Laparoscopic resection of a gastrointestinal stromal tumour in a Meckel's diverticulum.

A Meckel's diverticulum (MD) is a congenital abnormality of the gastrointestinal tract which is estimated to be present in 2% of the population. Gastrointestinal stromal tumours (GISTs) are rare, soft-tissue tumours which represent 0.1%-3% of all gastrointestinal tumours. The association of an MD and a GIST is extremely unusual since fewer than 3% of MD harbour primary neoplasms and most of these neoplasms are carcinoid tumours. While MDs may remain asymptomatic throughout life, a small proportion may be complicated by occult gastrointestinal bleeding, inflammation, perforation and small bowel obstruction. A tumour in an MD may be asymptomatic or can cause vague abdominal pain and small bowel obstruction if it is larger in dimension. The authors present a rare case of a 5.5 cm GIST in an MD that was completely resected through a laparoscopic approach.

INTRODUCTION

A Meckel's diverticulum (MD) is a remnant of the omphalomesenteric or Vitello-intestinal duct which in the embryo connects the primitive gut to the yolk sac. It is present in 2% of the population, is on average 2 inches long and arises from the anti-mesenteric border of the distal ileum, approximately 60 cm from the ileocaecal valve.[1] It frequently remains asymptomatic throughout life, particularly if it has a broad base. However, symptomatic presentations of MD in adults are bleeding (38%), small bowel obstruction (34%), inflammation (28%) and perforation (10%).[2]

Tumours arising from an MD are uncommon, found in 0.5%–3.2%, and are usually incidental.[3] The majority of neoplasms in MD are carcinoid, with few being gastrointestinal stromal tumours (GISTs).[3] Herein, we present a case of a symptomatic GIST arising from an MD that was fully excised laparoscopically.

CASE REPORT

A 74-year-old man was investigated for a 2-month history of change in bowel habit towards loose stools associated with abdominal pain. He had a background hypertension, hypercholesterolaemia and gastro-oesophageal reflux disease.

Clinically, there were no palpable abdominal masses, and he had normal blood results. He had a colonoscopy where only a 2 mm polyp (tubulovillous adenoma with low-grade dysplasia) was found in the descending colon and completely excised. Contrast-enhanced computed tomography (CT) of the abdomen and pelvis revealed a 5 cm × 4.5 cm lobulated mass anterior and superior to the bladder and on magnetic resonance imaging (MRI) the mass appeared fibrinous in architecture and lying within a small bowel loop.

He underwent diagnostic laparoscopy where the lesion was found to arise from an MD. Figure 1 demonstrates the laparoscopic findings. A 5 mm port was sited in the patient's left iliac fossa, and this was used to place a grasper to manipulate the mass. The mass was not necrotic, perforated or causing small bowel obstruction. It was delivered through a 5 cm Pfannenstiel incision and a wedge resection was undertaken followed by primary side-to-side stapled ileoileal anastomosis. Figure 2 demonstrates the resected specimen.

Figure 1

(a) Meckel's diverticulum containing lobulated mass, (b) Meckel's diverticular mass manipulated with grasper

Figure 2

Resected Meckel's diverticular mass with 5 cm margin of small bowel on either side of the lesion and associated small bowel mesentery

The patient made a rapid recovery and was discharged the following day. The histology confirmed this to be a 5.5 cm spindle type GIST with a high prognostic index (size >5 cm; mitotic index >5/5 mm square). There was no evidence of necrosis or lymphovascular invasion, and the margins were clear. The patient was subsequently reviewed by oncology and started on a 3-year course of imatinib.

DISCUSSION

GIST in an MD is an extremely rare entity. GISTs are tumours of mesenchymal origin and account for <1% of all gastrointestinal malignancies.[3] While 20% of GISTs are asymptomatic, symptoms attributable to GISTs include bleeding, which presents in 50% of symptomatic cases, abdominal pain or a palpable abdominal mass.

For diagnostic purposes, endoscopic ultrasound scanning with fine-needle aspiration cytology carries a 97% diagnostic accuracy in experienced hands. Microscopically, GIST cells are spindle-shaped (70%), round-bodied (epithelioid type, 20%) a mixture or pleomorphic in morphology.[4] Most (97%) GISTs stain positively in immunostaining for the KIT protein (the CD117 antigen, an epitope of the KIT tyrosine kinase), exhibiting a diffuse, local or mixed staining pattern.[5] CT scanning of the chest, abdomen and pelvis is the modality of choice for staging and MRI can be useful in delineating the relationships of the tumour to adjacent organs.

Surgery is the mainstay treatment for resectable GISTs, and this may be undertaken through an open or laparoscopic approach. Nodal metastases are extremely rare and therefore routine extended lymph node dissection is not undertaken. Imatinib, a tyrosine kinase receptor inhibitor, is used to shrink large GISTs to make them amenable to complete resection and in metastatic GIST. It inhibits the kinase activity of KIT, causing apoptotic cell death of GIST cells.[6] Adjuvant Imatinib is recommended for a minimum of 3 years in patients who have a completely resected, high-risk GIST.

The important prognostic factors are tumour size, the symptoms at diagnosis, the organ of origin (small bowel GISTs have the worst prognosis) and mitotic count. Most GISTs <2 cm have negligible mitotic activity and are considered very low risk.[6] Large tumours have a much poorer prognosis, even after complete resection.[7]

CONCLUSION

While GISTs arising from MD are uncommon, they can be successfully managed through a laparoscopic approach with good outcomes. Imatinib may be used as adjuvant therapy in patients at a high risk of disease recurrence after lesion resection.

Informed consent

Written informed consent was obtained from the patient for publication of this report and any accompanying images.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given his consent for his images and other clinical information to be reported in the journal. The patient understands that name and initial will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.