胃肠间质瘤的分期和分级尚未明确。我们发现了12项形态学指标，包括肉眼播散指标（肝转移、腹腔播散）、镜下播散（淋巴结转移、血管浸润、脂肪浸润、黏膜浸润和神经浸润）以及原位的形态学指标（肌层浸润、核分裂像≥10个/50HPF）、肿瘤性坏死、古钱币样结构以及较弥漫显著异型等。具有任意一项指标者可划为恶性胃肠间质瘤（胃肠间质肉瘤），依据有无肉眼播散分为临床II期和I期，临床I期胃肠间质肉瘤者，具有1～2项形态学指标划为低度恶性、3～4项划为中度恶性、4～5项划为高度恶性。这种分期分级方法与胃肠间质瘤生物学行为相关。

Malignant degree of gastrointestinal stromal tumor and the impact on biological behavior        HOU Ying-yong*, ZHU Xiong-zeng. *Department of Pathology，Zhongshan Hospital of Fudan University, Shanghai 200032, China
Corresponding author: HOU Ying-yong, E-mail: houyingyong@hotmail.com
Abstract    Tumor stage and grade for gastrointestinal stromal tumors are undetermined. Twelve 12 clinical and pathological parameters were identified. The parameters are classified into two gross spread parameters including liver metastasis and peritoneal dissemination, five microscopic spread parameters including lymph node metastasis, vascular, fat, nerve and mucosal infiltration, and five histological parameters including mitotic count > or =10 per 50 high-power fields, muscularis propria infiltration, coagulative necrosis, Chinese-ancient-coin-like pattern and severe nuclear atypia. Malignant gastrointestinal stromal tumors which presented at least one of  above-mentioned parameters can be divided into clinical stage I and II based on the absence and presence of gross spread respectively. The degree of malignancy of patients in clinical stage I could be graded according to the number of predictive parameters of malignancy. Patients in clinical stage II are of the highest degree of malignancy regardless of the number of parameters. It finds that the clinical stage and grade are associated with biologic behavior strongly.