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Pre-operative identification and surgical management of the appendiceal mucocele: a case report.

Introduction

First described by Rokitansky in 1842, an appendiceal mucocele (AM) occurs in 0.2-0.3%, of appendectomy specimens and can be a result of four entities: mucosal hyperplasia, retention cysts, mucinous cystadenomas, or mucinous cystadenocarcinomas. (1) Surgical resection of all AMs is generally recommended to prevent neoplastic transformation and mucocele rupture. Moreover, 20% of AMs have a concomitant colorectal adenocarcinoma, so colonoscopy of AM patients is recommended. Spilled mucoid material may contain neoplastic cells, causing pseudomyxoma peritonei (2) and resulting in a 50% 5-year survival. In order to avoid spillage, the traditional approach has been to perform a right hemicolectomy. (3) AMs are of interest because of their relative infrequency as well as the questions surrounding their surgical management. We present an AM case and consider three questions particularly germane to this condition: First, in what patient should the physician suspect an AM? Second, is a right hemicolectomy mandatory for all AMs? Lastly, is a laparoscopic approach safe?

Case Report

A 60-year-old male first presented to the ED with new onset left lower quadrant pain radiating into his right testicle. A CT scan was suggestive of sigmoid diverticulitis, so the patient was given ciprofloxacin and metronidazole and discharged. Seven days later, the patient returned to the ED with nausea and periumbilical pain (8/10) that radiated to the right lower quadrant. It was described as sharp and constant, and had been worsening for one day. On physical exam, tenderness to palpation was found in the right lower quadrant, and a straight leg raise test was positive. The patient was afebrile with a white blood cell count of 7100 cells/microliter. There was no family history of cancer and a colonoscopy was negative ten years prior. A repeat CT scan (Figure 1) on this return to the ED was remarkable for sigmoid diverticula as well as an enlarged appendix. Comparison of the two CTs showed that the appendix had grown from 1.8 cm diameter to 3 cm.

The patient was taken to the OR that day for a diagnostic laparoscopy, which revealed a large, dilated appendix that lacked the usual inflammatory findings. There was no evidence of leak, perforation, or pseudomyxoma peritonei. Clinically appearing like an appendiceal mucocele, the procedure was converted to an open appendectomy. After careful dissection, the appendix was mobilized and examined.

The mucocele appeared to stop directly at the base of the appendix; accordingly 1 cm of cecum was excised along with the appendix to assure a clean surgical margin. Postoperative course was unremarkable. Pathology showed a 4.5 x 2.5 x 2.5 cm appendix with a wall thickness of 0.3 cm. The lumen had a diameter of 2.0 cm and was filled with clear mucus. The lesion was diagnosed as a mucinous cystadenoma with clear surgical margins, without penetration of the appendiceal wall by mucin or by neoplastic epithelium. Patient presented to follow-up where colonoscopy was planned for the near future.

Discussion

Demographics and Presentation:

The average AM patient is around 40-60 years old. (2, 4-6) We have reviewed the presenting symptoms associated with AM (Table 1). The usual presentation is of right lower quadrant abdominal pain although this is not a reliable sign; many are asymptomatic. One older European series even reported that patients may present with signs of sepsis, though to our knowledge this finding was not documented in more recent publications.Overall, presenting symptoms varied widely among case series. Symptomatic AMs are commonly misdiagnosed as acute appendicitis (AA). (7) Diagnosis is rarely preoperative, occurring in only 29% of cases presenting to one university hospital, and is frequently made incidentally during colonoscopy or surgery. (8)

Since AMs often present like AA, CT scan and ultrasound of the abdomen are invaluable for preoperative identification of the AM. On ultrasound AMs are characterized by a "cystic mass with variable internal echogenicity, layered wall and calcification in the wall". (9) CT scans show a well encapsulated, cystic mass (9), and may have a 95% sensitivity for such neoplasms. (10) Leukocytosis is present in 40% of AM cases, and is associated with a presentation like that of acute appendicitis. (11) Carcinoembryonic antigen (CEA) may also be elevated in neoplastic AMs. (11,12) With any of the above findings, the clinician should have a high index of suspicion for AM because the surgical management of an AM may differ from that of AA. (9)

Extent of Resection:

Following a 1963 observational series showing a survival benefit for right hemicolectomy over appendicectomy in adenocarcinoma patients (3) (N=43), a right hemicolectomy became standard for appendiceal epithelial malignancies. In 2004, a prospective study of mucinous appendiceal tumors with peritoneal seeding (N=501) challenged this view, as it did not observe a benefit for right hemicolectomy beyond that of an appendectomy. (13) Gonzalez-Moreno and colleagues consequently recommended right hemicolectomy only for patients with appendiceal cancer and peritoneal seeding if:

