Flow cytometry analysis of proliferative lesions at the gastrocystoplasty anastomosis

Proliferative epithelial metaplasia that develops in the anastomotic line after gastrocystoplasty has unknown malignant potential. Flow cytometry analysis of cell cycle profiles is used to predict the neoplastic progression of metaplastic lesions in other proliferative epithelium. We used this technique to evaluate transitional cell metaplasia in rat gastrocystoplasty specimens.

A total of 50 prepubescent female Long-Evans rats were randomly assigned to an experimental group (gastrocystoplasty) or a control group (sham operation). At 21 to 27 months (mean 24.9) after operation 12 rats per group survived to sacrifice. Metaplastic lesions were microdissected to yield a minimum of 10(4) cells for DNA flow cytometry and cell cycle analysis. Transitional cell epithelium from sham specimens and gastric epithelium from experimental animals served as controls.

Transitional cell hyperplasia and metaplasia with cyst formation were found in the anastomotic line in all 12 augmented bladders (100%). No proliferative lesions developed in control animals. No nuclear pleomorphism or mitotic changes were identified on routine histological examination. The epithelial cell turnover rate was 10 times higher in the gastrocystoplasty junctional zone than in control bladders (mean 2.2% versus 0.1% S phase) but lower than in native stomach epithelium (mean 3.3% S phase). Of 12 experimental specimens 1 showed near diploid DNA aneuploidy. No DNA abnormalities were detected in control bladder or stomach specimens.

In this animal model histologically benign appearing proliferative lesions that develop in the anastomotic zone after long-term gastrocystoplasty harbor cell cycle and DNA ploidy abnormalities.