| [ Summary ] |
In order to grasp the characteristic features of metastatic tumors of the small intestine, 73,134 autopsy cases were registered in a nationwide pathologic autopsy database in Japan over the past 13 years and 22 surgical specimens examined at our institute were studied from the standpoint of clinicopathology. The autopsy series revealed that metastasis to the small intestine occurred most frequently in the gastrointestinal tract and the incidence of metastasis to the small intestine was 8.53 %. The primary site of malignant tumors that has with a high incidence of metastasis to the small intestine was mostly neighboring organs or intra-abdominal organs. Therefore, most metastatic tumors of the small intestine in autopsy case seems to be attributable to direct invasion or disseminated metastasis from a neighboring organ, reflecting the end stage of malignant tumor of intra-abdominal organs. On the other hand, examination of the 22 surgical cases revealed that primary lesions were located in the colon in 7 cases, in the stomach, rectum and lung in 4 cases each, in the bile duct and gallbladder in 2 cases, and in the ovaries in 1 case. According to the classification of pathways of spreading and metastasis of tumors, the cases were classified as been disseminated metastasis (11 cases), direct invasion (9 cases), and distant metastasis (2 cases). The most common histological cell type of a primary tumor was adenocarcinoma, differentiated type. The most common microscopic features of the metastatic tumors resulting from direct invasion from a neighboring organ or intraperitoneal seeding were the proliferation of carcinoma cells, mainly in the deeper portion of the muscularis propria, accompanied by the stromal fibrosis (desmoplastic reaction) in the submucosa and subserosal layer. In conclusion, to comprehend the characteristic clinicopathological features of tumors of the small intestine it is necessary to detect whether or not they are metastatic tumors, and also to locate the primary site of the metastasis. Discovery of this in the early stages of disease helps in formulating correct the choice of a precise and effective therapies. |