Testicular microlithiasis: prevalence and tumor risk in a population referred for scrotal sonography

Considerable accrued evidence points to an association between testicular microlithiasis, intratubular germ cell neoplasia, and testicular tumor. This study assesses both the prevalence of testicular microlithiasis revealed on sonography in a referred population and the concurrent tumor risk.

Over a 32-month period (April 1996 through November 1998), 4892 scrotal sonographic examinations were performed in 4819 patients at four referral centers. All patients underwent high-resolution (7- to 10-MHz) imaging. Using a computerized word search (n = 4102; testicular microlithiasis, calcification, microliths, calcific foci, tumor, neoplasm, cancer, hyperecho, hypoecho, heterogen, and carcinoma) and manual retrieval (n = 790), cases of tumor, testicular microlithiasis (>5 microliths per sonogram), and testicular microlithiasis plus tumor were pulled and retrospectively reviewed. The presence and type of tumor were confirmed at histology after orchidectomy.

Fifty-four tumors were found among 4892 scrotal sonograms (28 seminomas, 14 teratomas, 8 mixed germ cell tumors, 2 Leydig cell tumors, and 2 non-Hodgkin's lymphomas). Testicular microlithiasis was present in 33 patients, giving a prevalence of 0.68%. Concurrent tumor and testicular microlithiasis were detected in seven patients, a relative risk of tumor in testicular microlithiasis was 21.6-fold (95% confidence limits: 10. 6-fold, 44.2-fold). In one patient with testicular microlithiasis, a previous orchidectomy for mixed germ cell tumor had been performed (not included in the relative risk calculation).

In a referred population of 4819 patients the prevalence of testicular microlithiasis was 0.68% and the relative risk of concurrent tumor was 21.6-fold. Sonographic surveillance of testicular microlithiasis cases for tumor is mandatory.