Radiographic, macroscopic and histological findings. A) Intravenous urography showing large bladder diverticulum, measuring 7 × 7 cm, with 3 cm stone-like component within (arrow). Diverticulum was compressing the bladder and dislocating right ureter towards the central line. B) Macroscopically, the bladder diverticulum contained grayish, solid tumor with gritty, firm centre that measured 3.5 cm in the largest diameter (arrow). C) The tumor was composed of anaplastic, oval to spindle cells, with prominent mitotic activity, partly rimmed with osteoid (HE, × 200). D) The central part of the tumor was composed of mineralized osteoid, deposited as irregular trabeculae with malignant osteocytes (HE, × 100).