Unusual magnetic resonance image of an insulinoma with extensive desmoplastic reaction.
BACKGROUND
Unlike other islet-cell tumors, insulinomas are usually benign. Most insulinomas have a high signal intensity on T2-weighted images and a low signal intensity on T1-weighted images, and are hyperintense on immediate post-gadolinium images. However, in rare cases, insulinomas may be hypointense on T2-weighted images and on immediate post-gadolinium images, mimicking a ductal adenocarcinoma.


METHODS
We present a case of a surgically proven insulinoma which was hypointense on both T2-weighted and immediate post-gadolinium T1-weighted images, but hyperintense on late phase T1-weighted images. Histopathological examination of the surgical specimen revealed a prominent desmoplastic reaction which accounted for the low signal on T2-weighted images and the contrast enhancement pattern. Delayed contrast enhancement reflects the desmoplastic component of this tumor.


CONCLUSIONS
Insulinomas with an extensive desmoplastic reaction may appear hypointense on T2-weighted images with minimal enhancement on immediate post-gadolinium images. Late phase fat-suppressed T1-weighted post-gadolinium images may be useful in the detection of such tumors.
Inan
Nagihan
N
Department of Radiology, School of Medicine, University of Kocaeli, Turkey. nagihaninan@yahoo.com.tr
Arslan
Arzu
A
Akansel
Gur
G
Okay
Erdem
E
Gurbuz
Yesim
Y
D000328:Adult; D003094:Collagen / Q000378:metabolism; D003238:Connective Tissue / Q000378:metabolism / Q000473:pathology*; D005682:Gadolinium; D006801:Humans; D007340:Insulinoma / Q000378:metabolism / Q000473:pathology* / Q000601:surgery; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D010190:Pancreatic Neoplasms / Q000378:metabolism / Q000473:pathology* / Q000601:surgery
D003094:Collagen; D005682:Gadolinium