1. Right hemicolectomy was necessary to resect the primary tumor

2. Histopathology revealed involvement of appendiceal or ileocolic lymph nodes

3. A non-mucinous appendiceal tumor was identified.

Many now believe appendectomy is curative of non-neoplastic AMs and cystadenomas that fail to meet those criteria, while right hemicolectomy is still recommended in cases of positive appendiceal/ileocolic lymph nodes, synchronous tumors (14) mucinous cystadenomacarcinomas (2) or cystadenomas involving the appendiceal base. (14-16)

[FIGURE 1 OMITTED]

Given that AMs are often discovered intraoperatively, a standardized approach to the unexpected AM is desirable. Gonzalez-Moreno and colleagues advocate removing the mesoappendix en bloc with the appendix, and if gross pathology suggests malignancy, then performing frozen-section would be warranted. A radical right hemicolectomy would be indicated for nodal metastases on the frozen section. (13) One caveat of this strategy is that intraoperative histologic examinations of AMs relies on evidence of stromal invasion and nuclear atypia of the appendix epithelium, and distinguishing benign from malignant appendiceal neoplasms can sometimes be challenging. (2, 15-17)

Laparoscopic vs. Open Appendectomy

Laparoscopic appendectomies are becoming the preferred approach to acute appendicitis in part because of decreases in wound infection, postoperative pain, hospital stays and overall recovery time. In cases where AM is present, the appendix becomes prone to rupture unless handled with care, risking pseudomyxoma peritonei. (2) Many argue that laparoscopic removal increases this risk, (2, 14, 16) though to our knowledge large case controlled studies testing this assumption have not been conducted. Some also believe laparoscopic resection risks seeding port sites with neoplastic cells (2) and that open procedures allow better inspection and palpation for additional tumors. (2, 14) Missed malignancies during a laparoscopic appendectomy that would likely have been palpated in an open procedure (13, 18) have led some to argue that laparoscopic appendectomy should be contraindicated in AMs. (15)

Nonetheless, successful laparoscopic AM resections without spillage have been described. (19) A review of excised appendiceal neoplasms found invaded surgical margins in 20% of laparoscopy cases and 6% of conventional appendectomy cases, however, 5 year survival rates between groups were similar (N=43). (20) Bucher and coworkers concluded that the conventional technique should be preferred until the safety of the laparoscopic approach to the AM has been better studied, and we concur with this assessment.

Conclusion

Since AMs present like AA, ultrasound and CT scans may facilitate preoperative identification, helping avoid intraoperative spillage. Appendectomy with negative margins is usually curative; guidelines have been proposed to determine the necessity for a right hemicolectomy. Currently, it is unclear whether laparoscopic AM resection has comparable safety to open appendectomy.

References

(1.) Smeenk RM, van Velthuysen ML, Verwaal VJ, Zoetmulder FA. Appendiceal neoplasms and pseudomyxoma peritonei: a population based study. EJSO. Feb 2008;34(2):196-201.

(2.) Papaziogas B, Koutelidakis I, Tsiaousis P, et al. Appendiceal mucocele. a retrospective analysis of 19 cases. J Gastrointest Canc. 2007;38(2-4):141-147.

(3.) Hesketh KT. The management of primary adenocarcinoma of the vermiform appendix. Gut. Jun 1963;4:158-168.

(4.) Aho AJ, Heinonen R, Lauren P. Benign and malignant mucocele of the appendix. Histological types and prognosis. Acta chirurgica Scandinavica. 1973;139(4):392-400.

(5.) Stocchi L, Wolff BG, Larson DR, Harrington JR. Surgical treatment of appendiceal mucocele. JAMA Surgery. Jun 2003;138(6):585-589; discussion 589-590.

(6.) Misdraji J, Yantiss RK, Graeme-Cook FM, Balis UJ, Young RH. Appendiceal mucinous neoplasms: a clinicopathologic analysis of 107 cases. Am. J. Surg. Pathol. Aug 2003;27(8):1089-1103.

(7.) Roberge RJ, Park AJ. Mucocele of the appendix: an important clinical rarity. JEM. Apr 2006;30(3):303-306.

(8.) Zanati SA, Martin JA, Baker JP, Streutker CJ, Marcon NE. Colonoscopic diagnosis of mucocele of the appendix. Gastrointest. Endosc. Sep 2005;62(3):452-456.

