Mixed adenocarcinoma/carcinoid tumour of large bowel in a patient with Crohn's disease.

A 50 year old woman with a 20 year history of Crohn's disease underwent laparotomy which revealed extensive disease in the small and large bowel, and this was resected. Gross examination of the resected bowel showed features of Crohn's disease as well as a polypoid tumour in the caecum. Histopathological examination of the tumour showed it to be an infiltrating mixed adenocarcinoma/carcinoid tumour arising in a tubulovillous adenoma. Random sampling of the rest of the bowel affected by Crohn's disease also showed a focus of dysplasia and adenomatous change. It is suggested that Crohn's disease may have played a part in the pathogenesis of the tumour.