Rare Case of Ectopic Pancreatic Cancer of the Jejunum

Abstract

Ectopic pancreatic cancer is exceedingly rare. We present a case of ectopic pancreatic cancer of the jejunum. A 75-year-old female presented with severe acute abdominal pain and nausea for a few days. Abdominal CT showed a 3.7x4.7x4.2 cm mesenteric mass encasing the superior mesenteric artery (SMA). CT-guided biopsy demonstrated adenocarcinoma of unknown primary. She was initiated on fluorouracil and oxaliplatin, but with only transient response. Surveillance CT scans did not show any evidence of metastases. She then underwent exploratory laparotomy with resection of the mass and 3rd/4th portions of the duodenum and proximal jejunum, along with vascular reconstruction of the SMA. Final pathology results demonstrated adenocarcinoma in the jejunum arising from an ectopic pancreas with tumor invading the SMA. Ectopic pancreatic tissue is estimated to be present in the gastrointestinal tract in approximately 2-15% of the population. It is thought to develop during through metaplasia of the intestinal mucosa or congenitally. Rarely does ectopic pancreas degenerate into adenocarcinoma (0.7-1.8%). It also rarely invades the mesentery, in which case the jejunum is the most commonly found location. Masses invading the mesentery typically measure 3-5 cm. Heterotopic pancreas can lead to other uncommon complications such as ulceration of mucosa, gastrointestinal bleed, intestinal obstruction, and pancreatitis. The differential diagnosis also includes gastrointestinal stromal tumors, lymphomas, and carcinoid tumors. Vitiello et al. (2017) described 29 surgical cases of ectopic pancreas, with only 37.9% of patients symptomatic prior to surgery. Only 1 of these 29 cases demonstrated pancreatic cancer. Other therapies include chemotherapy, with less information available in the literature. However, Fukino et al. (2015) did report a case of gemcitabine being effective in treating duodenal ectopic pancreatic cancer. There was also one case by Ogawa et al. (2015) which utilized tegafur/gimeracil/oteracil potassium (S-1) and particle beam therapy yielding partial remission. Overall prognosis of jejunal ectopic pancreatic cancer is unclear, however, a literature review by Yamaoka et al. (2015) noted that survival for those with distant metastases appears to range from 5-9 months.