title: Giant malignant insulinoma which developed from a non-functioning pancreatic tumor over a long period of time.
abstract: Insulinomas are the most common hormone-producing pancreatic neuroendocrine tumors (NETs), which are usually benign, solitary and small. We describe herein a patient with a giant insulinoma (>10 cm in diameter) with concomitant thyroid tumor as detected by Somatostatin receptor scintigraphy (SRS). A 50-year-old man presented hypoglycemic symptoms 20 years after the first detection of a pancreatic tumor, which was ameliorated by administration of a somatostatin analogue, octreotide. SRS showed abnormal uptake by the insulinoma as well as by the thyroid tumor. RT-PCR and immunohistochemical study revealed abundant expression of somatostatin receptor (SSTR)-1, -2, and -5 in his insulinoma and SSTR-1 and -2 in his thyroid follicular neoplasm. This is a rare case of a slow-growing pancreatic well-differentiated neuroendocrine carcinoma over a long period of time to become a symptomatic giant insulinoma. Furthermore, SRS proves to be a useful tool for localization of insulinoma as well as concomitant thyroid neoplasm with predominant expression of SSTRs.
authors.affiliation: Department of Clinical and Molecular Endocrinology, Tokyo Medical and Dental University Graduate School. tsugiyama.cme@tmd.ac.jp
authors.forename: Toru
authors.initials: T
authors.lastname: Sugiyama
authors.forename: Ryuji
authors.initials: R
authors.lastname: Kouyama
authors.forename: Yuji
authors.initials: Y
authors.lastname: Tani
authors.forename: Hajime
authors.initials: H
authors.lastname: Izumiyama
authors.forename: Takumi
authors.initials: T
authors.lastname: Akashi
authors.forename: Seiji
authors.initials: S
authors.lastname: Kishimoto
authors.forename: Shigeki
authors.initials: S
authors.lastname: Arii
authors.forename: Yukio
authors.initials: Y
authors.lastname: Hirata
mesh_terms: D006801:Humans; D007340:Insulinoma / Q000175:diagnosis* / Q000209:etiology; D008297:Male; D008875:Middle Aged; D010190:Pancreatic Neoplasms / Q000150:complications / Q000175:diagnosis*; D013964:Thyroid Neoplasms / Q000175:diagnosis* / Q000209:etiology; D013997:Time Factors