Материал: Advanced Imaging of the Abdomen - Jovitas Skucas

nous route. Overall, metastases to the testes are uncommon. Prostatic, appendiceal or colonic signet ring carcinomas and a rare renal cell carcinoma have spread via the spermatic cord. Anecdotal metastatic bile duct carcinomas are reported.

Metastases tend to be multiple. Ultrasonography reveals variable echogenicity.

Lymphoma/Leukemia

Primary testicular lymphoma occurs in all age groups but is not common. In distinction to other testicular tumors, secondary lymphoma occurs in older men; lymphoma should be considered if an elderly man develops a testicular tumor. Almost all secondary malignant lymphomas are non-Hodgkin’s B-cell lymphomas. In an occasional patient testicular lymphoma is a first manifestation for this tumor.

Lymphomas and leukemic involvement tend to be bilateral. They range from focal to diffuse infiltration. Ultrasonography reveals a hypoechoic, homogeneous focal or diffuse tumor, similar to germ cell tumors. Associated adenopathy is common, and the epididymis and spermatic cord are also often involved.

Lymphomas tend to be hypointense relative to hydrocele fluid on MR. Similar to lymphomas elsewhere, a homogeneous appearance is common.

Testicular involvement in leukemia is common, especially during recurrence. During remission leukemic cells may persist in the testis in spite of adequate chemotherapy. Leukemia manifests as testicular enlargement. Imaging reveals diffuse infiltration, similar to primary tumors.

Myeloma

A testicular plasmacytoma is rare. It is more common to find testicular infiltration as part of multiple myeloma.

Hemangioma

Both testicular and extratesticular cavernous hemangiomas are rare, and only anecdotal reports exist. Most are detected as palpable nodules and a malignancy is suspected clinically. Hemangiomas have similar imaging findings to the unrelated rare paratesticular

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epithelioid hemangioendothelioma; it has a good prognosis.

Ultrasonography of hemangiomas ranges from nondiagnostic to a heterogeneous tumor replacing parenchyma. Most are hypoechoic, but their echogenicity varies. Some hemangiomas contain calcifications. Color Doppler US of one revealed intense flow in the tumor and normal flow in the surrounding parenchyma (86). Ultrasonography of extratesticular hemangiomas tends to suggest a varicocele.

These hemangiomas are slightly hyperintense on T1and markedly hyperintense on T2weighted images. Any thrombi appear as signal voids.

Extratesticular Tumors

Ultrasonography can differentiate most testicular from extratesticular tumors. Whether an extratesticular tumor originates from the epididymis is more problematic. Ultrasonography cannot differentiate the considerably more common benign extratesticular tumors from a malignant one.

Mesenchymal Tumors

Lumped under this heading are mesotheliomaorigin tumors, various sarcomas, and their benign counterparts. Most originate in the spermatic cord or epididymis. Some undoubtedly are a component of a teratoma.

Over 90% of spermatic cord neoplasms are of mesenchymal origin.

Adenomatoid Tumor/Nonpapillary

Benign Mesothelioma

The most common benign neoplasm involving epididymis is an adenomatoid tumor, also known as a nonpapillary benign mesothelioma. A rare adenomatoid tumor originates in the testis or spermatic cord. Immunohistochemical study suggests a mesothelial cell origin (87). Occurring in adults, these slow-growing tumors are most common in young men; many are asymptomatic.

These tumors vary in their imaging appearance. Most are solid and well marginated, but an occasional one is predominantly cystic. Varying amounts of fibrosis are common. They range from hyperto mostly isoechoic in appearance.

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Some invade adjacent testis and mimic a carcinoma, although testicular malignancies do not typically have an isoechoic appearance.

Malignant Mesothelioma

Malignant mesotheliomas of the tunica vaginalis are uncommon, affecting men over age 50 years.Anecdotal synchronous bilateral malignant mesotheliomas are reported. An association exists with prior asbestos exposure. These tumors range from an aggressive course to more indolent ones. Histologic differentiation from a benign adenomatoid tumor is difficult.

These are solid, nodular tumors. They spread primarily via lymphatics; one of the few remaining indications for a lymphogram is in the workup of a malignant mesothelioma.

Complete tumor excision should be curative.

Benign Mesenchymal Tumors

Lipomas are common extratesticular and spermatic cord tumor. Some of these tumors are complex, containing other mesenchymal tissue. Occurring over a wide age range, many are discovered incidentally.

