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 Table of Contents  
Year : 2020  |  Volume : 17  |  Issue : 3  |  Page : 57-60

Neoplasms of the appendix: An experience of a tertiary hospital in Southwestern Nigeria

1 Department of Pathology, University College Hospital; Department of Pathology, College of Medicine, University of Ibadan, Ibadan, Oyo State, Nigeria
2 Department of Anatomical Pathology, Edo University, Iyamho, Edo State, Nigeria
3 Department of Pathology, University College Hospital, Ibadan, Oyo State, Nigeria

Date of Submission21-Mar-2020
Date of Acceptance18-May-2020
Date of Web Publication04-Jul-2020

Correspondence Address:
Dr. Mustapha Akanji Ajani
Department of Pathology, College of Medicine, University of Ibadan and University College Hospital, Ibadan, Oyo State
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jcls.jcls_19_20

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Background: The appendix is a vestigial tube-like organ. Its exact physiological function is unknown. Appendectomies are done usually following a clinical diagnosis of acute appendicitis. Neoplasms can arise from this organ as well. Carcinoids are the most common neoplasms arising commonly at the tips. This retrospective review of neoplasms of the appendix was aimed at identifying the incidence and describing the histological variants of neoplasms of the appendix in our environment. Materials and Methods: This study was a 10-year retrospective review of all appendectomy specimens submitted to the Department of Pathology, University College Hospital, Ibadan, Nigeria, from January 1, 2009, to December 31, 2018. Microscopy was done examining the longitudinal sections from the tip to the base of the appendix. The histological diagnosis was extracted from the records in the department and classified using the WHO classification of tumors of the appendix (2019). Patients' biodata such as age and sex were also extracted. The data were analyzed for frequency distribution using SPSS 23. Results: The incidence of neoplasms in the appendix was 0.84% of the 1071 appendectomies received in our department over the study period. Low-grade appendiceal mucinous neoplasm (LAMN) was the most common histological variant accounting for 55.5% of neoplasms, followed by metastatic carcinoma at 22.2% and carcinoids at 11.1%. There was a female preponderance of 77.8%. Conclusion: Neoplasms of the appendix are rare in our environment, and LAMN was the most common neoplasm of the appendix in our institution. There is a female preponderance among patients with appendiceal neoplasms.

Keywords: Appendix, Ibadan, neoplasms, Nigeria

How to cite this article:
Ajani MA, Omenai SA, Iyapo O. Neoplasms of the appendix: An experience of a tertiary hospital in Southwestern Nigeria. J Clin Sci 2020;17:57-60

How to cite this URL:
Ajani MA, Omenai SA, Iyapo O. Neoplasms of the appendix: An experience of a tertiary hospital in Southwestern Nigeria. J Clin Sci [serial online] 2020 [cited 2023 Jun 2];17:57-60. Available from: https://www.jcsjournal.org/text.asp?2020/17/3/57/288904

  Introduction Top

Neoplastic lesions of the appendix are relatively rare and found only in about 2% of all appendectomies.[1],[2] Appendectomies are mainly done on account of the clinical diagnosis of appendicitis. Histopathological examination of routine surgical appendix has shown few incidental neoplastic lesions and even negative appendectomies. Hence, most cases of neoplasms of the appendix are only evident after surgical intervention and histological review. The type of neoplasms and their clinical course seen in the appendix vary widely.[3] Patients commonly present with symptoms such as right lower abdominal pain, and vomiting, similar to those of acute appendicitis. There have been reports of appendiceal neoplasm presenting with significant weight loss, fatigue, abdominal mass, and intestinal volvulus.[4],[5]

The appendix gives rise to neoplasms with glandular or neuroendocrine differentiation. Epithelial tumors of the appendix range from low grade localized to the mucosal to high-grade invasive tumors.[6] Low-grade appendiceal mucinous neoplasms (LAMNs) are the most common histological type of mucin-producing epithelial neoplasms in a study by Misdrajiet al.[6] The most common neoplastic lesion of the appendix is the carcinoid tumor, which is usually located at the tip of the appendix.[1],[7],[8],[9]

LAMNs include tumors previously known as villous adenoma, cystadenoma, and mucinous tumor of uncertain malignant potential.[6],[10] LAMNs are a group of mucinous neoplasm with low-grade cytology. They can present with dissecting of mucin in the appendix wall, and in some cases, mucin or neoplastic cells can be found outside of the appendix.[11] The presence of extraappendiceal neoplastic epithelial cells is a poor prognostic marker as their 5- and 10-year survival rates are 79% and 46%, respectively.[10] Intraappendiceal LAMN or those with just extraappendiceal acellular mucin are usually cured by surgical intervention.[10],[12],[13],[14]

