Appendiceal Carcinoid Tumor in a 16-Year-Old Patient

Carcinoid tumor is the most common neoplasm of the appendix. There is no specific preoperative clinical presentation for appendiceal carcinoids. The usual presentation is as a classic acute appendicitis, but it can also be asymptomatic. Rarely are there symptoms of carcinoid syndrome, which may include diarrhea, flushing, bronchoconstriction, and cardiac valve diseases, especially if there is liver metastasis. Carcinoid tumors are commonly diagnosed retrospectively after histological examination of the resected appendix. Appendiceal carcinoids usually behave as benign tumors, and appendectomy alone is a sufficient treatment in the majority of cases, while for larger lesions, a right hemicolectomy should be performed. The prognosis of patients with local appendiceal carcinoids is excellent. The present study reports the case of a 16-year-old female patient that presented with severe right lower quadrant pain for 2 days. The patient underwent a successful appendectomy and recovered 2 days later. Subsequently, an appendiceal carcinoid tumor located at the proximal half towards the base of the appendix was diagnosed by histopathological examination. A follow-up examination 2 weeks after surgery revealed that the patient was well, with no discomfort. This report aims to determine the prevalence of appendiceal carcinoids in young patients and the definitive management.


Introduction
Appendiceal carcinoid lesion is a rare diagnosis found only in 0.3-0.9% appendiceal specimens. However, it is the most common type of malignant lesion of the appendix [1]. It tends to occur more commonly in females, which is attributed to a higher appendectomy rate [2]. Carcinoid tumors are derived from neuroendocrine cells of the gastrointestinal system in 73.4% of cases. Nevertheless, they are also found in the lung (25.1%), ovaries (0.5%), and the biliary system (0.2%) [3]. Carcinoid tumors spread primarily through the lymphatic system and metastasis to the liver is rare and directly related to the tumor size [4,5]. Diagnosis is made by histological findings, computed tomography radiological findings, 24-h urinary neuroendocrine metabolite 5-hydroxyindoleacetic acid (5-HIIA) levels, and 111 In-octreotide scintigraphy, also known as somatostatin receptor scintigraphy (SRS) which has 86% sensitivity in detecting carcinoid tumors and is used for staging the tumor [5]. Simple appendectomy adequately treats appendiceal carcinoids less than 1 cm in diameter, while tumors greater than 2 cm are treated with right hemicolectomy. A point of controversy is what to do for tumors in the 1 to 2 cm range. It seems that appendectomy alone is sufficient except when mesoappendiceal invasion is identified [5]. Octreotide can relieve symptoms of carcinoid syndrome and sometimes slows the progression of the disease [5]. Carcinoid tumors grow slowly, and their prognosis is excellent, with a 5-year survival rate of 85.9-100% [3,5]. A review of the literature aims to determine the prevalence of appendiceal carcinoids in young patients and the definitive management.

Case Report
A 16-year-old female patient was admitted to Dr. Sulaiman Al-Habib Hospital (Riyadh, Saudi Arabia) with a complaint of severe right lower quadrant pain for 2 days. The pain started gradually and progressively, associated with nausea, vomiting once of food content, and subjective fever, with no history of anorexia, no changes in bowel habits, and no history of a similar condition. Physical examination revealed a body temperature of 36.6 °C, blood pressure of 105/60 mmHg, and a pulse rate of 75 beats/min. During the assessment, the patient experienced light direct tenderness with rebound tenderness in the right lower abdomen. No palpable masses were observed in the abdomen. Laboratory tests were performed, yielding the following results: white blood cell count, 9.9 × 10 9 cells/l (normal range, 4-10 × 10 9 cells/l); neutrophil proportion, 76.0% (normal range, 45-80%); hemoglobin level, 143 g/l (normal range, 110-150 g/l); platelet count, 213 × 10 9 platelets/l (normal range, 100-300 × 10 9 platelets/l). In addition, abdominal computed tomography revealed a distended fluid-containing enhancing appendix in the right iliac fossa with adjacent inflammatory changes with an appearance in keeping with acute appendicitis. No adjacent collections or free air were found (Fig. 1). The patient possessed no previous medical or surgical history. The patient underwent surgery for the treatment of acute appendicitis. The appendix was identified as demonstrating hyperemia and edema. The appendix resection was completed without complications, and the patient recovered 2 days later. The specimen was sent to histopathology in formalin. At the proximal half from the base of the appendix, there was a well-differentiated grade I neuroendocrine tumor, measuring 1 cm at the maximum dimension, that had invaded the muscularis propria. No lymphovascular invasion was identified, and the tumor did not involve the margin. Coexisting acute appendicitis was also present. No further treatment was administered. A follow-up examination 2 weeks after surgery revealed that the patient was well with no discomfort. The initial multidisciplinary meeting suggested no further workup would be needed, and the surgery was curative for her case. However, she was advised to follow up with the oncology team to discuss her risks and complications.

Discussion
Acute appendicitis is the most common abdominal emergency encountered by the general surgeon. After diagnosis by histopathological examination, primary neoplasms of the appendix are identified in ~ 0.5% of all surgically removed appendices, with carcinoid tumors representing > 50% of all appendix neoplasms. Carcinoid tumors are neoplasms derived from the subepithelial neuroendocrine cells of the appendix that rarely cause metastatic disease [3]. The median age for 12 patients with carcinoid tumors analyzed by Barut [6] was 35.5 years (range 21-60), 31.5 years (21-72) for 14 patients studied by Kara and Kalaycı [7], and 29.2 years (6-82) for 5 patients in a review done by Tchana-Sato [8]. The definitive treatment of equivocal-sized tumors, i.e., 1-2 cm tumors, depends on several factors, including being a high-grade tumor at the base of the appendix, having invaded the mesoappendix, and having positive surgical margins. Any of these factors is sufficient for the surgeon to choose a right hemicolectomy instead of a simple appendectomy. Life-long follow-up is required in tumors larger than 2 cm or 1-2 with high-risk factors or if there is lymph node involvement [6].
The role of adjuvant therapies, including radiotherapy and intraperitoneal chemotherapy, is not yet part of the routine treatment of carcinoid tumors of the appendix [9]. However, the National Cancer Database (NCDB) recommends the use of adjuvant chemotherapy for goblet cell carcinoid (GCC) of the appendix, which is a combination of neuroendocrine tumor (carcinoid) and epithelial tumor (adenocarcinoma), especially when there is lymph node metastatic disease [10].

Conclusion
This report emphasizes that carcinoid tumors of the appendix can occur in children as young as 6 years of age. However, the frequently affected age group is between 29 and 35 years of age. Furthermore, this report discusses several factors that will determine the definitive treatment and the role of adjuvant therapy.
Author Contributions RMAH contributed in reporting the case. SMM contributed in writing the abstract, introduction, discussion and conclusion. WAA-N contributed in providing the abdominal computed tomography images and also as a mentor. All authors proofread the final draft.
Funding No funding was received.

Availability of Data and Material
Sulaiman Al-Habib medical group VIDA system.

Consent to the Publication All authors have agreed on publication.
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