A lipoma appears as fat density on CT and as a hyperechoic tumor on US. Magnetic resonance reveals a relatively homogeneous hyperintense tumor on T1-weighted images; some lipomas are hyperintense to fat on T2-weighted images.

A rare scrotal tumor of unknown etiology consists primarily of fibrosis and is nonneoplastic in origin. Most of these fibromas are hyperechoic on US. Some have a striated appearance. Magnetic resonance reveals a hypointense tumor on T1and an inhomogeneous hypointense tumor on T2-weighted images. They tend to have inhomogeneous contrast enhancement.

Aggressive fibromatosis (desmoid tumor) of the spermatic cord is rare; histologically these tumors are similar to other desmoid tumors found in the abdomen and are associated with Gardner’s syndrome. These tumors recur following local excision.

Sarcoma

Paratesticular rhabdomyosarcomas occur in infants and children, while leiomyosarcomas

are more common in adults. Rhabdomyosarcomas are mostly solid and occasionally partly cystic, and mimic benign neoplasms. A rhabdomyosarcoma should be considered in children with a paratesticular cystic tumor containing a solid component. Some of these tumors are associated with a hydrocele.

The rare liposarcoma is most common in the spermatic cord (88); some are associated with surrounded inflammation and fibrosis.

The term malignant mesenchymoma appears appropriate for some of these tumors; an occasional one contains such elements as a liposarcoma, chondrosarcoma, and even osteosarcoma.

With most of these tumors preoperative imaging discloses a nonspecific intrascrotal, paratesticular tumor. Ultrasonography and MR reveal a homogeneous tumor indistinguishable but separate from a normal testis. A similar appearance is seen with benign mesenchymal tumors, which, statistically, are more common in this location.

A rare paratesticular tumor is reactive pseudosarcomatous myofibroblastic proliferation (proliferative funiculitis). It is of unknown etiology, although prior trauma appears to be a factor.

Adenoma

Histologically, an adenoma is similar to a welldifferentiated renal cell carcinoma and a multicystic papillary adenocarcinoma of the rete testis, thus metastasis is in the differential diagnosis. This tumor is associated with von HippelLindau disease, at times occurring bilaterally. In the presence of other, more ominous systemic tumors found in von Hippel-Lindau disease, most of these cystadenomas are asymptomatic.

These adenomas range from solid to mostly cystic with papillary soft tissue projections.

Metastasis

Detection of an epithelial malignant neoplasm in the spermatic cord most often represents a metastasis. Even in an asymptomatic patient, a search for a primary site is warranted. A spermatic cord adenocarcinoma is occasionally a first manifestation of a silent colon cancer.

Calcifications

Testicular

The term microlithiasis implies microscopic calcifications that should not be visible with imaging, but this term has become ingrained in medical and radiologic usage for the faint, barely perceptible calcifications detected with high-resolution imaging and is used in this context here. Pathologically, these calcifications either consist of amorphous calcific debris or, more often, are laminated (77); most are multiple. They appear to represent a defect in Sertoli cell phagocytosis of tubular debris. The prevalence of testicular microlithiasis in a population referred for scrotal US was <1% (89).

Testicular calcifications occur in a number of benign conditions and malignancies, in boys and in adults (Table 13.8). In some individuals microlithiasis is discovered as an incidental finding. The relative risk of a concurrent tumor being present is about 22-fold compared to controls (89). Some calcifications are premalignant; neoplasms developing later in some of these individuals, with time interval between discovery of microlithiasis and subsequent neoplasm detection ranging up to a decade.

Table 13.8. Conditions associated with testicular calcifications

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Typically, US reveals testicular microlithiasis as numerous diffuse, small, nonshadowing hyperechoic foci throughout the parenchyma. A tendency toward a peripheral location is evident with some. Any clustering of calcifications should suggest a malignancy.

Although the approach to incidentally discovered microlithiasis varies, an initial clinical evaluation for a silent malignancy, including CT of the chest and abdomen, appears reasonable. Some investigators follow these patients with serial imaging and tumor markers (a- fetoprotein and b-hCG), although sufficient data are not available to provide firm recommendations.

Extratesticular

Prostatic calcifications are common. Occasionally during a bone scan uptake of Tc-99m- MDP, radiotracer is detected around prostatic calcifications; presumably this tissue is metabolically active.

Calcifications develop in some extratesticular benign tumors. The sequela of a hematocele has already been mentioned. Some calcifications are loose in the tunica vaginalis sac; the literature refers to these as scrotal pearls. An occasional such calcification floats in a hydrocele.

