Mucosal thickening of 0.5 cm in the bladder triangle is commonly caused by adenoid cystitis or bladder tumors. 1. Adenoid cystitis: Adenoid cystitis is a non-neoplastic bladder mucosal epithelial hyperplasia, which is considered to be a precancerous lesion because of both hyperplasia and metaplasia. It can be diagnosed by symptoms combined with cystoscopy. 2. Bladder tumor: Thickening of mucosa in the bladder triangle is also commonly seen in the tumor at the mucosa. Usually, patients try to eat less fried food and stimulating food, and eat more fruits and vegetables, which is more conducive to the improvement of the condition. There may be other reasons for the thickening of the mucous membrane in the bladder triangle, if the condition worsens or sudden discomfort, you need to go to the hospital in time and follow the doctor’s instructions for treatment.