Материал: Advanced Imaging of the Abdomen - Jovitas Skucas

MALE REPRODUCTIVE ORGANS

sional epididymitis evolves into an epididymal abscess.

Spermatic cord vascularity is increased in acute epididymitis, while testicular blood flow is normal or increased. This increased cord vascularity helps differentiate acute epididymitis from torsion, which has a similar clinical presentation but decreased spermatic cord vascularity.

High-resolution gray-scale US most often reveals an enlarged hypoechoic epididymis. A hydrocele is apparent in some. The testis is also abnormal with an associated orchitis (epididymo-orchitis). With epididymal hemorrhage the epididymis assumes a heterogeneous appearance. Still, some individuals with acute epididymitis have a normal gray-scale US examination and only Doppler US is abnormal. Doppler US detects epididymal hyperperfusion in epididymitis and establishes testicular peak systolic blood velocities in the right and left side (Fig. 13.7). Peak systolic velocity is increased in acute orchitis and epididymitis.

T2-weighted MR signal intensity ranges from hyperto hypointense with acute epididymitis. Use of IV contrast enhancement aids in accentuating changes bilaterally.

Testicular scintigraphy with Tc-99m-pertech- netate discloses varying blood flow patterns. Inflammation results in hyperemia, and any asymmetry should be viewed as abnormal.

In general, an enlarged epididymis and a testicular tumor point to infection rather than neoplasia; most often orchitis extends from epididymitis, while testicular neoplasms involve the epididymis mostly during their later stages. Likewise, scrotal skin thickening and a hydrocele suggest infection.

Chronic

Occasionally acute epididymitis evolves into chronic inflammation and a painless tumor indistinguishable from other scrotal tumors. At times chronic epididymitis leads to fibrosis and an enlarged epididymis having a heterogeneous echo appearance. Other complications of epididymitis include abscess, pyocele, and infarct.

Epididymal tuberculosis has developed into a hard, nontender tumor, at times containing calcifications. Testicular involvement is common. Chlamydial epididymitis has also presented as a solid scrotal tumor. Occasionally encountered is an epididymal Candida abscess. Leukemic infiltration can mimic epididymoorchitis.

Involvement by Behçet’s disease led to recurrent epididymo-orchitis (71).

Figure 13.7. Epididymitis. Transverse Doppler image of right testis and epididymis shows enlarged hypervascular epididymis (arrows) compared to testis (T). (Courtesy of Deborah Rubens MD, University of Rochester.)

Orchitis

Most episodes of orchitis result from extensions of acute epididymitis. In isolated orchitis a viral infection, such as mumps, should be suspected. Neglected testicular torsion or an infected neoplasm are less common causes of orchitis and possible abscess.

An early US finding of orchitis is increased vascularity in the inflamed testis. With progression, the testis enlarges, becomes hypoechoic, and is covered by a thickened, echogenic tunica albuginea. Ultrasonography of focal orchitis shows a mixed or hypoechoic tumor mimicking a neoplasm. A focal region of hypervascularity detected by Doppler US may represent either inflammation or a neoplasm; follow-up US of an inflammation should show return to normal.

Magnetic resonance imaging shows either a focal region or a diffuse heterogeneous decrease in signal intensity on T2-weighted images.

Technetium-99m-pertechnetate scintigraphy of an inguinal hernia can mimic the appearance of orchitis.

Severe infection evolves into suppuration, abscess, or testicular infarction. In general, the imaging findings of a testicular abscess are similar to those of a neoplasm. Often clinical findings and response to therapy distinguish these conditions.

Granulomatous Epididymo-Orchitis

Grouped under granulomatous epididymoorchitis are tuberculosis, brucellosis, syphilis, some fungi, and a rare idiopathic inflammation. From a clinical viewpoint little purpose is served in attempting to differentiate epididymal involvement from orchitis or the more common epididymo-orchitis.

Tuberculosis

Scrotal tuberculosis develops from either hematogenous spread or extension from prostate and seminal vesicle infection. Initial involvement is generally an epididymitis, extending to an epididymo-orchitis and occasionally orchitis, most often unilateral. A common clinical presentation consists of a painless chronic epididymal nodule, and the presence of such a nodule, especially in a setting of infertility, should suggest tuberculous epididymitis. A neoplasm is often in the differential diagnosis of a tuberculoma. An occasional tuberculoma arises as an asymptomatic inguinal spermatic cord nodule. A tubercular pyocele tends to be more heterogeneous than a typical abscess. Some contain internal septations.

