visualised, which is considered a specific index, as well [7]. Another important CT indication is the presence of appendiceal lumen exceeding 1.3 cm [2]. When the mucinous tumor is ruptured and pseudomyxoma peritonei is developed, the most common findings on a CT-scan are a large volume of mucinous ascites with the density of fat that displace the small bowel and the normal mesenteric fat [12]. Other characteristic findings are omental thickening, multiseptate lesions, scalloping of organs, and curvilinear calcifications [12]. At first, the patient was performed USG. Ultrasonography showed a cystic mass (29.9 x 16.9 mm) with thin, calcified Journal of military pharmaco-medicine n o 9-2018 197 walls located posteriorly and originated from the ceacum. There was no finding of inflamation in the iliac fossa, therefore it might not have been appendicitis. So, we could not make an appropriate diagnosis, and CT was requested. CT revealed a well-circumscribed, low-attenuation, tubular, curvilinear and mural calcified mass contiguous with the base of the ceacum. Preoperative diagnosis was retrocecal AM. Surgery is the only treatment with curative potential. Surgical treatment depends on the dimensions and histology of the mucinous neoplasm, as well as the clinical presentation [11]. During the operation we must be cautious while handling the mucocele to avoid rupture and dispersion of mucus or epithelial cells into the peritoneal cavity as this is associated with a poorer prognosis [11]. Conventional surgery is preferred rather than laparoscopic approaches for the treatment [5]. Laparoscopic approach has an increased risk of rupture and subsequent pseudomyxoma peritonei formation. CONCLUSION Appendiceal mucocele is a rare disease and has a clinical picture that resembles acute appendicitis. A correct diagnosis before surgery is very important for the selection of surgical technique to avoid severe intraoperative and postoperative complications. USG, particularly CT, should be used extensively for this purpose. In our opinion, every patient more than 50 years old who arrives at the emergency department with clinical symptoms of acute appendicitis must undergo CT and open surgery should be favored against laparoscopic surgery REFERENCES 1. Caspi B et al. The onion skin sign: A specific sonographic marker of appendiceal mucocele. J Ultrasound Med. 2004, 23 (1), pp.117-21, quiz 122-123. 2. Demetrashvili Z. 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