Pancreatic cancer secondary to intraductal papillary mucinous neoplasm with collision between gastric cancer and B-cell lymphoma: A case report

BACKGROUND: Patients with intraductal papillary mucinous neoplasm (IPMN) have an increased risk of pancreatic and extrapancreatic malignancies. Lymphomas are rare extrapancreatic malignancies, and in situ collisions of early gastric cancer and diffuse large B-cell lymphoma (DLBCL) are even rarer. Here, we report the first case of pancreatic cancer comorbid with in situ collision of extrapancreatic malignancies (early gastric cancer and DLBCL) in a follow-up IPMN patient. Furthermore, we have made innovations in the treatment of such cases. CASE SUMMARY: An 81-year-old Japanese female diagnosed with IPMN developed elevated carbohydrate antigen (CA) 19-9 levels during follow-up. Because her CA19-9 levels continued to rise, endoscopic ultrasound (EUS) was performed and revealed a suspicious lesion at the pancreatic tail. However, lesions in the pancreas were not found by computed tomography, magnetic resonance imaging, or endoscopic retrograde cholangiopancreatography. To make an exact patho-logical diagnosis, EUS-guided fine needle aspiration was performed. To our supprise, early gastric cancer was found in preoperative gastroscopy. The gastric cancer was completely resected through endoscopic submucosal dissection before postoperative pathology identified early adenocarcinoma collided with DLBCL. Subsequent EUS-guided fine needle aspiration provided pathological support for the pancreatic cancer diagnosis, and then laparoscopic distal pancreatectomy and splenectomy were performed. CA19-9 levels returned to normal postoperatively. CONCLUSION: Endoscopic submucosal dissection is appropriate for submucosal lymphomas in patients intoleratant of chemotherapy. EUS can detect small IPMN-related pancreatic tumors.