Histomorphological study of appendectomy specimens in a tertiary care hospital – A retrospective study

Priyatharsini Pari 1, Bharathi Udhayakumar 2, Priyadharisini Jayakumar 3

Affiliation:
1. Assistant Professor, Department of Pathology
Vinayaka Mission Medical College and Hospital, Vinayaka Mission’s Research Foundation, Deemed to be University, Karaikal, Pondicherry, India
2. Assistant Professor, Department of Pathology
Sri Lakshmi Narayana Institute of Medical Sciences, Puducherry, India
3. Associate Professor, Department of Pathology
Sri Lakshmi Narayana Institute of Medical Sciences, Puducherry, India

Corresponding author:
Dr. Priyatharsini Pari, MD (Pathology)
B-11, Sathyamoorthy Salai, Block -3, Neyveli – 607801
Email id: [email protected]

DOI:
DOAJ: 85b9686661ae44a0a864bf30041529c4

Copyright: This is an open-access article under the terms of the Creative Commons Attribution License which permits use, distribution, and reproduction in any medium, provided the original work is properly cited.

©2022 The Authors. Caribbean Medical Journal published by Trinidad & Tobago Medical Association.

Abstract
Objectives
The vermiform appendix is a vestigial organ that is present at the posteromedial wall of the caecum. Acute appendicitis is one of the common causes of acute abdominal pain. This condition is more common in young adults age group. Histopathological examination of the appendix helps in confirmation of appendicitis as well as can reveal many incidental findings. Hence this study was undertaken to see the spectrum of histopathological findings in the appendectomy specimens.

Methods
A retrospective study was conducted in Sri Lakshmi Narayana Institute of Medical Sciences, Puducherry, India to study the histopathological spectra of the appendectomy specimens over a period of two years from Jan 2019 to Jan 2021. Patients’ clinical findings, gross and microscopic findings were recorded.

Results
A total case of 180 appendectomy specimens was studied. Among the study population, the male to female ratio is 1.25:1. In our study, the peak incidence was found between the age group of 21-40 years. The patient most commonly presented with the symptom of right iliac fossa pain. The most common cause was acute appendicitis followed by acute recurrent appendicitis. We also encountered 3 cases of appendicitis with Enterobius vermicularis which was an incidental finding. A single case of fibrous obliteration of the appendix and tuberculosis of the appendix was reported.

Conclusion
Histopathological examination of appendectomy specimens is mandatory since they help not only to confirm the diagnosis of acute and acute recurrent appendicitis, but also play an important role in identifying incidental findings which may mandate further treatment.

Keywords: Appendix, Microscopy, Histopathology, Incidental findings

Introduction

Appendix vermiformis is a true diverticulum that arises from the posteromedial border of the cecum and lies close to the ileocecal valve. The base of the appendix is most commonly located at the tip of the cecum, which is an important landmark for the surgeon’s performing appendectomy. The Latin term vermiform stands for “worm-like”. ¹ Acute appendicitis is one of the most common causes of emergency surgeries. Sometimes the diagnosis of acute appendicitis challenges the skills of the physician. ²  Hence Histopathology remains the gold standard for the confirmation of acute appendicitis. Not only for confirmation, but histopathology also plays an important role in the incidental findings of tumours or parasites.³ This study aims to evaluate the incidence of various lesions of the appendix and to study its histopathological features.

Methods

A retrospective study was conducted in Sri Lakshmi Narayana Institute of Medical Sciences, Puducherry, India after obtaining Ethics Committee approval. This study included the appendectomy specimens over two years from January 2019 to January 2021.

Negative appendectomies were defined as those procedures that are performed for the clinical diagnosis of acute appendicitis but on histopathological examination revealed no abnormality.

Appendectomies that were done as an incidental procedure during some other surgeries were excluded from this study. The specimens were received in 10% buffered formalin along with the requisition form containing a brief clinical history. A gross examination of the appendicectomy specimen was done. Lumen was looked for patency and luminal diameter was measured. Two cross-sections and one transverse section were provided for histopathology. Following grossing, dehydration and clearing were done. Finally, the paraffin-embedded tissue blocks were cut and the slides were stained with haematoxylin and eosin staining. Then the slides were examined by the histopathologists and the reports were dispatched.

Results

A total case of 180 appendectomy specimens was studied.

Among these patients 100 (55.5%) were male and 80 (44.4%) were female with a male to female ratio of 1.25:1.

Figure 1 shows the distribution of the age groups of the patients. In this study, the peak incidence of appendicitis was found between the age group of 21-40 years.

