title: A large malignant insulinoma: case report with endosonographic, immunohistochemical and ultrastructural features.
abstract: Malignant insulinoma in the beta cells of the pancreatic islet is rare and usually presented as hypoglycemia. We report a case of large malignant insulinoma in a 53-year-old Korean woman. A presumptive clinical diagnosis was made before surgery, based on the high plasma insulin-to-glucose ratio and a large solitary heterogeneous pancreatic mass by abdominal computed tomography and endosonography. The tumor measured 5.8 x 4.7 x 4.5 cm in dimension and showed capsular invasions and metastases in two of four peripancreatic lymph nodes. The tumor cells were strongly immunoreactive to insulin and had a high Ki-67 labeling index (13%) and atypical membranous electron-dense granules, ranging from 120 to 400 nm in diameter, in the cytoplasm on electron microscopy. The patient was treated by distal pancreatectomy with splenectomy and rapidly recovered without neurohypoglycemic symptoms. This case showed not only lymph node metastases, the most reliable parameter for malignancy in pancreatic endocrine tumors, but also other valid diagnostic clues, such as high Ki-67 labeling index, heterogeneous enodosonographic findings, capsular invasions with large tumor and pure atypical secretory granules.
authors.affiliation: Department of Internal Medicine, College of Medicine, Dongguk University, Gyeongju, Korea.
authors.forename: Chang Hwa
authors.initials: CH
authors.lastname: Lee
authors.forename: Goo
authors.initials: G
authors.lastname: Lee
authors.forename: Dong Hoon
authors.initials: DH
authors.lastname: Kim
authors.forename: Nam
authors.initials: N
authors.lastname: Kim
authors.forename: Sung Ja
authors.initials: SJ
authors.lastname: Kim
authors.forename: Chang Woo
authors.initials: CW
authors.lastname: Lee
authors.forename: Kuk Hyun
authors.initials: KH
authors.lastname: Song
mesh_terms: D001707:Biopsy, Needle; D019160:Endosonography; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007150:Immunohistochemistry; D007340:Insulinoma / Q000175:diagnosis* / Q000601:surgery*; D007515:Islets of Langerhans / Q000473:pathology / Q000648:ultrastructure; D007723:Korea; D008875:Middle Aged; D009367:Neoplasm Staging; D010180:Pancreatectomy / Q000379:methods*; D010186:Pancreatic Function Tests; D010190:Pancreatic Neoplasms / Q000175:diagnosis* / Q000601:surgery*; D018570:Risk Assessment; D016896:Treatment Outcome