Testicular microlithiasis: is it a benign condition with malignant potential?

To review the findings of testicular ultrasonography (US) in patients referred for testicular symptoms including pain, swelling and infertility, and to determine the prevalence of testicular microlithiasis (TM) and ist relevance to the development of testicular cancer.

Records of 3,026 patients referred for testicular US between 1994 and 1999 were evaluated. The indications for testicular US diagnosis, management and relevant histological details were obtained from medical records. Patients with TM had an annual sonographic follow-up unless they had testicular cancer, in which case follow-up repeat US with clinical reviews was more frequent.

TM was found in 54 patients (1.77%; median age 34 years, range 12-83 years). The median follow-up was 36 months (range 12-18 months). Sixteen of these patients had testicular malignancy (30%). The remaining 38 patients had hydrocele and epididymal cysts (14), varicocele (7), epididymitis (2) and small testes (8), with 14 patients having no other pathology. One patient with a small testis developed a seminoma while under surveillance. Another patient with metastatic embryonal-cell carcinoma at initial diagnosis was found to have a seminoma 4 years following chemotherapy. The relative risk of testicular tumours in the presence of TM was 13.2 (confidence interval 8.3-21.5).

TM can no longer be regarded simply as a benign condition because of its association with testicular malignancy. In our series, 2 patients (5.2%) developed interval testicular cancers during follow-up US. There is no convincing evidence to suggest that TM might be premalignant. In rare instances of radiologically indeterminate cases, biopsy of the testis may be necessary.