High-grade appendiceal mucinous neoplasms (HAMNs) are mucinous neoplasms with high-grade cytology present at least focally, but show no infiltrative growth pattern.[11] A diagnosis of HAMN should be made after carefully examining the specimen and excluding mucinous adenocarcinoma. If neoplastic cells are seen outside the appendix or localized area within the peritoneum, a diagnosis of HAMN is excluded, and the most appropriate diagnosis will be a mucinous adenocarcinoma.[11]

Mucinous adenocarcinoma of the appendix is made when there is presence of infiltrative neoplastic cells with high-grade cytology in a mucinous neoplasm.[11] Mucinous adenocarcinoma of the appendix is associated with a dysplastic mucosa; this usually supports a diagnosis of an appendiceal primary in cases that present mainly with pseudomyxoma peritonei.[7] Mucinous adenocarcinomas are clinically aggressive and frequently metastasize to the peritoneum.[11] It has poor prognosis with a 5-year survival rate of 28%.[10],[15]

Mucinous signet ring cell carcinoma is a mucinous adenocarcinoma with 50% or more of the tumor containing signet ring cells. Tumors with signet ring morphology <50% are referred to mucinous adenocarcinoma with signet ring cells.[11] Mucinous adenocarcinoma can either be Grade 2 or 3 tumors, whereas mucinous signet ring cell carcinomas are poorly differentiated and thus Grade 3 tumors.[11]

Neuroendocrine tumors are the most common type of tumors in the appendix. It can either be Grade 1, 2, or 3. Well-differentiated neuroendocrine (Grade 1) tumors (carcinoid tumor) is the most frequent neoplasm of neuroendocrine origin.[7] Carcinoid tumors are commonly found at the tip of the appendix. Carcinoid tumors have higher incidence in females and rarely metastasize to the liver.[1] Neuroendocrine tumors can be functional or nonfunctional. If functional, patients will present with the symptoms of carcinoid syndrome.[1]

The aim of this study was to describe the histopathological characteristics of neoplasms of the resected appendix.

  Materials and Methods Top

This is a 10-year retrospective review of the histopathology reports of resected vermiform appendix histopathology records of the Department of Pathology, University College Hospital, Ibadan, Nigeria, from January 1, 2009, to December 31, 2018. The requests were made after surgical intervention for the clinical diagnosis of acute appendicitis. Right hemicolectomy specimens with appendix examined were excluded from this study. Age, gender, and histological diagnosis were extracted from the records. Microscopic examination involved examining the tip of the appendix, taken longitudinally and two other circumferential samples taken from the base and mid-portion. The histological diagnosis was classified using the 5th edition of the WHO classification of tumors of the appendix (2019).[16] The descriptive analysis was done using the Statistical Package for the Social Sciences, version 23 (SPSS Inc, Chicago, Illinois, USA).

  Results Top

There were nine cases with neoplastic lesions out of the 1071 appendectomies examined, representing an incidence of 0.84% over the study period. Neoplasms were more common in females who accounted for 77.8% of the cases [Figure 1]. The modal age group was in the fourth decade [Table 1]. LAMN was the most common diagnosis [Table 2]. One of the cases affected the appendix, ovary, and the omentum, and the primary site could not be ascertained. The LAMN did not show significant differences in incidence between males and females [Table 3]. Majority (40%) of the LAMNs occurred in the fourth decade [Table 4].
Figure 1: Pie chart showing sex distribution of malignant appendiceal neoplasms

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Table 1: Age group distribution

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Table 2: Frequency and percentage distribution of the histological types of tumors of the appendix

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Table 3: Distribution of appendiceal neoplasms within gender

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Table 4: Distribution of neoplasms of the appendix in age decades

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  Discussion Top

Appendectomies are routine specimens received and evaluated by histopathology laboratories. They are usually performed for the clinical diagnosis of appendicitis. Neoplastic lesions of the appendix are relatively rare accounting for <2% of all appendectomies.[2],[8],[13] The 0.84% incidence of neoplastic appendix in this study is very similar to that of Charfi et al. who recorded an incidence of 0.7%.[8] There are some reviews from Nigeria and Africa that did not record any neoplastic lesion in their series.[17],[18],[19]

