A Clinicopathological Study of Primary Small Intestinal Cancer with Emphasis on Cellular Characteristics

We examined the clinicopathological profiles and cellular characteristics of 10 cases of surgically resected primary small intestinal cancers (excluding duodenal cancers). Histological examination revealed nine adenocarcinomas and one sarcomatoid carcinoma. Invasion depth was subserosal in five cases, serosal in four cases and to the adjacent transverse colon in the remaining case. Metastasis was present in lymph node in seven cases, in distant organs in six, and in the peritoneum in seven cases. Of the 10 cases, 7 underwent postoperative chemotherapy, and 6 of the eight traceable patients died from the disease (mean period of survival: 386 days). Histomorphologically, eight of nine adenocarcinomas showed an intestinal phenotype (unclassifiable in the other) in the upper layer, while in the lower layer, there showed an intestinal phenotype and five a non-intestinal phenotyp. Immunohistochemistry revealed a mean positive rate in the upper/lower layers as follows: 93%/86% and 38%/29% by intestinal markers CDX2 and MUC2; 19%/28% and 13%/32% by pancreatobiliary markers CK7 and MUC1; and 4%/19% and 2%/9% by gastric markers MUC5AC and MUC6, respectively. Thus, the intestinal phenotype predominated in almost all small intestinal cancer in this study, although some showed a transformation to non-intestinal or hybrid phenotypes with tumor progression. Flexible management for the diversity and transformation of cellular characteristics is therefore recommended treating and diagnosing small intestinal cancers