Epidermoid cysts of the testicle: sonographic and MR imaging features.

Objective: The purpose of this study is to analyze the appearance of testicular epidermoid cysts on high-resolution sonography and MR imaging and correlate imaging features with histopathologic findings.
Conclusion: Intratesticular epidermoid cysts may show imaging features that correlate with their histopathologic findings. Concentric rings of alternating hypo- and hyperechogenicity on sonography and alternating high and low signal intensity on MR imaging ("onion ring" appearance) correspond to the pathologic finding of multiple layers of keratin debris. Absence of flow on color Doppler sonography and absence of contrast enhancement on MR imaging is also consistent with the avascular nature of these lesions. The ability of preoperative imaging studies to suggest the diagnosis of epidermoid cyst may prompt a testis-sparing surgery instead of an orchiectomy.