A prostatic calculus (stone) is frequently asymptomatic and is often associated with benign prostatic hypertrophy. Nevertheless, in some cases, hypertrophy and stones can cause lower urinary tract symptoms. Surgical removal of the stones is either by transurethral procedures, sometimes combined with ultrasound observation, or by suprapubic extraction; however, surgery is not usually necessary.
Prostatic calculus occurs frequently in older men and is often discovered incidentally, as it is asymptomatic in most cases. Endogenous stones are formed by deposition of inorganic salts, mainly calcium phosphate, on the corpora amylacea of the prostatic acini. Corpora amylacea are small, round bodies made of lipids and proteins derived from epithelial cells . Secondary calculi are formed from urine components   in the prostatic duct . Most stones are between 1 and 4 mm in size, and are usually multiple.
The proportion of men with prostatic calculi has varied widely in different studies . This may be because of differences in the subjects selected for the studies, and because of the different methods and criteria used to detect the stones . Among the risk factors, age is the most cited  ; older age is associated with more numerous and larger stones.
Prostatic calculi manifest with lower urinary tract symptoms, which include dysuria, rarely hematuria, pelvic pain, obstruction and infection. Although there is an association between prostatic calculi and urinary tract symptoms, the relationship is not quite clear, because the presence of stones is associated with other conditions that can also cause urinary tract problems. Men with chronic prostatitis were found to have a higher burden of calculi than the ones without prostatitis . Another investigation found that among patients with chronic pelvic pain syndrome those who had prostatic stones harbored more bacteria in the prostatic fluid and showed a stronger indication of inflammation than those who did not have stones . Larger calculi were more often found in patients with chronic prostatitis or chronic pelvic pain syndrome than small calculi . With the frequent coexistence of the calculi and other conditions, it is not clear whether the stones can, in themselves, result in lower urinary tract symptoms. With the aim of answering this question, a multivariate analysis of both subjective and objective symptoms in relation to calculi, age, and prostate volume, concluded that the stones were not independent determinants of the symptoms  although patients with calculi were afflicted with more severe symptoms than those without. Calculi may contribute to urinary tract infection by blocking drainage from the prostate, thereby providing an environment for recurrent infections .
Prostatic stones are often discovered in older men incidentally when imaging studies are performed for other reasons. The stones can also be palpated during a digital rectal examination.
Tests for associated lower urinary tract symptoms include the Meares-Stamey four-glass test to check for bacteria and white blood cells in urine and expressed prostatic secretions . Prostatic stones are measured with the transrectal ultrasound scan. The calculi appear as hyperechoic areas with shadows . The stones can be identified on radiographs and computerized tomography scans, as well on samples from transurethral resection of the prostate.