Sonographic features of duodenal lipomas in eight clinicopathologically diagnosed patients.

Aim: To investigate the sonographic features and diagnostic value of endoscopic ultrasonography (EUS) for duodenal lipomas (DLs).

Methods: A total of eight consecutive patients with DL diagnosed pathologically were included in the study. One EUS expert reviewed the ultrasonic images for all lesions, including the original layer of the duodenal wall, the echo intensity and the echo homogeneity. The size of the lesions and the perifocal structures were also investigated. The diagnosis by EUS was compared with the histological results.

Results: Using routine endoscopy, only one case was correctly diagnosed as DL. Four cases were classified as submucosal tumors, and three cases were mistaken for stromal tumors. All tumors appeared as round or oval intensive hyperechoic lesions with distinct anterior borders that originated from the submucosal layer on EUS. Tumors ranged from 8 to 36 mm in size, with an average size of 16 mm. Homogeneous echogenicity was seen in all cases except one that had a tubular structure inside the tumor. Echo attenuation was observed only in the area behind the tumors in five cases, and it was observed both inside and behind the tumors in three cases in which the posterior border was obscure or invisible. Seven (87.5%) cases were correctly diagnosed as DL, and one (12.5%) was mistaken as Brunner's gland adenoma by EUS. Pathologically, all tumors originated from the submucosal layer and consisted of mature fat cells without heteromorphism. Among the fat cells, there was a small amount of thick-wall vessels infiltrating the lymphocytes, and abundant fibrous connective tissues.

Conclusion: On EUS, DL is featured as an intensive homogeneous hyperechoic submucosal lesion with marked echo attenuation and without involvement of the mucosa.