Cystic dysplasia of the testis (CDT) is a rare, benign and congenital lesion causing scrotal mass in pediatric population that can mimic testicular cancer. This lesion consists of cystic dilation of the rete testis and it is frequently associated with renal or genitourinary tract anomalies as renal agenesis and multicystic dysplasia of the kidney. This frequent presentation suggests that testicular cystic dysplasia is associated with a defect of the metamesonephric system in particular with a defect in the connection between the efferent ducts derived from the mesonephros and the rete testis tubules derived from the gonadoblastoma. The role of ultrasound is of primary importance for clinical diagnosis and follow-up of untreated forms. The sonographic appearance of CDT consists of multiple cysts in the mediastinum testis. The cysts range in size from microscopic to several millimetres and may involve the whole testicular parenchyma or have a focal aspect. If the cysts are tiny, the ultrasound must be able to distinguish between CDT and testicular microlithiasis, a potential premalignant condition. Today it is possible thanks to high frequency 7.5 to 10 mHz probes. In the past orchiectomy has been considered as the treatment of the choice for CDT. Today, non operative management of CDT represents an effective alternative option in these patients and the primary benefit of this approach is the preservation of endocrine function and spermiogenic activity. However, the natural history of untreated CDT and its effect on normal testicular tissue are still unknown, therefore long-term follow-up is recommended.