Multimodality imaging of paratesticular neoplasms and their rare mimics.

Extratesticular neoplasms are rare but clinically significant lesions that affect patients of all ages. These neoplasms are generally asymptomatic but may have potentially life-threatening sequelae. Lipoma is the most common primary benign paratesticular neoplasm and the most common tumor of the spermatic cord. Adenomatoid tumor is the most common tumor of the epididymis, followed by leiomyoma. In adult patients, it is imperative to consider sarcomas in the differential diagnosis of all solid tumors of the scrotum. The most common sarcomatous tumors in pediatric patients are embryonal sarcoma and rhabdomyosarcoma. Metastases, particularly from testicular, prostatic, renal, and gastrointestinal primary malignancies, can also occur. Mimics of paratesticular neoplasms including polyorchidism and splenogonadal fusion are rare but must also be considered for optimal management. Ultrasonography (US) is currently the imaging modality of choice. However, US findings are often variable and nonspecific and do not usually allow definitive characterization. Specific computed tomographic and magnetic resonance imaging findings with respect to tumor location, morphologic features, and tissue characteristics can aid in the evaluation of paratesticular neoplasms and help narrow the differential diagnosis. Copyright RSNA, 2003