smooth, round and well circumscribed on palpation. They are believed to be of mesothelial origin and are universally benign. Their sonographic appearance is that of a round-shaped, well-defined, homogeneous mass with echogenicity ranging from hypo- to iso- to hyperechoic. Fibrous pseudotumor Fibrous pseudotumors, also known as fibromas are thought to be reactive, nonneoplastic lesions. They can occur at any age, about 50% of fibromas are associated with hydrocele, and 30% are associated with a history of trauma or inflammation (Akbar et al., 2003). Although the exact cause of this tumor is not completely understood, it is generally believed that these lesions represent a benign reactive proliferation of inflammatory and fibrous tissue, in response to chronic irritation. Sonographic evaluation generally shows one or more solid nodules arising from the tunica vaginalis, epididymis, spermatic cord and tunica albuginea [Fig. 18]. A hydrocele is frequently present too. The nodules may appear hypoechoic or hyperechoic, depending on the amount of collagen or fibroblast present. Acoustic shadowing may occur in the absence of calcification due to the dense collagen component of this tumor. With color Doppler sonography, a small to moderate amount of vascularity may be seen [Fig. 19]. Inflammation Epididymitis and epididymo-orchitis Epididymitis and epididymo-orchitis are common causes of acute scrotal pain in adolescent boys and adults. At physical examination, they usually are palpable as tender and enlarged structures. Clinically, this disease can be differentiated from torsion of the spermatic cord by elevation of the testes above the pubic symphysis. If scrotal pain decreases, it is more likely to be due to epidiymitis rather than torsion (Prehn's sign). Most cases of epididymitis are secondary to sexually transmitted disease or retrograde bacteria infection from the urinary bladder. The infection usually begins in the epididymal tail and spreads to the epididymal body and head. Approximately 20% to 40% of cases are associated with orchitis due to direct spread of infection into the testis. At ultrasound, the findings of acute epididymitis include an enlarged hypoechoic or hyperechoic (presumably secondary to hemorrhage) epididymis [Fig. 20a]. Other signs of inflammation such as increased vascularity, reactive hydrocele, pyocele and scrotal wall thickening may also be present. Testicular involvement is confirmed by the presence of testicular enlargement and an inhomogeneous echotexture. Hypervascularity on color Doppler images [Fig. 20b] is a well-established diagnostic criterion and may be the only imaging finding of epididymo-orchitis in some men. Tuberculous epididymo-orchitis Although the genitourinary tract