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An association between ampullary adenoma and adenocarcinoma has been reported previously.1 However, we believe that this is the first report of the synchronous occurrence of adenocarcinoma of the ampulla of Vater and a gastrointestinal stromal tumour (GIST).
A 41 year old woman was admitted to our hospital for the evaluation of jaundice. Her liver function tests were as follows: alanine aminotransferase, 37 U/litre (normal range, 0–31); aspartate aminotransferase, 32 U/litre (normal range, 0–32); alkaline phosphatase, 598 U/litre (normal range, 0–240); total bilirubin, 203.2 mg/litre (normal range, 1–11); direct biluribin, 151.6 mg/litre (normal range, 0–3).
Ultrasonography, computed tomography, and magnetic resonance imaging studies showed intrahepatic and extrahepatic bile duct dilatation. Termination of the common bile duct at the distal end by a mass was noted (fig 1). The initial radiological differential diagnosis included pancreatic head tumour and periampullary carcinoma.
Endoscopic procedures were not performed before surgery. Pancreaticoduodenectomy, cholecystectomy, and distal gastrectomy with lymph node dissection were performed.
Grossly, there was a polypoid tumour (1.5 × 1.5 × 1 cm) at the duodenal ampulla with a solid subserosal tumour (3 × 3 × 2 cm) in the second portion of the duodenum (fig 2). On cut section, there was no transition between these two different tumours and no invasion of surrounding tissues and pancreas.
Histologically, the tumours showed a moderately differentiated adenocarcinoma associated with a villous adenoma, which was limited to the ampulla of Vater and a GIST (figs 3 and 4). The GIST was sharply demarcated from the surrounding tissue and it was mainly located at the serosa and muscular layers. Cytologically, the tumour cells had spindle shaped, blunt ended or oval nuclei, with evenly distributed chromatin and moderate pleomorphism; the cells exhibited a fascicular or storiform growth pattern, and had invaded the submocosal layer. Nine atypical mitotic figures for each 10 high power fields (HPF) were present. Immunohistochemically, the tumour cells of the GIST showed diffuse and strong positive immunoreactivity against CD117 (T595; 1/20 dilution; Novacastra, Newcastle, UK), CD34 (QBEND/10; 1/50 dilution, Dako, Glostrup, Denmark).
Stromal tumours involving the small intestine are far less common but seem to have greater malignant potential.2 The expression of CD117 has emerged as the most important defining feature and probably the gold standard for diagnosing GISTs.2 High mitotic index (more than five mitoses/10 HPF) and larger tumour size (> 5 cm) are generally accepted as the best indicators of malignancy in GIST.2 Despite the small size of the tumour, nine atypical mitotic figures/10 HPF, submucosal invasion, and mild pleomorphism of the tumour cells were present in our case.
The possible cause of multiple malignancies include: reduced immunological competence, constitution, genetic factors, chemotherapy, radiation exposure, surgery, or smoking.3 In our patient, a family history of malignancy and other risk factors were not present. It can also be hypothesised that the duodenum was influenced by the same unknown carcinogen, resulting in a simultaneous proliferation of different cell lines (epithelial and stromal cells).4
The literature includes case reports of gastric collision tumour composed of GIST intermixed with adenocarcinoma, synchronously occurring GIST and carcinoid tumour, GIST and lipoma, and GIST and mucosa associated lymphoid tissue lymphoma.4,5 To our knowledge, our case is the first report of the synchronous occurrence of adenocarcinoma of the ampulla of Vater with a GIST.