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.
Ishigami
Kousei
K
Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan. Ishigamikousei@aol.com
Tajima
Tsuyoshi
T
Nishie
Akihiro
A
Ushijima
Yasuhiro
Y
Fujita
Nobuhiro
N
Asayama
Yoshiki
Y
Kakihara
Daisuke
D
Irie
Hiroyuki
H
Ito
Tetsuhide
T
Igarashi
Hisato
H
Nakamura
Masafumi
M
Honda
Hiroshi
H
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