读书报告会2017,Differentiation of large (5 cm) gastrointestinal stromal tumors from benign subepithelial tumors in the stomach,CONTENTS,目录,1,Introduction,2,Materials and methods,3,Results,4,Discussion,5,Case,6,Conclusion,Page 3,Case,患者：女性，61岁 主诉：发现左上腹肿块5年 专科体查：腹部平软，全腹无压痛及腹肌紧张，剑突下偏右可触及一肿块，大小约46cm,边缘清楚，无压痛。,Case,Page 4,Page 5,Case,Page 6,Case,免疫组化结果显示:Bcl-2(+),CD34(+),Calretinin( ),EMA(),Ki-67(+约0.9%), S-100(),SMA( ), CD117(+),DOG-1(+),CD99(+) 间质瘤,Page 7,Introduction,Like many other organs, the stomach is not only the origin of epithelial tumors and lymphomas, but also a wide range of mesenchymal tumors. Approximately 3% of all gastric tumors belong to the latter group . Gastric mesenchymal tumors can be divided into four main categories; true smooth muscle tumors neurogenic tumors, fibroblastic tumors, and gas-trointestinal stromal tumors(GISTs).,Gastric mesenchymal tumors typically manifest as a sub-epithelial lesion on both imaging and pathologic exam-inations. Except in very rare leiomyosarcomas , all gastric mesenchymal tumors other than GISTs are almost always benign. GISTs, on the other hand, even when they are small, are potentially malignant . Therefore, accurate differentiation of GISTs from other benign subepithelial tumors is crucial for planning management options,Page 8,Introduction,Introduction,In this study, we attempted to determine whether there are characteristic CT features which may help differentiate GISTs from non-GISTs in patients with large (5 cm) gastric sub-epithelial tumors. Additionally, we assessed whether radio-logists performance in differentiation can be improved with knowledge of these CT criteria.,Page 9,Page 10,Materials and methods,Materials and methods,Finally, 120 patients with 5 cm gastric subepithelial tumors were enrolled in our study: 99 patients with GIST (57 men, 42 women; mean age, 60.412.9 (standard deviation (SD) years; range, 2585 years), 16 patients with sch-wannoma (7 men, 9 women; mean age, 58.9 12.4 (SD) years; range, 3783 years), and 5 patients with leiomyoma (3 men, 2 women; mean age, 42.413.2 (SD) years; range, 2763 years).,Page 11,Results,Page 12,Clinical and pathologic features of 120 patients with large (5 cm) gastric subepithelial tumors.,Results,Page 13,Page 14,Fig. 2. A 57-year old man with gastric gastrointestinal stromal tumor (GIST). (A) Arterial (left) and portal (right) phase CT images demonstrate a 9 cm huge heterogeneous,low-attenuating subepithelial mass involving the greater cur-vature side of the gastric upper thirds, showing a mixed endo- and exophytic growth pattern. There are irregular necrosis and air-density (arrows) within the mass. A surface ulceration (arrowhead) is also noted at the endoluminal surface of the mass.Enlarged lymph nodes were not observed on CT. Both radiologists correctly interpreted this lesion as a GIST during the two review sessions and their diagnostic confidence was improved from 4 (probably GIST) to 5 (definitely GIST). (B) Gross specimen obtained after proximal gastrectomy shows a 9 cm huge subepithelial tumor (arrows) with surface ulcerations (arrowheads). On a cut section (right lower corner) of the tumor, the tumor has a gray to white cut surface with foci of necrosis or hemorrhage.,Results,Page 15,Results,Fig. 3. A 55-year old woman with gastric gastrointestinal stromal tumor (GIST).(A) On portal phase CT, a 6 cm heterogeneous, low-attenuating subepithelial mass (arrows) is seen at the posterior wall of the gastric upper thirds. The lesion shows a mixed growth pattern. There is a low attenuating necrotic portion (*) within the tumor. A well-enhancing enlarged lymph node (arrowhead) is also noted at the perigastric area. Two radiologists interpreted this lesion as GIST during the two interpretation sessions and the con-fidence level was improved by one reviewer from 3 (possibly GIST) to 5 (definitely GIST). (B) Gastric wedge resection specimen shows a 6 cm subepithelial mass (arrows) with surface ulcerations (arrowheads). Microscopic examination confirmed the diagnosis of a gastrointestinal stromal tumor (not shown). There was necrosis and hemorrhage in the tumor and its mitotic count was 2/50 HPFs. Therefore, this lesion was categorized as having an intermediate risk of aggressive behavior. There was no malignant focus in the four resected lymph nodes (not shown). HPF, high-power field.,Page 16,Fig. 4. A 39-year old woman with gastric schwannoma. (A, B) On portal phase CT images, an 8 cm homogeneous, low-attenuating subepithelial mass (*) is seen at the lesser curvature side of the gastric mid-body, showing a mixed endo- and exophytic growth pattern. A small surface ulceration (arrow) was noted at the endoluminal surface of the lesion. There are several enlarged and well-enhancing lymph nodes (arrowheads) at the left gastric and perigastric areas. The tumor was interpreted as gastric GIST by both reviewers (confidence level: 4, probably GIST) at the first review session, but was recorded as schwannoma by both reviewers (confidence level: 1) at the second review session.,