Histopathological Changes in Kock Pouch

Abstract

To investigate whether tumour recurrence or histological changes occur in the Kock pouch, periodic endoscopy with biopsy of the pouch was performed in 15 patients 6 to 66 months after radical cystectomy and urinary diversion for invasive bladder cancer. Endoscopy was undertaken 1 to 4 times in each patient (a total of 37 times in all patients). During endoscopy, random biopsies were taken from the pouch wall, and from the afferent and the efferent nipples. The histological changes were graded as: (1) villous atrophy (grade 0 to 3, 0: nearly normal; 1: shortening, villi/crypt of Lieberkuhn [length] between 1.5 and 4.0; 2: moderate flattening, villi/crypt < 1.5; and 3: almost complete disappearance of villi); (2) fibrosis; and (3) chronic inflammation (grade 0 to 3, based on the amount of fibrous tissue and inflammatory cell infiltration in the lamina propria, respectively). There was no dysplasia or malignant tumour in the Kock pouch in any of the 15 patients. The histology of the ileum changed in terms of villous atrophy, fibrosis and chronic inflammation in the lamina propria and thickening of the muscularis mucosa. The same grade of villous atrophy of the pouch wall, the afferent and the efferent nipples was only found in 3 patients. More fibrosis and less chronic inflammation in the lamina propria were found at the efferent nipple than at the afferent nipple or pouch wall in 8 patients and 5 patients, respectively. Thickening of the muscularis mucosa was found in 13 of 15 patients (86.7%). In conclusion, there was no dysplasia or recurrent tumour in the Kock pouch in patients who were followed for up to 66 months. Various grades of histological changes of the ileum in terms of villous atrophy, fibrosis and chronic inflammation of the lamina propria, and thickening of the muscularis mucosa were found in the pouch wall, and in the afferent and efferent nipples. More fibrosis and less chronic inflammation were commonly observed at the efferent nipple than at the afferent nipple or pouch wall. The degree of histological changes varied even among patients followed over the same period after operation. The time to progression of villous atrophy also varied. The histological changes in some patients were dissimilar even at the same site of the Kock pouch.