lobulated masses. lymphoma fig. 7. lymphoma. lymphoma in a 61-year-old man. longitudinal sonography shows an irregular hypoechoic lesion occupied nearly the whole testis. fig. 8. primary lymphoma. longitudinal sonography of a 64-year-old man shows a lymphoma mimicking a germ cell tumor. clinically lymphoma can manifest in one of three ways: as the primary site of involvement, or as a secondary tumor such as the initial manifestation of clinically occult disease or recurrent disease. although lymphomas constitute 5% of testicular tumors and are almost exclusively diffuse non-hodgkin b-cell tumors, only less than 1% of non-hodgkin lymphomas involve the testis. patients with testicular lymphoma are usually old aged around 60 years of age, present with painless testicular enlargement and less commonly with other systemic symptoms such as weight loss, anorexia, fever and weakness. bilateral testicle involvements are common and occur in 8.5% to 18% of cases. at sonography, most lymphomas are homogeneous and diffusely replace the testis . however focal hypoechoic lesions can occur, hemorrhage and necrosis are rare. at times, the sonographic appearance of lymphoma is indistinguishable from that of the germ cell tumors , then the patient's age at presentation, symptoms, and medical history, as well as multiplicity and bilaterality of the lesions, are all important factors in making the appropriate diagnosis. leukemia primary leukemia of the testis is rare. however, due to the presence of blood-testis barrier, chemotherapeutic agents are unable to reach the testis, hence in boys with acute lymphoblastic leukemia, testicular involvement is reported in 5% to 10% of patients, with the majority found during clinical remission. the sonographic appearance of leukemia of the testis can be quite varied, as the tumors may be unilateral or bilateral, diffuse or focal, hypoechoic or hyperechoic. these findings are usually indistinguishable from that of the lymphoma . fig. 9. leukemia. diffuse hypoechoic infiltrative lesions are seen involving the whole testis, indistinguishable from that of the lymphoma. epidermoid cyst fig. 10. epidermoid cyst. onion peel appearances of the tumor together with absence of vascular flow are typical findings of epidermoid cyst. epidermoid cysts, also known as keratocysts, are benign epithelial tumors which usually occur in the second to fourth decades and accounts for only 1–2% of all intratesticular tumors. as these tumors have a benign biological behavior and with no malignant potential, preoperative recognition of this tumor is important as this will lead to testicle preserving surgery (enucleation) rather than unnecessary orchiectomy. clinically, epidermoid cyst cannot be differentiated from other testicular tumors, typically presenting as a non-tender, palpable, solitary intratesticular mass. tumor markers such as serum beta-human chorionic gonadotropin and alpha-feto protein are negative. the ultrasound patterns of epidermoid cysts are variable and include: a mass with a target appearance, i.e. a central hypoechoic area surrounded by an echolucent rim; an echogenic mass with dense acoustic shadowing due to calcification; a well-circumscribed mass with a hyperechoic rim; mixed pattern having heterogeneous echotexture and poor-defined contour and an onion peel appearance consisting of alternating rings of hyperechogenicities and hypoechogenicities. however, these patterns, except the latter one, may be considered as non-specific as heterogeneous echotexture and shadowing calcification can also be detected in malignant testicular tumors. the onion peel pattern of epidermoid cyst correlates well with the pathologic finding of multiple layers of keratin debris produced by the lining of the epidermoid cyst. this sonographic appearance should be considered characteristic of an epidermoid cyst and corresponds to the natural evolution of the cyst. absence of vascular flow is another important feature that is helpful in differentiation of epidermoid cyst from other solid intratesticular lesions. extratesticular tumors although most of the extratesticular lesions are benign, malignancy does occur; the most common malignant tumors in infants and children are rhabdomyosarcomas. other malignant tumors include liposarcoma, leiomyosarcoma, malignant fibrous histiocytoma and mesothelioma. rhabdomyosarcoma rhabdomyosarcoma (a) longituidinal section (composite image) of high resolution ultrasound of a 14-year-old boy shows a well defined hypoechoic extratesticular mass is found in the left scrotum, hydrocele is also present. (b) color doppler ultrasound shows that the mass is hypervascular. rhabdomyosarcoma is the most common tumor of the lower genitourinary tract in children in the 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 with or without hydrocele. with color doppler sonography these tumors are generally hypervascular. mesothelioma mesothelioma arising from the tunica vaginalis. color doppler ultrasound demonstrates a well-defined hypoechoic nodule occupying the left epididymal head, with a few areas of color flow demonstrated. the left testis is intact with no focal nodule detected. hydrocele is also present. 