Epididymal involvement ranges from nodular to diffuse. A heterogeneous, hypoechoic pattern is most common, followed by a mixed pattern, with a hyperechoic pattern being the least common. Most other infections result in a homogeneous US appearance, and thus an enlarged heterogeneous epididymis should suggest tuberculosis. Testicular involvement ranges from an enlarged hypoechoic testis, to a hypoechoic focus, to multiple small hypoechoic nodules in an enlarged testis. A hydrocele is

ADVANCED IMAGING OF THE ABDOMEN

common. Sinus tracts and calcifications occasionally develop.

Brucellosis

Brucellosis is implicated in 10% to 15% of men with epididymo-orchitis in brucellosis endemic regions of Turkey and Spain. Most involvement is unilateral and ranges from heterogeneous epididymis, to diffuse orchitis, to focal hypoechoic testicular tumors. Doppler US detects increased vascularity. Scrotal wall and tunica albuginea thickening, and a hydrocele are associate findings.

Idiopathic Granulomatous

Idiopathic granulomatous orchitis is a rare inflammatory condition, possibly due to sperm extravasation and resultant reaction. It is rarely bilateral. Imaging findings tend to mimic a testicular cancer. Ultrasonography reveals a solid testicular mass. Calcifications develop within some of these tumors. The diagnosis is usually made after orchiectomy.

Filariasis

Infection with Wuchereria bancrofti (filariasis) is common in some parts of the tropics. Microfilariae from the blood are ingested by mosquitoes, and with further development they eventually evolve into larvae, which are then injected into humans. The nematode resides in human lymphatics, where it incites a lymphangitis and eventual lymphatic obstruction. Occasionally dead nematodes calcify, and imaging reveals small thin, linear strands.

Not all lymphedema is on an infective basis. Occasionally seen is congenital lymphedema. It also develops after surgical dissection and due to lymphatic obstruction by tumors.

Lymphatic obstruction leads to dilated, thinwalled, fluid-filled structures. At times a superimposed bacterial infection develops. Lymphatic rupture leads to lymphoceles, while lymphatic sinuses drain into surrounding tissues, some even forming external sinuses. Eventually extravasated lymph, resultant fibrosis, and other reactive changes lead to a hard, thickened infiltrate mimicking a neoplasm.

Filarial epididymo-orchitis and spermatic cord lymphadenitis are often bilateral. Initially

MALE REPRODUCTIVE ORGANS

the involved spermatic cord enlarges and has a homogeneous, hypoechoic US appearance. Ultrasonography detects dilated lymphatics even in those patients who are still asymptomatic. Associated hydroceles initially are anechoic, but with fibrosis and debris result in a more heterogeneous appearance and tend to mimic a pyocele. At this stage calcified granulomas and surrounding capsular calcifications are common.

Other Infections

Amebiasis involving the scrotum is rare. A hydatid cyst can develop in an undescended testes.

Similar to epididymitis, fungal orchitis is typically encountered in debilitated or diabetic patients. Even scrotal aspergillosis has developed.

Mumps orchitis is not common but should be suspected with a preceding parotitis. These individuals have marked scrotal swelling, fever, and significantly elevated serum C-reactive protein levels.

Some instances of mumps orchitis progress to testicular atrophy.

Fournier’s Gangrene

A necrotizing fasciitis, known as genitoperineal gangrene, perineoscrotal gangrene, necrotizing fasciitis, or Fournier’s gangrene, is a fulminant infective obliterative endarteritis involving the perineum and external genitalia and resulting in progressive necrosis and systemic sepsis. Named after the French dermatologist who first described it in 1883, some authors limit the use of the term Fournier’s gangrene only to a primary infection and not to the more common secondary infections of the genitalia or perineum. Men are primarily affected.A urethral or anorectal source is found in about half; in the other half no cause is identified. Debilitated and diabetic individuals are more often affected, with Fournier’s gangrene occasionally being the initial clinical manifestation of unsuspected diabetes.

