Meckel's diverticulum with neuroendocrine tumor: unusual

presentation

Diego Fernando Salcedo Miranda^1,2, Gabriel Herrera², Rafael Garcia Duperly²,

Maria Paula Forero Rios¹

1 Universidad El Bosque

2 Fundación Santa Fe de Bogotá

ABSTRACT

Meckel's diverticulum is a congenital malformation that usually presents as an incidental finding. It can be complicated by inflammatory processes, with non-specific abdominal symptoms which delay its timely diagnosis. Although the incidence of malignant neoplasms in these diverticula is low, neuroendocrine tumors are the most representative.

We present the case of a 72-year-old female patient who consulted for abdominal pain and melenic bowel movements, with multiple intrahepatic nodules suggestive of neuroendocrine tumors and an incidental intraoperative finding of acute Meckel's diverticulitis with peridiverticular metastasis of a neuroendocrine tumor.

Keywords: Meckel diverticulum, diverticulitis, colectomy, neuroendocrine tumor.

INTRODUCTION

Meckel's diverticulum is a congenital malformation that usually presents as an asymptomatic incidental finding. It can be complicated by inflammation, intestinal occlusion or bleeding. The incidence of malignant neoplasms in these diverticula is low, with neuroendocrine tumors being the most common, especially in elderly patients.

CASE

A 72-year-old female, with no pathological history of interest except arterial hypertension under pharmacological management, consulted for diffuse abdominal pain and melenic stools. The abdomen was tender on palpation in the mesogastrium, without masses or peritoneal signs.

The laboratory revealed an increased white blood cell count (12.8x109/L), with normal C-reactive protein, lactate, and hemoglobin.

The abdominal ultrasound was normal, however, the abdominal computed tomography showed two liver nodules, one measuring 39 mm in segment VII, and another in the left lobe, suggestive of metastatic neuroendocrine tumors (Fig. 1). Treatment was started with 100 mcg of octreotide, tolerated without complications.

The esophagogastroduodenoscopy and the total colonoscopy were normal, however the patient remained symptomatic, for which a diagnostic laparoscopy was decided, with the incidental finding of a Meckel's diverticulum with a neuroendocrine tumor (Fig. 2).

Oncologic right colectomy, extended proximally to include Meckel's diverticulum and foci suggestive of neuroendocrine tumor was performed, with laterolateral ileotransverse anastomosis (Fig. 3).

Figure 1. Contrast-enhanced abdominal

tomography on admission showing liver

involvement.

Histopathology reported 30 negative lymph nodes and 1 positive peridiverticular node for neuroendocrine tumor metastasis. Immunohistochemical stains for chromogranin and synaptophysin expressed deeply in tumor cells. KI67 was performed on the tumor and the metastatic lymph node.

Figure 3. Right colectomy specimen extended proximally to involve Meckel's diverticulum and compromised mesentery.

DISCUSSION

Meckel's diverticula are the most common malformation of the gastrointestinal tract, occurring in approximately 2% of the population with an incidence of 1.44 per 10 million people per year.

They are the result of incomplete atrophy of the omphalomesenteric duct, located at the antimesenteric edge of the small intestine, more specifically the distal middle ileum, which means that approximately 50% is made up of ectopic gastric and pancreatic tissue, and even rarer tissues such as duodenal, hepatic and endometrial.¹

They are usually diagnosed in childhood, up to 60% in children under 2 years of age, and to a lesser extent in people over 70 years of age.¹ Patients usually present some symptom, while 16% remain asymptomatic, becoming an incidental finding.²

The non-specific symptoms and signs (abdominal pain, hematochezia) are related to the complication of the diverticulum. The most common complication in adults is intestinal obstruction followed by diverticulitis.² Even the symptoms become so indistinguishable that the main differential diagnoses are appendicitis, peptic ulcer, biliary colic, and gastroenteritis.³

Computed tomography (CT) scan is the diagnostic imaging study of choice since it allows identifying the presence of the diverticulum and its complications; however, on many occasions it is not visualized or tends to be confused with a normal intestinal loop, as occurred in this case.

Malignant neoplasms of Meckel's diverticula are even rarer, with an incidence of up to 4.9%. Neuroendocrine tumors are the most representative, especially in patients in the seventh and eighth decades of life, as reported by Andrade et al.,(4) who also demonstrated the low incidence in individuals under 40 years of age. In our patient, both the abdominal pain and the melenic stools were secondary to a mesenteric desmoplastic reaction that caused acute diverticulitis.

Evidence on CT scan of multiple liver nodular lesions together with alteration of mesenteric fat adjacent to the ileum led to the suspicion of neuroendocrine tumors as the main differential diagnosis.

There are currently no management guidelines for neuroendocrine tumors in Meckel's diverticula, although it has been shown that for nodules larger than 2 cm the best approach is surgical, even in patients with multiple nodules. A lymphadenectomy alone is not recommended as definitive treatment, but rather a deep resection,⁵ as we performed in this patient.

CONCLUSION

Meckel's diverticulum neuroendocrine tumors are extremely rare. Generally asymptomatic or with non-specific symptoms, they represent a diagnostic challenge for the surgeon, and can only be diagnosed in advanced stages.

REFERENCES

1. Flórez-Leguía MK, Valencia JJ, Sierra Sierra S. Tumor neuroendocrino en un divertículo de Meckel. CES Med. 2018; 32: 294-300.

2. Burjonrappa S, Khaing P. Meckel's diverticulum and ectopic epithelium: Evaluation of a complex relationship. J Indian Assoc Pediatr Surg. 2014; 19:85-9.

3. Bandi A, Tan YW, Tsang T. Correlation of gastric heterotopia and Meckels´s diverticular bleeding in children: a unique association. Pediatr Surg Int. 2014; 30:313-16.

4. De Andrade JP, Blakely AM, Nguyen AH, Ituarte PHG, Warner SG, Melstrom LG, et al. Neuroendocrine tumors of Meckel’s diverticula: Rare but fare well. Am Surg. 2019; 85:1125-28.

5. Nies C, Zielke A, Hasse C, Rüschoff J, Rothmund M. Carcinoid tumors of Meckel's diverticula. Report of two cases and review of the literature. Dis Colon Rectum. 1992; 35:589-96.