Preoperative diagnosis of insulinoma: low body mass index, young age, and female gender are associated with negative imaging by endoscopic ultrasound.
OBJECTIVE
Endoscopic ultrasound (EUS) is a highly reliable procedure to localize insulinomas preoperatively. It has been considered to be important in planning surgical strategy, especially considering a minimal invasive approach. However, even under ideal conditions experienced examiners miss about 10-20% of insulinomas by EUS imaging.


METHODS
This retrospective study aimed to identify factors associated with negative EUS imaging. Twenty-nine consecutive patients (24 benign and 5 malignant) with sporadic pancreatic insulinomas confirmed by successful surgery and positive histopathology were included. All EUS examinations were performed by one single experienced examiner over a period of one decade.


RESULTS
Three of the tumors were not detected by preoperative EUS as they were isoechoic to the surrounding healthy pancreatic tissue; 25 could be detected as hypoechoic lesions, (including all malignant tumors), and one lesion was hyperechoic. Low body mass index (P=0.053) and young age (P=0.037) were associated with negative EUS imaging. All patients with negative imaging were females. The position on the examiner's learning curve, the diameter and location of insulinoma, and endocrine parameters (insulin concentrations and insulin-glucose ratios in the prolonged fasting test) had no influence on the success of EUS imaging.


CONCLUSIONS
Some insulinomas are missed by preoperative EUS imaging as they are completely isoechoic. A low body mass index, female gender, and young age might be risk factors for negative imaging.
Division of Endocrinology and Diabetology, Phillips University Hospital, Marburg, Germany. kannp@med.uni-marburg.de
P H
PH
Kann
D
D
Ivan
A
A
Pfützner
Th
T
Forst
P
P
Langer
S
S
Schaefer
D000328:Adult; D000375:Aging / Q000502:physiology*; D001786:Blood Glucose / Q000378:metabolism; D015992:Body Mass Index; D004724:Endoscopy; D005260:Female; D006801:Humans; D007328:Insulin / Q000097:blood; D007340:Insulinoma / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D010190:Pancreatic Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000601:surgery*; D012189:Retrospective Studies; D012307:Risk Factors; D012727:Sex Characteristics; D014463:Ultrasonography
D001786:Blood Glucose; D007328:Insulin