LAMN was the most common epithelial neoplasm of the appendix in this study. This differs from the usual pattern of carcinoid tumors being the most common.[1],[8] This is interesting as we recorded only one case of carcinoid in our review. Misdraji et al. who reviewed epithelial neoplasms of the appendix excluding the carcinoids demonstrated that that LAMN s were the most common.[20] Our findings are also similar to a finding in Bengaluru by Geetha et al. who reported that mucocele was the most common neoplasm, followed by carcinoids.[21] Mucocele is a gross descriptive term and not a histopathological diagnosis as it could be as a result of a hyperplastic polyp, LAMN, or even mucinous adenocarcinoma.[6],[22],[23] Misdraji et al and Carr et al. in their studies reported equal percentages of adenocarcinomas and carcinoids.[6],[24] These tumors have good prognosis when confined to the luminal mucosal without invasion.[6],[24] These tumors could rupture and spread to involve the peritoneum and such state is referred to as pseudomyxoma peritonei. LAMN typically occurs in the sixth decade with a wide age range of 20–89 years.[20] In our series, we had modal age of diagnosis to be the fourth decade and had none in the sixth decade. These disparities in histological type and modal age of presentation are likely due to the few numbers of cases seen in this study. LAMN has a varying presentation; it can be suspected during gross examination of the appendectomy specimen with mucin present in the surface or can be grossly unremarkable.[20] About 80% of LAMNs are confined to the appendiceal wall, and 42% of these can have dissection into the muscularis propria.[25],[26] In 20% of LAMNs, there is associated perforation or just presence of acellular mucin serosal deposits without a recognizable breach of the muscularis propria.[20],[26] LAMNs show frequent mutations in GNAS and KRAS genes.[27] All LAMNs are Grade 1 (well differentiated) tumors.[11] The staging of LAMN is different from how other gastrointestinal tumors are staged. A tumour confined to the appendix is carcinoma in situ or intramucosal carcinoma; Tis (LAMN), even if mucin dissects into the muscularis propria. There are no pT1 and pT2 stages. pT3 is when mucin with or without neoplastic cells is seen within the subserosa, and pT4 is when there is peritoneal deposit.[11]

In mucinous adenocarcinoma, the wall of the appendix may appear grossly thickened or encased by tumor, and microscopy commonly shows infiltration of a desmoplastic stroma.[20] Some cases of mucinous adenocarcinoma can be confined to the appendix, although there is usually marked cellular atypia and stromal invasion.[20] Peritoneal carcinomatosis when confined to the abdominal cavity is effectively treated with cytoreductive surgery and hyperthermic intraperitoneal chemotherapy.[28] Early intervention using these treatment modalities improves outcome with a median survival of 27 months compared to 15 months for those who had just chemotherapy.[28]

  Conclusion Top

Neoplasms of the appendix are rare in our environment and are more common in females. LAMN is the most common neoplasm of the appendix in our institution. The result of this study may not be truly representative because of the low number of the neoplasms identified. It is very important to examine all appendectomies done for supposed appendicitis. If a neoplasm is diagnosed and properly staged, it will allow for early referral for appropriate and adequate treatment.

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Conflicts of interest

There are no conflicts of interest.

