Fangyuan Jin-Dominguez, MD, Dina Ahmad, MD, Ashley Faulx, MD, Amitabh Chak, MD
University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, OH
Introduction: We report a case of an incidentally found asymptomatic pancreatic tail cyst that rapidly grew from 1 cm to 3.4 cm in a 3-month period. The final diagnosis is metastatic pancreatic neuroendocrine tumor (NET).
Case Description/Methods: A 72-year-old male was referred for EUS to evaluate an incidental 13 mm pancreatic tail cyst found on CT chest. He was asymptomatic and had no prior history of pancreatitis or family history of pancreatic cancer. EUS showed a 10 mm microcystic lesion in the pancreatic tail with a central echogenic area suggestive of a serous cystadenoma (Figure 1-A). CT performed three months later for follow up on lung nodules demonstrated interval enlargement of the pancreatic lesion to 3.4 cm. The lesion appeared isodense and solid. EUS confirmed the rapid increase of size from 1 to 3 cm (Figure 1-B). FNA was performed and cytology was interpreted as malignant cells derived from adenocarcinoma. Serum CA 19-9 was 1.88 U/ml. Pancreatic protocol CT (Figure 2) found a new 4 cm low-attenuation liver lesion within segment IV B. Biopsy of the liver lesion was negative for neoplasm. Patient was referred to surgery and the plan was to perform laparoscopy, excisional wedge liver biopsy, followed by distal pancreatectomy and splenectomy if the wedge biopsy did not show metastatic adenocarcinoma. Intraoperatively, a very small subcapsular lesion was excised from the liver and sent for frozen section to pathology. By the time pathology came back reporting a 2.5mm lesion with evidence of poorly differentiated carcinoma, the surgeon has already transected the splenic artery. Therefore, distal pancreatectomy and splenectomy were completed. Final pathology reported grade 3 well differentiated NET of distal pancreas with metastasis involving 1/13 LNs and liver, negative margins achieved. Ki-67 labeling index was 75% (Figure 3). Patient has had no sign of cancer progression six months after the initial diagnosis.
Discussion: Our interesting case raises many important points to consider; Pancreatic NET can uncommonly have a cystic component. Additionally, pancreatic NET can mimic pancreatic adenocarcinoma and cytology alone cannot reliably differentiate between high grade neuroendocrine tumors and adenocarcinoma. This patient could have been erroneously treated for metastatic adenocarcinoma. Endosonographers should be alert to this possibility when a presentation is not typical for adenocarcinoma and/or the lesion has cystic components with a smooth border.
Citation: Fangyuan Jin-Dominguez, MD, Dina Ahmad, MD, Ashley Faulx, MD, Amitabh Chak, MD. P0974 - SMALL PANCREATIC CYST PROGRESSED TO METASTATIC PANCREATIC NEUROENDOCRINE TUMOR IN THREE MONTHS. Program No. P0974. ACG 2019 Annual Scientific Meeting Abstracts. San Antonio, Texas: American College of Gastroenterology.