Primary NETs can occur anywhere in the body wherever there are enterochromaffin cells, but the gallbladder is a rare site of occurrence (<1%).5
There have been only 42 cases of gallbladder carcinoid tumours recorded in the world literature. Godwin reported only one carcinoid tumour in the gallbladder among 2837 carcinoid tumours from the gastrointestinal tract.6
Capella et al
reported 19 cases (0.2%) of gallbladder carcinoids in their analysis of 8305 cases of carcinoids of all sites.7
A review by Khetan et al
showed that in all the cases examined (n=22), the diagnosis was made postoperatively or during postmortem.3
Our patient was diagnosed after surgery, during routine histopathological examination. It is interesting to know that the incidence of multiple carcinoids in the same patient may be ~10–33%, with the small bowel being the most common site (82%).8,9
In the presented case study, there was no metastasis anywhere else in the body. Due to increased incidence of gastroenteropancreatic NET (GEP-NETs), the World Health Organisation (WHO) used a prognosis-oriented definition to provide a common framework.10,11
Though the term “carcinoid tumour” is a well-recognised terminology, it may not cover all tumours arising from neuroendocrine cells present all over the body. Hence the WHO used neuroendocrine tumour or neuroendocrine carcinoma to describe these conditions instead of carcinoid tumours.12
In addition, the European Neuroendocrine Tumour Society (ENETS) proposed guidelines on Tumour–Node–Metastasis (TNM) classification for foregut, midgut and hindgut NETs.13,14
However, clear staging guidelines for NETs arising from the gallbladder have not been promulgated, perhaps because of the rarity of this condition.
While the incidence of carcinoid disease in general appears to have increased due to improved diagnostic technology, more precise specific antibodies in immunohistochemistry and awareness among clinicians and pathologists, they are commonly overlooked or misdiagnosed in uncommon sites such as the gallbladder. Following the diagnosis of carcinoid tumour in the gallbladder, further investigations should be undertaken to detect a potential concurrent lesion elsewhere or a distant metastasis. Laparoscopic curative resection is possible if the tumour is confined within the gallbladder wall.
A consensus TNM staging would be helpful for the future management of NETs arising from the gallbladder.
- The incidence of neuroendocrine tumours is increasing, due to improved diagnostic tests.
- Laparoscopic curative resection is possible if the tumour is confined to the gallbladder wall.
- Following the diagnosis of neuroendocrine tumour in the gallbladder, further investigations should be undertaken to detect a potential concurrent lesion elsewhere or a distant metastasis.
- A staging system should be developed to assist in the future management of this uncommon condition.