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 . leiomyoma leiomyoma arising from tunica albuginea. (a) montage of 2 contiguous sonograms of a 67-year-old man shows a well-defined extratesticular mass with a whorl-shaped echotexture. (b) color doppler sonogram shows no internal vascularity. note the presence of multiple shadows not associated with echogenic foci in the mass. 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 of the nodule and multiple, narrow areas of shadowing not cast by calcifications , but corresponding to transition zones between the various tissue components of the mass are characteristic of leiomyoma and may help differentiate it from other scrotal tumors. lipoma lipoma at spermatic cord and testiscle. (a) longitudinal scrotal sonography of a 61-year-old patient shows a well defined hyperechoic nodule is seen in the scrotum. (b) scrotal sonography of the same patient shows a hyper echoic nodule in the left testis, pathology proved that this is a lipoma too. lipoma is the most common nontesticular intrascrotal tumor. it can be divided into 3 types depending upon the site of origination and spread: originating in the spermatic cord with spread to the scrotum; originating and developing within the cord (most common type) and originating and developing within the scrotum. at ultrasound, lipoma is a well–defined, homogeneous, hyperechoic paratesticular lesion of varying size . the simple finding of an echogenic fatty mass within the inguinal canal, while suggestive of a lipoma, should also raise a question of fat from the omentum secondary to an inguinal hernia. however lipomas are well-defined masses, whereas herniated omentum appears to be more elongated and can be traced to the inguinal area, hence scanning along the inguinal canal as well as the scrotum is necessary to make the differential diagnosis. magnetic resonance imaging and computerized tomography are helpful in doubtful cases. liposarcoma malignant extratesticular tumors are rare. most of the malignant tumors are solid and have nonspecific features on ultrasonography. the majority of the malignant extratesticular tumors arise from spermatic cord with liposarcoma being the most common in adults. on gross specimen, liposarcoma is a solid, bulky lipomatous tumor with heterogeneous architecture, often containing areas of calcification. although the sonographic appearances of liposarcoma are variable and nonspecific, it still provides a clue about the presence of lipomatous matrix. echogenic areas corresponding to fat often associated with poor sound transmission and areas of heterogeneous echogenicity corresponding to nonlipomatous component are present. some liposarcomas may also mimic the sonographic appearance of lipomas and hernias that contain omentum, but lipomas are generally smaller and more homogeneous and hernias are elongated masses that can often be traced back to the inguinal canal. ct and mr imaging are more specific, as they can easily recognize fatty component along with other soft tissue component more clearly than ultrasound. liposarcoma. a heterogeneous mass consists of an upper hyperechoic portion corresponds to lipomatous matrix and areas of hypoechogenicity corresponds to nonlipomatous component is seen. fig. 16. liposarcoma mimicking lipoma. a homogeneous hypoechoic mass presents with the same appearance of lipoma, rapid growth of this tumors grants surgical intervention with pathology proved to be well differentiated liposarcoma. adenomatoid tumor adenomatoid tumor at epididymis. a nodule that is isoechoic to the testis is seen occupying nearly the entire epididymal tail. adenomatoid tumors are the most common tumors of the epididymis and account for approximately 30% of all paratesticular neoplasms, second only to lipoma. they are usually unilateral, more common on the left side, and usually involve the epididymal tail. adenomatoid tumor typically occurs in men during the third and fourth decades of life. patients usually present with a painless scrotal mass that is 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 . 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. 18. fibrous pseudotumor. a homogeneous hypoechoic nodular lesion is seen attached to the tunica associated with minimal amount of hydrocele. fig. 19. fibrous pseudotumor. with color doppler, a little vascular flow is seen in this fibrous pseudotumor. inflammation epididymitis and epididymo-orchitis epididymo-orchitis in a 77-year-old man. (a) transverse sonography shows enlargement of the epididymis with hypoechogenicity noted over the testis and epididymis associated with scrotal wall thickening. (b) color doppler sonography showed hyperemic change of the testis and epididymis, presenting as an “inferno” vascular flow pattern. 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