A 69 year old man developed retention of urine 12 months before admission and had since suffered from urinary frequency and difficulty with micturition. Cystoscopy revealed a large prostate protruding into the bladder and a large dark bladder calculus. The specimen was removed by suprapubic cystostomy.
The specimen is a 'mulberry' calculus with a dark irregular nodular surface. This calculus is largely composed of calcium oxalate.