Conventional radiography and CT identify subcutaneous emphysema in about half of these individuals. Asymmetric fascial thickening and fat stranding are common imaging findings,

occasionally seen even before subcutaneous emphysema is apparent, and these findings should suggest Fournier’s gangrene. The differential diagnosis includes a scrotal abscess and extension of gas from a more superiorly located source, such as diverticulitis.At times Fournier’s gangrene coexists with an abscess.

These patients represent urologic emergencies. Debridement, antibiotics, and hyperbaric oxygen are the current therapies employed. Mortality remains high despite broad-spectrum antibiotics and aggressive surgical debridement.

Granuloma

Some solid, painful epididymal or vas deferens tumors represent granulomas. A number of these have developed after vasectomy and probably are a tissue reaction to sperm extravasation into surrounding tissues; an occasional one is caused by a foreign-body reaction. Ultrasonography reveals these granulomas to be solid and either isoor hypoechoic. An occasional one eventually calcifies. Some enhance on postcontrast MRI.

Malacoplakia

Malakoplakia of the testis is rare. Occasionally it manifests as painless testicular enlargement. Some men have had a preceding urinary tract bacterial infection.

A testicular cancer is often suspected.

Sarcoidosis

Even in a setting of systemic sarcoidosis, genital involvement is uncommon, although sarcoidosis and inflammatory nodules have presented as extratesticular scrotal tumors. The epididymis tends to be involved more often than the testis. Some affected individuals develop signs and symptoms mimicking epididymitis. A painless tumor develops in others.

Imaging findings are similar to those seen with epididymitis or a testicular neoplasm.

Tumors

Clinical

An extensive differential diagnosis exists for the infant or boy presenting with a scrotal tumor

Table 13.4. Etiology of a painless scrotal tumor in the pediatric age group

Testicular

Neoplasm

Cyst

Congenital malformation

Posttraumatic

Infection/inflammation

Extratesticular

Neoplasm

Cyst

Hematocele

Infection/inflammation

Pachyvaginalitis testis

Sebaceous cyst

Splenogonadal fusion

Source: Adapted from Aragona et al. (72).

(Table 13.4); two peak age groups exist: 0 to 1 year and 13 to 14 years. In adults, most intratesticular tumors are malignant, while most extratesticular tumors tend to be benign.

The most often encountered epididymal tumors are adenomatoid tumors, leiomyomas, and cystadenomas. Men with von HippelLindau disease are at increased risk for epididymal cystadenomas, similar to the increased incidence of broad ligament cystadenomas found in women with this disease. Anyone presenting with bilateral epididymal cystadenomas should be investigated for this disease.

Imaging

Testicular US readily differentiates intratesticular from extratesticular tumors. In further differentiating between benign and malignant tumors in pediatrics, the imaging modality chosen is often US, but the literature provides conflicting data; some authors achieve sensitivities and specificities over 90% in detecting testicular malignancies, but others find poor specificity and believe that the role of US is limited in this differential.

Currently MRI is limited in differentiating among various scrotal tumors.

Cystic Nonneoplastic Conditions

Cysts originate in the epididymis, spermatic cord, tunica vaginalis, and tunica albuginea (Table 13.5). Most are of unknown etiology. One

ADVANCED IMAGING OF THE ABDOMEN

of the tasks of US is to differentiate between intratesticular and extratesticular cysts. The latter are more common.

Testicular Fluid

In addition to the differential diagnoses listed in Table 13.5, fluid is also present in dermoid cysts and mature teratomas with a cystic component, although often these latter have an associated soft tissue component. These cysts vary in size up to several centimeters in diameter. They are smooth and homogeneous in appearance.

Not all testicular cysts are benign. Some testicular neoplasms develop cystic components. In general, a simple, nonpalpable intratesticular cyst is usually followed clinically. If, on the other hand, US detects a solid component, there is internal echogenicity, septa are present, or if a thick cyst wall is detected, a malignancy is more likely.

Simple Testicular Cyst

Simple intratesticular cysts tend to be small and are filled with serous fluid. Ultrasonography

Table 13.5. Scrotal cystic structures

Intratesticular

Testicular neoplasm containing cysts

Simple testicular cyst

Tunica albuginea cyst

Epidermoid cyst

Rete testis dilatation

Abscess

Cystic dysplasia

Extratesticular

Spermatocele

Epididymal cyst

Hydrocele

Hematocele

Cystocele

Lymphocele

Lymphangioma

Epididymal papillary cystadenoma

Abscess

Pyocele

Amebiasis

Vascular

Varicocele

Hemangioma

Arteriovenous malformation

MALE REPRODUCTIVE ORGANS

detects many simple testicular cysts and also aids in differentiating a simple cyst from a neoplasm. These cysts are anechoic, and they have a thin wall and no solid component.

A simple testicular cyst is hypointense on T1and hyperintense on T2-weighted images. The high T2-weighted signal intensity makes some of these cysts isointense to normal surrounding parenchyma.

Typically these cysts are excised without performing an orchidectomy.

Tunica Albuginea Cyst

Tunica albuginea cysts develop within the tunica. Most are small and solitary, and are discovered incidentally. Some are palpable. They contain either serous fluid or blood.

At times due to prior trauma, tunica vaginalis cysts develop between the visceral portion of the tunica vaginalis and the tunica albuginea. Some indent the testis, thus aiding in distinguishing them from a hydrocele.

Ultrasonography suggests a benign cyst if it is unilocular. If the cyst is multilocular and complex, a malignancy is in the differential. Ultrasonography cannot differentiate between tunica albuginea cysts and tunica vaginalis cysts.

Epidermoid Cyst

Epidermoid cysts are believed to be of germ cell origin, possibly representing a teratoma variant differentiating along ectodermal lines. They are benign, occur at any age, and can be bilateral and large. Clinically, they tend to be detected as painless testicular tumors. Some epidermoid cysts are extratesticular in location.

Because these cysts contain cholesterol crystals and other residual debris, US reveals a hypoechoic, well-marginated tumor with a hyperechoic wall. Some have a laminated or concentric ring-like alternating hypoand hyperechoic appearance (73), and some contain calcifications.

Magnetic resonance imaging of a scrotal epidermoid cyst tends to show similar findings to those of an intracranial epidermoid cyst; namely, most are hypointense on T1and hyperintense on T2-weighted images. Some have a peripheral hypointense region on both T1and

T2-weighted images, giving them a bull’s-eye or onion ring appearance.

These are avascular tumors; Doppler US reveals no flow, and they do not enhance postcontrast MR (73).

Although epidermoid cysts can be treated by simple enucleation, with a newly discovered tumor the differential diagnosis often includes a teratoma or a malignancy; imaging cannot differentiate between these entities, and histologic study of surrounding tissue is necessary.

Rete Testis Dilatation (Tubular Ectasia)

Some men develop dilation and possible cysts in the rete testis, at times bilaterally. Most men with this benign condition are over 55 years old, with only a rare case reported in a child; in the latter this condition can be associated with other congenital urinary anomalies and an embryonic malformation is the most likely cause.

Physical examination detects a scrotal tumor typical of a spermatocele.

Ultrasonography reveals a testicular tumor containing multiple small spherical or tubular anechoic or hypoechoic structures with coarse internal echoes without an associated solid component. Cysts, if present, are located in the periphery, in the region of the mediastinum testis. Coexisting epididymal cysts, epididymitis, and spermatoceles are often present. The US appearance, location, and frequently coexisting epididymal abnormality suggest that this condition represents rete testis dilation, probably in association with epididymal obstruction. The rare rete testis adenocarcinoma probably has a similar appearance. Cystic dysplasia of the testis also has a similar US appearance, although cystic dysplasia occurs mostly in children. Dilation of the rete testis is differentiated from a varicocele by the lack of flow, shown by Doppler US.

Magnetic resonance imaging also detects these tumors. They are hypointense on T1and isoto hyperintense on T2-weighted images, in distinction to most testicular tumors, which are hypointense on T2 weighted images. They do not enhance after IV gadolinium.

In some men this condition can be differentiated from a testicular neoplasm on the basis of clinical, US, and MRI findings, and orchiectomy is not necessary to establish the diagnosis.