Spontaneous Mucin-secreting Adenocarcinoma of the Ileum in a Male Crj: CD (SD) IGS Rat

Abstract

A small intestinal mucin-secreting adenocarcinoma was found in a 78-week-old male Crj: CD (SD) IGS rat. The neoplasm was present in a portion of the ileum as a white soft mass. Histologically, it consisted of pleomorphic mucin-producing glands, multiple cysts of various sizes, and a well-developed dense fibrous tissue stroma. Chronic inflammatory reaction and osseous metaplasia were observed in the stroma. Ultrastructurally, the microvilli of the epithelium at the luminal surface contained core filaments, and often appeared more stubby and sparse than usual.