Idiopathic

Cryptorchidism

Klinefelter’s syndrome

Down syndrome

Infection/inflammation

Tuberculosis

Filariasis

Granulomatous orchitis

Sarcoidosis

Neoplasms

In association with pulmonary microlithiasis

Epidermoid cysts

Ischemia

Trauma

Prior testicular torsion

Vasculitis

Hematoma

Infertility

Vascular Abnormalities

Varicocele (Spermatic Vein)

Clinical

A varicocele consists of either a single enlarged vein or several freely communicating veins containing incompetent valves. The primary importance of a varicocele is its association with infertility and testicular hypotrophy, although at times a varicocele leads to pain. Only a minority of men with a varicocele are infertile, however, and it is not possible to predict among teenagers with a newly discovered varicocele who will become infertile.

In younger men most varicoceles are idiopathic, but a secondary cause is more common in older individuals. At times an extrinsic tumor, such as a left-sided renal cell carcinoma, compresses or occludes the testicular vein and

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first manifests as a left varicocele. Rarer conditions include hydronephrosis and malignant lymphadenopathy adjacent to the veins.

Varicocele prevalence gradually increases in teenagers, reaching adult levels at about the age of 18 years. In the pediatric age group a varicocele is often associated with a small testis. Testicular growth can be expected after therapy. In infertile men with varicoceles both testicles tend to be atrophic, and sperm motility is low. Correction of a varicocele in an adult often produces poor results, thus the emphasis on early detection.

Varicoceles are more common on the left, although in infertile men varicoceles are most often bilateral. A large study found 87% of individuals to have left varicoceles only, 2% right varicoceles, and 11% bilateral varicoceles (90). The more common left varicocele typically drains into the left renal vein. With an isolated right varicocele, compression of the right spermatic vein by an extrinsic tumor should be considered. Most right varicoceles join the inferior vena cava just inferior to the right renal vein, but aberrant drainage pathways are not uncommon; communication with the paravertebral veins or portal venous system, especially left colic vein, is found in a minority (91). Detection of these alternate pathways aids in reducing recurrence after therapy. A minority of varicoceles are intratesticular in location.

Idiopathic thrombosis of a varicocele is rare (92); clinically, on an acute basis it mimics a strangulated inguinal hernia or testicular torsion.

Imaging

Gray-scale US reveals most varicoceles as dilated, tubular blood-filled structures. Venography identifies testicular (internal spermatic) vein insufficiency by showing reflux of contrast from the left renal vein into the testicular vein and pampiniform plexus.

The internal spermatic vein becomes palpable at a diameter of about 3 to 3.5mm and Doppler US detects reversal of venous blood flow in veins wider than about 3.5mm, realizing that clinical and US diagnoses of a varicocele do not always agree. Although Doppler US does detect a subclinical varicocele, its sensitivity probably is less than that of venography. Also,

the borderland between normal diameter and a varicocele is not clearly defined. Does venous reflux always signify a varicocele?

A rare varicocele is intratesticular and simply represents a dilated intratesticular vein. These intratesticular varicoceles range from bilateral to unilateral, and about half are not associated with an extratesticular varicocele. Ultrasonography detects these varicoceles as dilated serpiginous intratesticular veins close to the mediastinum testis. Doppler US confirms a lowflow state, which varies with the Valsalva maneuver. Care is necessary with US to differentiate between an intratesticular varicocele and tubular ectasia.

Magnetic resonance imaging of an intratesticular varicocele reveals a tortuous tubular structure hypointense on T1and T2-weighted images; it had the same signal intensity as testicular parenchyma. The more common extratesticular varicoceles have a serpiginous course and a varied signal intensity, depending on flow. They enhance on immediate postcontrast images.

Scintigraphy is not commonly used to evaluate varicoceles. Occasionally detected is retrograde blood flow in the internal spermatic vein. Relative blood-pool activity in each hemiscrotum appears to correlate with the presence of a palpable varicocele, but the relevance of such scintigraphy is not established.

Venography not only detects a varicocele but also is used for therapy. Detachable balloons, coils, and a number of foreign materials have been tried with varying success rates.

During a Valsalva maneuver while upright, infrared thermometry reveals an increase in scrotal temperature in those with a varicocele; after internal spermatic vein ligation, the scrotal temperature decreases to that of controls.

Therapy

Considerable evidence suggests that early varicocele treatment in pubertal boys prevents testicular growth arrest. Even in adolescents with grade 2 or 3 varicoceles, within a year of varicocele repair the involved testis increases in size. The goal of therapy in individuals with infertility is to improve sperm density and sperm motility. Varicocelectomy even of a unilateral varicocele results in an improvement.

