Methylene blue to stain the bladder mucosa and monitor the course of bladder tumors.

In 12 patients with bladder tumors and in 15 undergoing multiple biopsies of grossly normal bladder mucosa to monitor the course of their bladder cancer, attempted staining of the mucosa with methylene blue failed to show any correlation with tumor histology. While histologically normal mucosal areas picked up the stain well, nonstaining areas were found to be dysplastic in 22% of the cases and showed endophytic masses in 2 patients. In 48% of patients excessive staining prevented adequate evaluation so that repeated endoscopy was necessary to confirm the absence of tumorous tissue. For these reasons, staining of the bladder mucosa with methylene blue is unsuited for the diagnosis of endophytic bladder tumors.