The youngest age of appendicitis case reported was 5 years and the oldest age is 63 years. About 70% occurred before the age of 40 years. Patients most commonly presented with the symptom of right iliac fossa pain (Mc Burney’s point tenderness) followed by fever and vomiting. About 90 % of acute appendicitis was diagnosed accurately by the clinicians. Whereas acute recurrent appendicitis was diagnosed appropriately only in 20% of cases. The rest of the cases of acute recurrent appendicitis was diagnosed after being subjected to examination by two pathologists. Negative appendectomies were not noted in this study.

Table 1: Histopathological findings of appendectomy specimens

Table 1 shows the histopathological findings correlated with the clinical diagnoses with which the patients were admitted. The most common diagnosis reported was acute appendicitis (45.5%) as seen in Table 1 followed by acute recurrent appendicitis (23.8%). Periappendicitis was alone noted in 3.3% of the cases. In this study, incidental findings were noted in 3 of the cases which encompass 2 cases of appendicitis with Enterobius vermicularis (Figure 2). In Enterobius vermicularis appendicitis, both cases show acute and chronic inflammatory infiltrate comprising of eosinophils, lymphocytes, and plasma cells involving the entire thickness of the appendiceal wall.

One case of tuberculosis of the appendix was reported (Figure 3).

There was also a single case of fibrous obliteration of the appendix (Figure 4). In the case of fibrous obliteration of the appendix, the lumen was partially occluded.

One of these cases showed lymphoid hyperplasia. No appendiceal neoplasms were encountered in this study.

Discussion

Acute appendicitis is one of the most common causes of abdominal surgery and in fact, the most common surgical procedure performed is appendectomy. As the lymphoid organ undergoes development the incidence of acute appendicitis increases with peak incidence at the age of 10 – 30 years. ⁴  Though the sex ratio is equal in acute appendicitis cases before puberty, the frequency begins to increase in males gradually after puberty. However, this difference almost becomes equal as age advances. It is estimated that the lifetime incidence of acute appendicitis is 7.0% overall with slight male preponderance. ^5,6

In our study, all the age groups are affected, with maximum cases reported at the age group of 21-40 years. Similar findings were observed by Shreshta et al and Sinha et al. ^7,8 In this study, the male to female ratio is 1.25:1, with male preponderance as observed by Kulkarni et al. ⁹

The average length of the appendix was 5 cm in length. In some of the cases, we received appendectomy specimens in 2-3 segments. In our study, acute appendicitis constituted the major number of cases. The microscopic criteria for diagnosis of acute appendicitis are infiltration and proliferation of neutrophils which extends from mucosa up to muscularis propria. The degree of inflammation is directly proportional to the severity of the infection. The inflammation can extend up to the periappendicular tissue if the disease progress.¹⁰

The pathogenesis of appendicitis most likely stems from the obstruction of the appendiceal lumen. However, the aetiology of this obstruction varies among different age groups. This obstruction may be caused by lymphoid hyperplasia, infections, faecoliths, and benign or malignant tumours. When appendicitis has its root cause to obstruction then as a result of an obstruction in the appendicular lumen there will be an increase in intraluminal and intramural pressure which results in small vessel occlusion and lymphatic stasis. As a result, the appendix becomes distended and gets filled with mucus. Further due to lymphatic and vascular compromise, the wall of the appendix becomes ischemic and necrotic. In the obstructed appendix, there will be bacterial overgrowth with aerobic organisms predominantly involved in early appendicitis and mixed aerobes and anaerobes involved later in the course. Common organisms involved include Escherichia coli, Peptostreptococcus, Bacteroides, and Pseudomonas. The most common complication of appendicitis is perforation and abscess formation which is mainly due to the significant inflammation and necrosis that occur.¹¹ In this study the incidence of perforation with acute appendicitis is 56%, Cooley B reported 33%, ¹² while Kulkarni et al reported 49% ⁹ presenting with perforation in acute appendicitis cases. The incidence of perforation is slightly higher compared to other studies the reason of which could be due to delay in seeking medical help.

The differential diagnoses of acute appendicitis encompass acute mesenteric adenitis, acute gastro-enteritis, intussusception, Crohn’s enteritis, perforated peptic ulcer, ureteric stones, and gynaecologic conditions like pelvic inflammatory disease or ruptured ectopic pregnancy.²

Acute recurrent appendicitis marked the second largest category of diagnosis constituting 23.8% (43 cases) in the present study. The criteria for diagnosis of Acute recurrent appendicitis were infiltration of active chronic inflammation which extends from the mucosa up to the serosal layer by lymphocytes and plasma cells. ¹³ About 20 out of 43 cases of acute recurrent appendicitis showed hyperplastic lymphoid follicles with prominent germinal centres which indicates stimulated B cell-mediated immune response. This finding is in concordance with the findings of Kulkarni et al. ⁹

In this study, the total cases of periappendicitis are 49 cases, of which 32 cases are associated with acute appendicitis and 11 cases are associated with Acute recurrent appendicitis. Periappendicitis was alone noted in 6 of the cases. In a study by Porras et al the no of periappendicitis cases associated with acute appendicitis was 36 cases.¹⁴ The increase in the number of cases of periappendicitis may be due to a lack of early intervention.

