Radiological appearance of 'thimble' bladder is seen in the following condition:

Early tuberculosis of the bladder commences around the ureteric orifice or trigone, the earliest evidence being pallor of the mucosa due to submucosal oedema. Subsequently, tubercles may be seen and, in long standing cases, there is marked fibrosis and the capacity of the bladder is greatly reduced giving the radiological appearance of 'thimble bladder'. Ref: Bailey & Love's Sho Practice of Surgery 26E edited by Norman Williams, Christopher Bulstrode, P Ronan O'Connell, 2013, Page 1327-1328