| Background and purposeGastrointestinal stromal tumor (GIST) is the most common gastrointestinal mesenchymal tumor and primary epithelial tumor, which was proposed first in 1983 by Mazur and Clack. In 1998, kindblom discovered that gastrointestinal stromal tumor could express C-kit gene product, and then they speculated that C-kit gene was related with the occurrence of GIST which could distinguish the GIST and other gastrointestinal mesenchymal tumors. GIST is the most common mesenchymal tumor during the differentiation from mesenchymal cells to the ICC which can express C-kit gene product in immune phenotype. It can occur in the total length of the gastrointestinal tract, and some can be found in the abdominal cavity. In histology, the tumor usually constitutes of many spindle cells and epithelioid cells, and shows bundle-like or diffused arrangement pleomorphic cells sometimes. With the development of molecular biology of GIST, it has become a model of molecular targeted therapy from one of the least sensitive tumor to traditional chemotherapy and radiotherapy. And the biological behavior of GIST includes a broad spectrum from benign to highly malignant. So accurately determining benign and malignant GIST and assisting to select the appropriate clinical treatment is more important than the period lack of effective drug in the past. But How to determine the biological behavior of GIST becomes the tough problem of pathology. While multislice computed tomography (MSCT) has excellent density resolution. Therefore, the advantage of MSCT becomes more and more significant in determining morphological characteristics of GIST including biological behavior and structural features. This study investigated the diagnosis, differential diagnosis of GIST and the value of deciding the malignancy degree of MSCT. Thereby, it can improve our competence of diagnosis of gastrointestinal stromal tumor, and conduce to diagnosis and prognosis before surgery.Materials and MethodsForty-five patients with surgico-pathologically proved GIST,21 male and 24 female, were collected in The Chinese PLA General Hospital from May 2008 to August 2010. Of all the patients, there were multiple lesions in 2 cases, and single lesion in 43 cases. Clinical manifestations included melena(24.4%), abdominal pain(20%), abdominal discomfort(13.3%), abdominal mass(17.7%), asymptomatic (24.4%). All the cases were confirmed by surgery, pathology and immunohistochemistry, in which 24 cases were high-risk,9 cases mid-risk,13 cases low-risk, and extremely low-risk in 1 case. In the group,1 patient only undergone the MSCT plain scan of chest,2 patients took only one phase contrast scan of pelvic.42 patients received a plain CT scan followed by dual-phase enhanced scan using high pressure syringe by injecting iohexol (3.5ml/s). After injecting 90ml iohexol (300mg/ml), dual-phase enhanced was scaned with 5mm slice thickness,25-30s (arterial phase) and 65～70s (portal phase). Both plain and enhanced CT were reconstructed by 1.5mm slice thickness and 1.5mm slice gap. Combined with the clinical manifestations and pathological findings, we reviewed and summarize the performance on MSCT of all the selected cases. All datas were analyzed using SPSS 13.0. One-way analysis of variance and multinomial logistic regression were applied with clinical stage of tumor as the dependent variable and CT characteristics as independent variable (size of test, a=0.05).Results①In our series of forty-five cases,18 GIST involved Stomach (40%),16 cases small intestine (35.5%,6 cases duodenum,5 cases ileum,5 cases jejunum),5 cases colon (11.1%),5 cases retroperitoneal (11.1%),1 case chest(2.2%).②The lesions progress interior cavity in 7 cases, exterior and interior cavity in 11 cases, exterior cavity in 21 cases, retroperitoneal in 5 cases, and thoracic cavity 1 case.③Of the 47 lesions, the diameter of 26 ones exceed 5cm, the other lesions were equal or smaller than 5cm.④22 lesions showed round or round-like shape, and the other 25 lesions were irregular or lobulated shape. On the plain CT scan,26 lesions manifestated solid and well-defined mass with homogeneous density. And hemorrhage, cystic change and necrosis area could be found in 21 lesions. Besides, the ulcers were communicated with gastrointestinal cavity in 4 cases.⑤In the enhanced 44 lesions,16 cases showed uniform and solid enhancement with clear boundary,6 cases uneven and solid enhancement,4 cases orange-flap-like enhancement,2 cases uniform thick ring-like enhancement,11 cases unhomogeneous ring-like enhancement, and 5 cases irregular enhancement.⑥etastasis:Recurrence or metastasis occurred to 10 cases. The metasrasis included liver metastasis (8 cases), peritoneal metastasis (7 cases), spleen metastasis (3 cases), and adrenal metastasis(2 cases).⑦The result of One-way analysis of variance showed that the factors such as different size of tumors, cystic change, hemorrhage and calcification, and different kinds of enhancement of the tumor vs. clinical classification of the tumor had statistically significant, while other factors such as location, shape, growth pattern and degree of enhancement of the tumor vs. clinical classification of the tumor had no statistically significant. The results of multinomial logistic regression showed that in the condition of high-risk group as reference category, for the low-risk group, all of the factors such as size, enhancement kind and hemorrhage, cystic change, calcification of the tumor could affect the clinical classification of the tumor, while for the mid-risk group, the size and hemorrhage, cystic change, calcification of the tumor could affect the clinical classification of the tumor. Conclusions①Gastrointestinal stromal tumors usually occur in stomach, followed by small intestine. Tumors located in stomach and colon mostly progress interior cavity, and in small bowel usually grow inside and outside the cavity.②The intracavity uniform solid GIST with a diameter less than 5cm suggest they may be low risk.③The extracavity unhomogeneous enhanced tumors exceeding 5cm usually suggest they are high-risk GIST.④If abnormal blood vessels enhancement can be found in the tumor, it may be a suggestion for high-risk GIST.⑤GIST metastasizes primarily by hematogenous (liver and peritoneal for major), and lymph node metastasis is rare to see.⑥The size, hemorrhage, necrosis and cystic degeneration, and enhanced kind of the tumor are associated with the clinical classification. But the location, shape, growth pattern and degree of enhancement of the tumor are not correlated with clinical classification.⑦MSCT can clearly show the size, density, shape, growth mode, the relationship between adjacent structures, and distant metastases of GIST, moreover, it is useful to determine the malignant potential of the tumor. Therefore, MSCT is one non-invasive, simple and effective method for clinical preoperative diagnosis and evaluation of the tumor. |
PDF Full Text Request