Background: To systematically evaluate the incidence characteristics of testicular microlithiasis (TM) in children and its association with primary testicular tumors (PTT).
Methods: A systematic review and meta-analysis were conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) statement. A priori protocol was registered in the PROSPERO database (CRD42018111119), and a literature search of all relevant studies published until February 2019 was performed. Prospective, retrospective cohort, or cross-sectional studies containing ultrasonography (US) data on the incidence of TM or the association between TM and PTT were eligible for inclusion.
Results: Of the 102 identified articles, 18 studies involving 58,195 children were included in the final analysis. The overall incidence of TM in children with additional risk factors for PTT was 2.7%. In children, the proportion of left TM in unilateral cases was 55.7%, the frequency of bilateral TM was 69.0%, and proportion of classic TM was 71.8% [95% confidence interval (CI) 62.4-81.1%, P = 0.0, I2 = 0.0%]. About 93.5% of TM remained unchanged, and newly detected PTT rate was very low (4/296) during follow-up. The overall risk ratio of TM in children with a concurrent diagnosis of PTT was 15.46 (95% CI 6.93-34.47, P < 0.00001).
Conclusions: The incidence of TM in children is highly variable. Nonetheless, TM is usually bilateral, of the classic type, and remains stable or unchanged at follow-up. Pediatric patients with TM and contributing factors for PTT have an increased risk for PTT; however, there is no evidence to support mandatory US surveillance of children with TM.
Keywords: Children; Incidence; Primary testicular tumors; Testicular microlithiasis.