Prior to therapy, it appears worthwhile to ensure that the underlying kidney is normal. Traditional therapy of a varicocele is open extraperitoneal repair. Recurrence is greater with spermatic vein ligation, but the risk of major complications, including testicular ischemia and hydrocele, increases with spermatic cord venous channel ligation. Currently percutaneous embolization using either stain-

less steel occluding spring coils or sclerotherapy is more common.Alternative therapy consists of detachable embolization balloons and laparoscopic varicocelectomy (Fig. 13.12). Initial spermatic vein phlebography helps establish underlying anatomic variants Current evidence suggests that in infertile men no significant difference in outcome exists between surgical ligation and percutaneous embolization.

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A long-term study of almost 1500 patients with varicoceles using basilic vein access achieved a success rate of 82% for sclerotherapy and 84% for a combination of sclerotherapy and embolization (90); therapy could not be performed in 7% of patients due to basilic vein spasm, catheterization difficulties, or anatomic variation. Some published successful percutaneous varicocele treatment rates are >90%.

Persisting or recurrent varicoceles are generally due to collateral vessels. A combination of endovascular occlusive metal coils—which is comparable with surgical ligation, and a sclerosing agent—which diffuses and scleroses collateral veins and thus decreases recurrence, appears superior to separate use of these agents. Others embolize silicone or latex balloons combined with a sclerosing agent.

An intratesticular varicocele was treated by transcatheter embolization of the spermatic vein (93).

Is an intraoperative postligation venogram necessary during varicocelectomy to confirm the completeness of varicocele ligation? Among boys with postoperative recurrent varicoceles, the presence of patent collateral veins missed at initial surgical ligation caused recurrence in 68%, ineffective vein ligation in 27%, and incompetence of extrafunicular plexus in 5% (94); missed collateral veins were due to the presence of either a double or triple spermatic vein, venous bridges across the surgical ligation, or extraperitoneal anastomoses. A minority of individuals have anastomoses with the portal or systemic veins— among others, with the left colic vein, paravertebral venous plexus, inferior mesenteric veins, and splenic veins (91). Following surgical correction, recurrence usually consists of collateral vessels running parallel to the original varicocele. Knowledge of underlying anastomoses is necessary to prevent recurrence after therapy.

Instead of a venogram, some surgeons use Doppler US to identify accessory spermatic veins and evaluate surgical results.

Prostatodynia (Pelvic Venous

Congestion)

Prostatodynia signifies pain referable to the prostate. The relationship between prostatitis

and prostatodynia is murky, and the latter term is occasionally used to describe clinically atypical prostatitis. Prostatodynia is a clinical diagnosis while pelvic venous congestion is an objective finding based on imaging data. Although many men with prostatodynia do have pelvic venous congestion, these terms are not synonymous.

Endorectal US and transperineal color Doppler US detects intrapelvic venous congestion. Typical 3D MR venography findings of pelvic venous congestion consist of dilated and often thickened prostatic capsular veins, pudendal plexus, and the plexus posterior to the bladder. Three-dimensional MR images provide a global view.

Ischemia

The most common cause of testicular ischemia and atrophy is testicular torsion (discussed earlier; see Testicular Torsion). Penile gangrene and necrosis develop in patients with chronic renal failure; presumably gangrene is ischemic in nature due to progressive vascular calcifications (calciphylaxis) induced by secondary hyperparathyroidism developing with chronic renal failure. Other causes include infection, trauma, and some vasculitides, such as polyarteritis nodosa. Emphysematous infarction is a complication of epididymo-orchitis. Testicular infarction develops in sickle cell disease. A relatively new diagnosis is segmental testicular infarction; MR appears to be the imaging modality of choice for this condition, which is treated with watchful waiting and which reveals eventual partial or complete revascularization (95,96). Penile necrosis has been reported after coronary artery bypass graft (97).

Neonatal testicular infarction is rare. These infarctions can be segmental.

Imaging findings early in the course of an infarction tend to mimic those of a neoplasm. Scintigraphic appearance (using Tc-99m- pertechnetate) of scrotal cellulitis has simulated testicular infarction (98).

Ultrasonography of an infarction reveals a diffuse, inhomogeneous echo pattern. At this stage Doppler US reveals hypoperfusion. Without adequate therapy the testes eventually atrophies and often dystrophic calcifications develop.