1、读书报告会2017,Differentiation of large (5 cm) gastrointestinal stromal tumors frombenign 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。,C
2、ase,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
3、. 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
4、 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
5、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-e
6、pithelial 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
7、 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 ye
8、ars).,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
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
10、 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 pr
11、oximal 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
12、 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 wel
13、l-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
14、 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 ca
15、tegorized 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 subep
16、ithelial 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 lef
17、t 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.,Results,Page 17,Results,Fig. 5. A 61-yea
18、r old man with gastric schwannoma. (A) On portal phase CT scan, an 11 cm large heterogeneous iso-attenuating mass (*) is seen at the greater curvature side of the gastric mid body. There is no necrosis within the tumor or surface ulcerations.(B) Serial CT images show multiple enlarged and enhancing
19、lymph nodes (arrowheads) at the perigastric and paraaortic areas. After wedge resection, the lesion was confirmed as a gastric schwannoma (not shown). Reactive hyperplasia was noted at four lymph nodes in the resected specimen (not shown).,Page 18,Fig. 6. A 49-year old man with gastric leiomyoma. (A
20、) Arterial and portal phase CT images demonstrate a 6 cm homo-geneous and low-attenuating subepithelial mass (*) involving the gastric cardia and gastro-esophageal junction (arrows). The lesion shows an endophytic growth pattern. There is no intratumoral necrosis, calcification, and surface ulcerati
21、ons. No enlarged lymph nodes were observed. Both radiologists diagnostic confidence was improved from 2 (probably non-GIST) to 1 (definitely non-GIST) during the two successive review sessions. (B) Gross specimen obtained after wedge resection shows an elongated subepithelial tumor (arrows). On a cu
22、t section (right lower corner) of the tumor, the tumor has a gray to white, whirling cut surface without foci of necrosis or hemorrhage.,Results,Discussion,In this study, none of the gastric schwannomas and leiom-yomas except one schwannoma showed intra-tumoral necrosis. gastric leiomyomas seldom ac
23、company with intra-tumoral necrosis. This should not be surprising considering the relatively slow speed of tumor growth in benign tumors which is typically on par with that of neovascularization.,Page 19,Discussion,Conversely, in malignant tumors such as GIST, the speed of tumor growth often outstr
24、ips that of neovascularization leading to central necrosis. Even though the presence of necrosis at the center of the tumor is a well-known imaging feature of GISTs, particularly large GISTs 57, the absence of necrosis in gastric schwannomas on imaging studies has not been emphasized in previous stu
25、dies 10,11.,Page 20,Discussion,We believe that the results of this study suggest and con-firm that the presence of necrosis is a differentiating CT feature of GIST which has already been well-established in the pathologic field.,Page 21,Discussion,In other words, the presence of enlarged lymph nodes
26、 is a highly specific CT finding for gastric schwannoma according to our study results. In our study, 75% (12/16) of large schwannomas had enlarged lymph nodes whereas only 5.1% (5/99) of large GISTs had lymphadenopathy.,Page 22,Discussion,Our study demonstrated that gastric leiomyomas were exclusiv
27、ely located at the cardia of the stomach.,Page 23,Conclusion,In conclusion, heterogeneous enhancement and presence of necrosis are CT findings highly suggestive of large GISTs in differentiation from large gastric schwannomas or leiomyomas. Inaddition, the presence of enlarged lymph nodes is a specific CT feature of gastric schwannoma and the cardial location is a highly sensitive finding of gastric leiomyoma.,Page 24,
