MRI findings of pancreatic lymphoma and autoimmune pancreatitis: a comparative study.
OBJECTIVE
To clarify whether there are differences in MRI findings between pancreatic lymphomas and autoimmune pancreatitis (AIP).


METHODS
MRI of 8 patients with pancreatic lymphomas and 21 patients with AIP were retrospectively reviewed. For multifocal pancreatic lymphomas (n=2) and AIP (n=4), the largest 2 lesions were evaluated. Ten pancreatic lymphomas and 25 AIP were compared on three bases: the signal intensity on T2-weighted images, internal homogeneity, and presence or absence of capsule-like rim. In 8 lymphomas and 19 AIP, the enhancement pattern on dynamic MRI was compared, as well.


RESULTS
On T2-weighted images, pancreatic lymphomas comprised 5, 5 and 4 lesions with low (iso), slightly high, and moderately high intensity, respectively, while the numbers for AIP were 14, 10, and 1 (P<0.01). Nine of 10 (90%) lymphomas appeared homogenous, and 11 of 25 (44%) AIP were homogenous (P<0.05). A capsule-like rim was present in 9 of 25 (36%) AIP, but was not seen in lymphomas (P<0.05). On dynamic MRI, 18 of 19 (94.7%) AIP showed persistent (n=5) or delayed enhancement (n=13), and 6 of 8 (75%) lymphomas showed low intensity without delayed enhancement (P<0.001).


CONCLUSIONS
MRI findings for pancreatic lymphomas and AIP were significantly different, which may be helpful for the differential diagnosis of these two diseases.
Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan. Ishigamikousei@aol.com
Kousei
K
Ishigami
Tsuyoshi
T
Tajima
Akihiro
A
Nishie
Yasuhiro
Y
Ushijima
Nobuhiro
N
Fujita
Yoshiki
Y
Asayama
Daisuke
D
Kakihara
Hiroyuki
H
Irie
Tetsuhide
T
Ito
Hisato
H
Igarashi
Masafumi
M
Nakamura
Hiroshi
H
Honda
D000368:Aged; D000369:Aged, 80 and over; D001327:Autoimmune Diseases / Q000175:diagnosis*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008223:Lymphoma / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010190:Pancreatic Neoplasms / Q000175:diagnosis*; D050500:Pancreatitis, Chronic / Q000175:diagnosis*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity