Ultrasonography of extratesticular tumors
Authors:
Mikael Häggström; Authors of integrated Creative Commons article[1] [notes 1]
Contents
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.[1]
Rhabdomyosarcoma
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.[1]
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.[1]
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.[1]
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:[1]
- 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 zones between the various tissue components of the mass are characteristic of leiomyoma and may help differentiate it from other scrotal tumors.[1]
Fat containing tumors
Lipoma
Lipoma is the most common nontesticular intrascrotal tumor. It can be divided into 3 types depending upon the site of origination and spread:[1]
- 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 [Fig. 14]. 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.[1]
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 [Fig. 16] 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. In this case a heterogeneous mass consisting of an upper hyperechoic portion, corresponding to lipomatous matrix, and areas of hypoechogenicity corresponding to nonlipomatous components.[1]
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.[1]
Adenomatoid tumor
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.[1]
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].[1]
Fig. 18. Fibrous pseudotumor. A homogeneous hypoechoic nodular lesion is seen attached to the tunica associated with minimal amount of hydrocele.[1]
Fig. 19. Fibrous pseudotumor. With color Doppler, a little vascular flow is seen in this fibrous pseudotumor.[1]
Notes
- ↑ For a full list of contributors, see article history. Creators of images are attributed at the image description pages, seen by clicking on the images. See Radlines:Authorship for details.
References
- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 1.15 1.16 1.17 1.18 Content originally copied from: Mak, Chee-Wai; Tzeng, Wen-Sheng (2012). Sonography of the Scrotum . doi:. from Kerry Thoirs. Sonography. ISBN 978-953-307-947-9Script error: No such module "check isxn"., Published: February 3, 2012, under the CC-BY-3.0 license.