Fibrous obliteration of the appendix is considered as a segment of the aging process which results in the loss of normal appendiceal mucosa, submucosa, and Peyer patches which are the group of lymphoid tissue within the submucosa. They are eventually replaced by fibrotic tissues. In most cases, fibrous obliteration of the appendix mimics acute appendicitis. However, this condition is not common to clinicians or radiologists and its imaging findings are rarely seen.¹⁵ Microscopically, the luminal wall is replaced by fibrous tissue infiltrated by chronic inflammatory cells which is usually accompanied by nerve cells & neuroendocrine cell proliferation. Neural tissue proliferation can be identified by immunohistochemistry using neuron-specific enolase & S-100 protein.¹⁶ In this study, we had one case of fibrous obliteration of the appendix. The study by Kulkarni et al had 15 cases.⁹ The decreased number of cases can be due to the limited sample size.

The incidental finding of Enterobius vermicularis in the appendix usually produces symptoms resembling acute appendicitis. In this study, we reported two cases of E. vermicularis presenting with features of acute appendicitis. Globally, the reported incidence of Enterobius vermicularis infestation in patients with symptoms of appendicitis ranges from 0.2% to 41.8%.¹⁷ The clinical picture and histomorphological findings of

Enterobius Vermicularis appendicitis is highly variable. Hence, all appendectomy specimens must be carefully examined for the presence of the parasite, so that appropriate antihelminthic medication is started.¹⁸

The most common sites of Tuberculosis in the abdomen are the Terminal ileum, ileocaecal junction, and peritoneum. The involvement of the appendix is quite rare though it lies close to the ileocecal junction. In this scenario, Primary appendicular TB as an isolated form is even rarer. Globally, the estimated incidence of abdominal TB among all cases of TB is 1–3%.¹⁹ It was thought that ingestion of contaminated milk with TB bacilli, Mycobacterium Bovis, was the reason behind primary Gastrointestinal Tuberculosis but now boiled milk is usually consumed in developing countries and pasteurized milk is consumed in the west which makes it not likely for the ingestion of bacilli. ²⁰ The main reason behind the rare involvement of isolated appendix is minimal exposure of the intestinal contents with the luminal mucosa of the appendix despite being close to the ileocaecal junction which is the common site for tuberculosis in the abdomen. ²¹

In this study, we had a single case of Tuberculosis appendicitis, which was an incidental finding. The patient had a history of abdominal pain and weakness. The clinical diagnosis made was Acute recurrent appendicitis and appendectomy was performed. Histopathological examination revealed transmural infiltration by inflammatory cells with caseating necrosis and granuloma formation. Langhans giant cells were also noted. However, tubercle bacilli were not appreciated by the Ziehl-Neelson stain. The diagnosis of tuberculous appendicitis was given and the patient was started on antitubercular treatment. Sinha et al reported a single case of tuberculous appendicitis which was also an incidental finding. ⁸

Lau et al reported 8 % of cases as gangrenous appendicitis. ²² In this study, the rate of gangrenous appendicitis is found to be just 1.5% of all cases. The discrepancy could be due to a smaller sample size or early intervention.

In conclusion, histopathological examination of appendectomy specimens is mandatory since they help not only to confirm the diagnosis of acute and Acute recurrent appendicitis but also play an important role in identifying incidental findings which mandate further treatment. It is not possible to make a definitive diagnosis pre-operatively or during surgery, hence histopathological examination is the confirmative diagnostic tool for all appendectomy specimens.

Authors’ Contributions
Priyatharsini Pari provided gross and histopathological opinion and collected and typed the data. Bharathi Udhayakumar and Priyadharisini Jayakumar compiled the data.

Author Disclosure Statement
No competing financial interests exist.

Funding Information
No funding was received for this article.

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Fig 1: Age and sex distribution of the cases

Figure 2: Microphotograph showing Enterobius vermicularis in the lumen of the appendix (H&E / 10X)

Figure 3: Microphotograph showing well-formed granuloma and Langhans Giant cells (H&E / 10X) (Inner box shows caseous necrosis)

Figure 4: Microphotograph showing fibrous obliteration of the appendix (H&E / 10X)