Tubular ectasia of the rete testes may be mistaken for a intratesticular neoplasm. However, unlike a testicular neoplasm, tubular ectasia presents as variable sized cystic lesions in the region of the mediastinum testes with no associated soft-tissue abnormality and no flow or color flow on Doppler imaging. These classic findings distinguish this benign condition from a neoplasm. This abnormality is most often bilateral and often associated with epididymal obstruction secondary to inflammatory or traumatic lesions (i.e. vasectomy). (Rumack et al, Diagonostic Ultrasound p.802).