Crohn's-Associated Small Bowel Adenocarcinomas Exhibit Gastric Differentiation
Emma Whitcomb, Xiuli Liu, Shu-Yuan Xiao. University of Chicago, Chicago, IL; Cleveland Clinic, Cleveland, OH
Background: Long-term Crohn's enteritis increases the risk of small bowel adenocarcinoma (SBA), which, when compared to de novo SBA, usually occurs at a younger age, is frequently located in the ileum, and is more often poorly differentiated. In addition, we have observed that some cases of SBA in Crohn's disease exhibit gastric-type morphology, which may be related to pyloric gland metaplasia (PGM), a common finding in Crohn's disease. To investigate if this feature is unique to Crohn's SBA, a retrospective study (compared with non-Crohn's, de novo SBA) is performed.
Design: Cases of Crohn's-associated and de novo SBA were identified from the surgical pathology archives. H&E sections were examined for PGM. IHC was performed for CK20, CDX2, MUC2, CK7, MUC5AC and MUC6. Staining was scored on the invasive component as follows: 0 = entirely negative, 1+ = focally positive, and 2+ = diffusely positive. The two groups were then compared for their IHC expression frequencies.
Results: Seven cases of SBA in Crohn's disease were found and had adequate material for IHC evaluation and 7 de novo SBA cases were used as controls. Five of 7 Crohn's cases had PGM, which was absent in all de novo cases. By IHC, all de novo SBAs were positive for intestinal markers (CK20, CDX2, and MUC2) and 6 out of 7 were negative for gastric markers (CK7, MUC5AC, and MUC6). In contrast, all cases of Crohn's SBA were positive for a mixture of both intestinal and gastric markers. See Table 1.
|De Novo SBA (n = 7)||Crohns SBA (n = 7)|
|Intestinal Markers (% positive)|
|CK20||100% (n = 7)||86% (n = 6)|
|CDX2||100% (n = 7)||86% (n = 6)|
|MUC2||100% (n = 7)||71% (n = 5)|
|Gastric Markers (% positive)|
|CK7||14% (n = 1)||71% (n = 5)|
|MUC5AC||0% (n = 0)||71% (n = 5)|
|MUC6||0% (n = 0)||71% (n = 5)|