Ampullary small cell neuroendocrine carcinoma is extremely rare and has only been documented in few case reports and retrospective study. The patients with ampullary small cell neuroendocrine carcinoma usually presented after the age of 60 years, and a male predilection was observed. Only two cases of a small cell neuroendocrine carcinoma associated with an adenoma have been described in a retrospective study. There has been no radiology report describing the imaging features of these coexisting tumors of the ampullary region.
An article published on August 7, 2008 in the World Journal of Gastroenterology addresses this report. The medical team composed of Dr. Sun JH and his colleagues from Second Affiliated Hospital and Sir Run Run Shaw Hospital, Zhejiang University revealed the novel case based on the clinical, histopathological and radiological features.
A 74-year-old man presented with a 3 week history of abdominal discomfort and jaundice. Abdominal ultrasonography, computed tomography (CT) and MR cholangiogram (MRCP) showed two well-defined masses in the ampullary region, dilated bile ducts and pancreatic duct, and peripancreatic lymphadenopathy. The patient underwent Whipple's operation with local lymph node dissection. Histopathology after the operation revealed the coexistence of a small cell neuroendocrine carcinoma and a villous adenoma in the ampulla of Vater. Unfortunately, the patient died of pneumonia 3 months after the operation.
The preoperative diagnosis of these rare tumors in the ampulla is potentially problematic. CT finding of a polypous mass with a long pedicle was helpful to diagnose an adenoma. However, it may not be possible to differentiating ampullary small cell neuroendocrine carcinoma from ampullary adenocarcinoma on CT. Thus, small cell neuroendocrine carcinoma should be included in the differential diagnosis of ampullary masses especially when the patient is an old male. These tumors' associations suggest a common origin in the ampulla of Vater. It is probable that the two neoplasms originate from non-neoplastic multipotent stem cells that terminally differentiate into all kinds of epithelial cells including ciliated cells, mucous cells and endocrine cells.