  References Top

O'Donnell ME, Badger SA, Beattie GC, Carson J, Garstin WI. Malignant neoplasms of the appendix. Int J Colorectal Dis 2007;22:1239-48.  Back to cited text no. 1
Marudanayagam R, Williams GT, Rees BI. Review of the pathological results of 2660 appendicectomy specimens. J Gastroenterol 2006;41:745-9.  Back to cited text no. 2
Sugarbaker PH. The natural history, gross pathology, and histopathology of appendiceal epithelial neoplasms. Eur J Surg Oncol 2006;32:644-7.  Back to cited text no. 3
Costa V, Demuro JP. Low-grade appendiceal neoplasm presenting as a volvulus of the cecum. Gastroenterol Rep (Oxf) 2013;1:207-10.  Back to cited text no. 4
Padmanaban V, Morano WF, Gleeson E, Aggarwal A, Mapow BL, Stein DE, et al. Incidentally discovered low-grade appendiceal mucinous neoplasm: A precursor to pseudomyxoma peritonei. Clin Case Rep 2016;4:1112-6.  Back to cited text no. 5
Misdraji J, Young RH. Primary epithelial neoplasms and other epithelial lesions of the appendix (excluding carcinoid tumors). Semin Diagn Pathol 2004;21:120-33.  Back to cited text no. 6
Tang LH. Epithelial neoplasms of the appendix. Arch Pathol Lab Med 2010;134:1612-20.  Back to cited text no. 7
Charfi S, Sellami A, Affes A, Yaïch K, Mzali R, Boudawara TS. Histopathological findings in appendectomy specimens: A study of 24,697 cases. Int J Colorectal Dis 2014;29:1009-12.  Back to cited text no. 8
Thaker B, Gupta D, Singh K. Histopathology of appendicectomy specimen: A 5 year hospital based study. JMSCR 2017;05:23773-6.  Back to cited text no. 9
Pai RK, Beck AH, Norton JA, Longacre TA. Appendiceal mucinous neoplasms: Clincopathologic study of 116 cases with analysis of factors predicting Recurrence. Am J Surg Pathol 2009;33:1425-39.  Back to cited text no. 10
Valasek MA, Pai RK. An update on the diagnosis, grading, and staging of appendiceal mucinous neoplasms. Adv Anat Pathol 2018;25:38-60.  Back to cited text no. 11
Guaglio M, Sinukumar S, Kusamura S, Millione M, Pietrantonio F, Battaglia L, et al. Clinical surveillance after macroscopically complete surgery for low-grade appendiceal mucinous neoplasms (LAMN) with or without limited peritoneal spread: Long-term results in a prospective series. Ann Surg Oncol 2018;25:878-84.  Back to cited text no. 12
Fournier K, Rafeeq S, Taggart M, Kanaby P, Ning J, Chen HC, et al. Low-grade appendiceal mucinous neoplasm of uncertain malignant potential (LAMN-UMP): Prognostic factors and implications for treatment and follow-up. Ann Surg Oncol 2017;24:187-93.  Back to cited text no. 13
Arnason T, Kamionek M, Yang M, Yantiss RK, Misdraji J. Significance of proximal margin involvement in low-grade appendiceal mucinous neoplasms. Arch Pathol Lab Med 2015;139:518-21.  Back to cited text no. 14
Huang Y, Alzahrani NA, Chua TC, Morris DL. Histological subtype remains a significant prognostic factor for survival outcomes in patients with appendiceal mucinous neoplasm with peritoneal dissemination. Dis Colon Rectum 2017;60:360-7.  Back to cited text no. 15
Misdraji J, Carr NJ, Pai RK. Tumours of the appendix. In: Nagtegeal ID, Klimstra DS, Washington MK, editors. WHO Classification of Tumours of the Digestive System. 5th ed. Lyon: World Health Organisation; 2019. p. 135-52.  Back to cited text no. 16
Omotoso J, Nnoli MA, Ekanem I. Histopathological analysis of appendectomy specimens in Calabar, South – Southern Nigeria. IOSR JVSP 2013;2:42-6.  Back to cited text no. 17
Udoye EP, Koroye OF. Appendicectomy specimens in Bayelsa State, Nigeria. An 8 year clinicopathological analysis of 539 cases. IOSR JDMS 2018;17:1-6.  Back to cited text no. 18
Mshiyeni P, Hospital M, Africa S. A clinicopathological review of 324 appendices removed for acute appendicitis in Durban, South Africa: A retrospective analysis. Ann R Coll Surg Engl 2009;91:688-92.  Back to cited text no. 19
Misdraji J, Yantiss RK, Graeme-Cook FM, Balis UJ, Young RH. Appendiceal mucinous neoplasms: A clinicopathologic analysis of 107 cases. Am J Surg Pathol 2003;27:1089-103.  Back to cited text no. 20
Geetha RL, Anitha MR, Vijayanath V, Kavitha GU. Spectrum of histopathological lesions in appendix in a tertiary care Centre at Bangalore. J Med Res Pract 2012;1:2011-2.  Back to cited text no. 21
Pai RK, Longacre TA. Appendiceal mucinous tumors and pseudomyxoma peritonei: Histologic features, diagnostic problems, and proposed classification. Adv Anat Pathol 2005;12:291-311.  Back to cited text no. 22
Tirumani SH, Fraser-Hill M, Auer R, Shabana W, Walsh C, Lee F, et al. Mucinous neoplasms of the appendix: A current comprehensive clinicopathologic and imaging review. Cancer Imaging 2013;13:14-25.  Back to cited text no. 23
Carr NJ, McCarthy WF, Sobin LH. Epithelial noncarcinoid tumors and tumor-like lesions of the appendix. A clinicopathologic study of 184 patients with a multivariate analysis of prognostic factors. Cancer 1995;75:757-68.  Back to cited text no. 24
Lamps LW, Gray GF Jr., Dilday BR, Washington MK. The coexistence of low-grade mucinous neoplasms of the appendix and appendiceal diverticula: A possible role in the pathogenesis of pseudomyxoma peritonei. Mod Pathol 2000;13:495-501.  Back to cited text no. 25
Qizilbash AH. Mucoceles of the appendix. Their relationship to hyperplastic polyps, mucinous cystadenomas, and cystadenocarcinomas. Arch Pathol 1975;99:548-55.  Back to cited text no. 26
Nishikawa G, Sekine S, Ogawa R, Matsubara A, Mori T, Taniguchi H, et al. Frequent GNAS mutations in low-grade appendiceal mucinous neoplasms. Br J Cancer 2013;108:951-8.  Back to cited text no. 27
Shankar S, Ledakis P, El Halabi H, Gushchin V, Sardi A. Neoplasms of the appendix: Current treatment guidelines. Hematol Oncol Clin North Am 2012;26:1261-90.  Back to cited text no. 28


  [Figure 1]

  [Table 1], [Table 2], [Table 3], [Table 4]

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