Ectopic pancreas: CT findings with emphasis on differentiation from small gastrointestinal stromal tumor and leiomyoma.
OBJECTIVE
To describe the computed tomographic (CT) findings of ectopic pancreas and to identify the features that differentiate it from other similarly manifesting gastric submucosal tumors such as gastrointestinal stromal tumor (GIST) and leiomyoma, which are the most common gastrointestinal submucosal tumors.


METHODS
This retrospective study was approved by the institutional review board and did not require informed consent. CT images of pathologically proved ectopic pancreases (n = 14), GISTs (n = 33), and leiomyomas (n = 7) in the stomach and duodenum were retrospectively reviewed. Analysis of the CT findings included evaluation of the location, contour, growth pattern, border, enhancement pattern, and enhancement grade of the tumor, as well as the presence of surface dimpling, prominent enhancement of overlying mucosa, and low intralesional attenuation. The attenuation of each lesion, the long diameter (LD), the short diameter (SD), and the LD/SD ratio were measured. Among these findings, statistically significant variables were determined by using the chi(2) test (to compare the categoric variables), the Student t test (for quantitative analysis), and the receiver operating characteristic curve (to determine the optimal cutoff of the LD/SD ratio).


RESULTS
The typical location (prepyloric antrum and duodenum), endoluminal growth pattern, ill-defined border, prominent enhancement of overlying mucosa, and an LD/SD ratio of greater than 1.4 were found to be significant for differentiating ectopic pancreas from other tumors (P < .05 for each finding). When at least two of these five criteria were used in combination, the sensitivity and specificity for diagnosing ectopic pancreas were 100% (14 of 14) and 82.5% (33 of 40), respectively. When four of these criteria were used, a sensitivity of 42.9% and a specificity of 100% were achieved.


CONCLUSIONS
By using specific CT criteria, ectopic pancreas can be differentiated from small GIST or leiomyoma with a high degree of accuracy.
Kim
Ji Young
JY
Department of Radiology, Institute of Radiation Medicine, Seoul National University College of Medicine, Seoul National University Hospital, 28 Yeongon-dong, Jongno-gu, Seoul 110-744, Korea.
Lee
Jeong Min
JM
Kim
Kyung Won
KW
Park
Hee Sun
HS
Choi
Jin Young
JY
Kim
Se Hyung
SH
Kim
Min A
MA
Lee
Jae Young
JY
Han
Joon Koo
JK
Choi
Byung Ihn
BI
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002828:Choristoma / Q000000981:diagnostic imaging*; D003937:Diagnosis, Differential; D005260:Female; D046152:Gastrointestinal Stromal Tumors / Q000000981:diagnostic imaging*; D006801:Humans; D007889:Leiomyoma / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D010179:Pancreas; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013272:Stomach Diseases / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014594:Uterine Neoplasms / Q000000981:diagnostic imaging*