Epidermoid cysts of the testicle: Sonographic and MR imaging features

OBJECTIVE. The purpose of this study is to analyze the appearance of testic ular epidermoid cysts on high-resolution sonography and MR imaging and corr elate imaging features with histopathologic findings. CONCLUSION. Intratesticular epidermoid cysts may show imaging features that correlate with their histopathologic findings. Concentric rings of alterna ting 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 o n color Doppler sonography and absence of contrast enhancement on MR imagin g is also consistent with the avascular nature of these lesions. The abilit y of preoperative imaging studies to suggest the diagnosis of epidermoid cy st may prompt a testis-sparing surgery instead of an orchiectomy.