(9.) Kim SH, Lim HK, Lee WJ, Lim JH, Byun JY. Mucocele of the appendix: ultrasonographic and CT findings. Abdom. Imaging. May-Jun 1998;23(3):292-296.

(10.) Pickhardt PJ, Levy AD, Rohrmann CA, Jr., Kende AI. Primary neoplasms of the appendix manifesting as acute appendicitis: CT findings with pathologic comparison. Radiology. Sep 2002;224(3):775-781.

(11.) Landen S, Bertrand C, Maddern GJ, et al. Appendiceal mucoceles and pseudomyxoma peritonei. Surg, Gynecol & Obstet. Nov 1992;175(5):401-404.

(12.) Farah-Klibi F, Kourda-Boujemaa J, Bouaskar I, Dziri C, Rachida Z, Jilani-Baltagi SB. Cystadenocarcinoma of the appendix: an incidental perioperatory finding in a patient with adenocarcinoma of the ascending and sigmoid colon: case report and review of literature. Pathologica. Dec 2009;101(6):255-260.

(13.) Gonzalez-Moreno S, Sugarbaker PH. Right hemicolectomy does not confer a survival advantage in patients with mucinous carcinoma of the appendix and peritoneal seeding. Br J Surg. Mar 2004;91(3):304-311.

(14.) Dhage-Ivatury S, Sugarbaker PH. Update on the surgical approach to mucocele of the appendix. J Am Coll Surg. Apr 2006;202(4):680-684.

(15.) Zagrodnik D, Rose M. Mucinous cystadenoma of the appendix: diagnosis, surgical management, and follow-up. Curr Surg. May-Jun 2003;60(3):341-343.

(16.) Rampone B, Roviello F, Marrelli D, Pinto E. Giant appendiceal mucocele: report of a case and brief review. World J. Gastroenterol. Aug 14 2005;11(30):4761-4763.

(17.) Carr NJ, Sobin LH. Unusual tumors of the appendix and pseudomyxoma peritonei. Semin Diagn Pathol. Nov 1996;13(4):314-325.

(18.) Shayani V. Mucinous cystadenoma of the cecum missed at laparoscopic appendectomy. Pitfalls in laparoscopy. Surg Endosc. Dec 1999;13(12):1236-1237.

(19.) Rangarajan M, Palanivelu C, Kavalakat AJ, Parthasarathi R. Laparoscopic appendectomy for mucocele of the appendix: Report of 8 cases. Indian J. Gastroenterol. Sep-Oct 2006;25(5):256-257.

(20.) Bucher P, Mathe Z, Demirag A, Morel P. Appendix tumors in the era of laparoscopic appendectomy. Surg Endosc. Jul 2004;18(7):1063-1066.

Kevin Lynch, BS

MD Candidate Class of 2017, WVU School of

Medicine

Sung Cho, MD, FACS

Department of Surgery, WVU

Robert Andres, MD, PhD

Department of Surgery, WVU

Jennifer Knight, MD, FACS

Department of Surgery, WVU

Jorge Con, MD, FACS

Department of Surgery, WVU

Corresponding Author: Jorge Con, MD, Assistant

Professor, Dept. of Surgery, PO Box 9238, One

Medical Center Dr., Morgantown, WV 26506-9238.

Email:jocon@hsc.wvu.edu
Table 1: Presenting Symptoms of the Appendiceal Mucocele

Ref. (Series Size)   None   Abdominal   Palpable   Weight
                              Pain        Mass      Loss

Stocchi 2003 (135)   51%       27%        16%       10%
Aho 1973 (60)        23%       64%        18%        NR
Misdraji 2003 (88)    NR       10%        32%        NR
Landen 1992 (8)       NR      100%        38%        NR

Ref. (Series Size)    Nausea    Tenderness   Sepsis   Urinary
                     Vomiting     in RLQ              Symptoms

Stocchi 2003 (135)      9%          NR         NR        NR
Aho 1973 (60)           NR         38%         NR        NR
Misdraji 2003 (88)      NR          NR         NR        NR
Landen 1992 (8)         NR          NR        63%       50%

* NR = not reported
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Title Annotation:Case Report
Author:Lynch, Kevin; Cho, Sung; Andres, Robert; Knight, Jennifer; Con, Jorge
Publication:West Virginia Medical Journal
Article Type:Clinical report
Date:Jul 1, 2016
Words:1909
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