EP1047 - Metastatic pancreatic cancer presenting as a pseudocyst with partial large bowel obstruction

Purpose/Background: Pancreatic cancer and pancreatic pseudocyst are not uncommon diseases. However, a pancreatic pseudocyst as a sign of pancreatic cancer is rare. In this report, we consider a patient with no history of pancreatitis who presented with a 2 cm pancreatic pseudocyst and partial large bowel obstruction, discovered to be an unusual case of metastatic pancreatic ductal adenocarcinoma.

Methods/Interventions: N/A

Results/Outcomes: A 74-year-old female with a history of hypertension presented with abdominal pain and worsening oral intake. She was found to have a 2 cm pseudocyst and transverse colitis on an outpatient computed tomography (CT) scan. A repeat CT with rectal contrast on admission showed persistent thickening of the splenic flexure and upstream obstruction and dilation of the cecum to 10 cm along with an unchanged pancreatic pseudocyst. The patient was unable to tolerate the bowel prep for a colonoscopy, exhibiting worsening obstructive symptoms. She underwent exploratory laparotomy, where a firm and fixed mass was found in the splenic flexure, unresectable due to significant fixation to the retroperitoneum with concern for pancreatic involvement. The cecum was significantly dilated with extensive serosal tears. Lesions were noted throughout the colon: a mass in the mid transverse colon that appeared intraluminal but not obstructing, a mass in the mid rectum with possible stricturing, and a mass in the terminal ileum. The decision was made to proceed with a right colectomy with end ileostomy and creation of a mucous fistula.

To determine the primary tumor origin, the patient underwent additional endoscopic evaluation. Endoscopic ultrasound demonstrated pancreatic parenchymal abnormalities in the head, genu, and body. An irregular mass was identified in the body and tail measuring 3 x 4 cm. Sonographic evidence suggested invasion into the splenic artery and superior mesenteric vein. Fine needle aspiration was suspicious for adenocarcinoma, and biopsy of the pancreas confirmed pancreatic adenocarcinoma with distinct regions of intraductal papillary mucinous neoplasm. A flexible sigmoidoscopy showed a frond-like, infiltrative, completely obstructing mass in the recto-sigmoid colon with biopsy confirming a moderately differentiated pancreatic ductal adenocarcinoma. While this presentation for metastatic pancreatic cancer is atypical, the tumor immunoprofile, coupled with an elevated serum CA 19-9 and normal CEA, favored metastatic pancreatic adenocarcinoma.

Midline wound breakdown, an enterocutaneous fistula, and a small bowel obstruction complicated the post-operative course. After a goals of care discussion, the patient ultimately chose to undergo placement of a palliative decompressive percutaneous endoscopic gastrostomy tube and home hospice care.

Conclusion/Discussion: We present a rare case of metastatic pancreatic ductal adenocarcinoma that initially appeared as a solitary pancreatic pseudocyst with clinical signs of a large bowel obstruction. Pancreatic ductal adenocarcinoma is an aggressive tumor with poor outcomes and, as in this patient, is often diagnosed at an advanced stage. This report emphasizes the importance of undergoing a comprehensive work-up, including imaging studies, biopsies, and immunohistochemical stains, for accurate diagnosis and treatment.

Figure 1. Cross-sectional imaging and endoscopic findings.
CT (A) axial view showing the pancreatic pseudocyst and (B) coronal view showing a dilated cecum and transverse colon. (C) Flexible sigmoidoscopy revealing a malignant-appearing tumor in the rectosigmoid colon, biopsied.
Figure 2. Endoscopic ultrasound findings.
Masses were found in the (A) tail, (B) body, and (C) head of the pancreas.