first two decades, it may develop anywhere in the body, and 4% occur in the paratesticular region which carries a better outcome than lesions elsewhere in the genitourinary tract. Clinically, the patient usually presents with non-specific complaints of a unilateral, painless intrascrotal swelling not associated with fever. Transillumination test is positive when a hydrocele is present, often resulting in a misdiagnosis of epididymitis, which is more commonly associated with hydrocele. The ultrasound findings of paratesticular rhabdomyosarcoma are variable. It usually presents as an echo-poor mass [Fig. 11a] with or without hydrocele. With color Doppler sonography these tumors are generally hypervascular. Mesothelioma Malignant mesothelioma is an uncommon tumor arising in body cavities lined by mesothelium. The majority of these tumors are found in the pleura, peritoneum and less frequently pericardium. As the tunica vaginalis is a layer of reflected peritoneum, mesothelioma can occur in the scrotal sac. Although trauma, herniorrhaphy and long term hydrocele have been considered as the predisposing factors for development of malignant mesothelioma, the only well established risk factor is asbestos exposure. Patients with malignant mesothelioma of the tunica vaginalis frequently have a progressively enlarging hydrocele and less frequently a scrotal mass, rapid re-accumulation of fluid after aspiration raises the suggestion of malignancy. The reported ultrasound features of mesothelioma of the tunica vaginalis testis are variable. Hydrocele, either simple or complex is present and may be associated with: multiple extratesticular papillary projections of mixed echogenicity; multiple extratesticular nodular masses of increased echogenicity; focal irregular thickening of the tunica vaginalis testis; (4) a simple hydrocele as the only finding and A single hypoechoic mass located in the epididymal head. With color Doppler sonography, mesothelioma is hypovascular [Fig. 12]. Leiomyoma Leiomyomas are benign neoplasms that may arise from any structure or organ containing smooth muscle. The majority of genitourinary leiomyomas are found in the renal capsule, but this tumor has also been reported in the epididymis, spermatic cord, and tunica albuginea. Scrotal leiomyomas have been reported in patients from the fourth to ninth decades of life with most presenting during the fifth decade. These tumors are generally slow growth and asymptomatic. The sonographic features of leiomyomas have been reported as solid hypoechoic or heterogeneous masses that may or may not contain shadowing calcification. Other findings include whorl shaped configuration [Fig. 13a] of the nodule and multiple, narrow areas of shadowing not cast by calcifications [Fig. 13b], but corresponding to transition