A Case of Proinsulin-Secreting Malignant Insulinoma in an Elderly Patient with Cerebral InfarctionKana Furushima1, Atsuhito Tone1*, Akihiro Katayama1, Izumi Iseda1, Chigusa Higuchi1, Keiko Tsukamoto1, Tomohiko Mannami2, Haruhiro Yamashita2, Tetsuya Ohta3, Shuichi Nomura3, Ichiro Yamadori4, Jun Wada5, Kenichi Shikata5 and Kazuyuki Hida1
- *Corresponding Author:
- Atsuhito Tone, M.D., Ph.D
Department of Diabetes and Metabolism
National Hospital Organization
Okayama Medical Center, 1711-1 Tamasu, Kita-ku
Okayama 701-1192 Japan
E-mail: [email protected]
Received date: July 16, 2010; Accepted date: August 30, 2010; Published date: August 30, 2010
Citation: Furushima K, Tone A, Katayama A, Iseda I, Higuchi C, et al. (2010) A Case of Proinsulin-Secreting Malignant Insulinoma in an Elderly Patient with Cerebral Infarction. J Diabetes Metab 1:103. doi: 10.4172/2155-6156.1000103
Copyright: © 2010 Furushima K, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
The diagnosis of insulinoma is sometimes challenging and the symptoms of hypoglycemia may be overlooked in elderly patients with cerebrovascular diseases and higher cerebral dysfunction. Recently, there have been an increasing number of case reports of insulinoma secreting proinsulin without hyperinsulinemia. We report a case of proinsulinsecreting malignant insulinoma in a 72-year-old man with aphasia due to cerebral infarction. He manifested no apparent symptoms, although he was incidentally found to have recurrent hypoglycemia by plasma glucose measurements. The Fajans, Grunt and Turner indexes were all within normal range and the arterial stimulation and venous sampling (ASVS) test revealed no increase in insulin concentration. However, proinsulin concentration was markedly elevated (2470 pmol/l) and well-differentiated endocrine adenocarcinoma, malignant insulinoma, with 2 cm in size in the tail of the pancreas was surgically removed. The diagnosis of hypoglycemia requires careful attention especially in elderly persons and/or patients with cerebrovascular diseases. Measurement of proinsulin is recommended in the diagnosis of insulinoma without hyperinsulinemia.