Introduction
Background
Classification of malignant tumors of the testicle
Germ cell tumors (GCTs) account for nearly all (95%) of primary testicular tumors. The GCT line is fairly evenly split between seminomas (45%) and nonseminomas (50%). Of the nonseminomas, mixed GCTs are most common (40%). Teratomas and teratocarcinomas are considered malignant in adults and constitute 30% of nonseminomatous lesions. The embryonal cell tumor is the classic pure-cell, nonseminomatous tumor and is relatively uncommon (20%). Choriocarcinoma represents the most lethal but least common (1%) nonseminomatous type.
Both computed tomography (CT) scanning and ultrasonography have been used to search for metastatic retroperitoneal lymphadenopathy, but CT scanning is more commonly used.
This is a seminoma. Sometimes epididymal invasion can be noted on sonograms.
Yolk sac tumors, which are also known as endodermal sinus tumors, are the most common prepubertal GCTs. They may be benign, but most often, they are malignant. Most affected patients require surgery and chemotherapy because of the aggressive nature of the tumors, but the overall prognosis is excellent.
Among nongerminal testicular tumors, stromal Leydig cell tumors and Sertoli cell tumors constitute the remaining 5% of primary testicular tumors; these are rare tumors that are malignant in only about 10% of the cases.
Lymphoma, leukemia, and melanoma are the most common malignancies that metastasize to the testicle.1
Screening for testicular cancer
Ultrasonographic screening for testicular cancer is not currently recommended, because this disease does not meet the criteria for an acceptable screening program wherein early treatment must have a success rate superior to that of the treatment initiated when the patient is clinically symptomatic.
For cancer screening to be successful, the screening tool must be highly sensitive and specific, widely available, cost-effective, and acceptable to the patients. Also, the test must allow clinicians to identify disease at a stage where they can improve the patient's clinical outcome and/or clearly identify patients at risk.
Screening for testicular cancer is not a current recommendation because patients with stage 1 or 2 (2A or 2B) testicular cancer have a long-term, disease-free survival rate greater than 95%; in patients with bulky retroperitoneal nodes and/or pulmonary or visceral metastasis, this rate is 60-80%. A birth-cohort effect is observed for testicular cancer in the United States and Europe, but the etiology of this effect is not known. The false-negative rate for ultrasonographic identification of testicular lesions is extremely low.
Pathophysiology
The specific pathophysiologic mechanisms for neoplasm induction have not been described, but testicular cancer is thought to result from the differentiation of totipotential germ cells. Studies of cancer in familial groups suggest that discordant tumor histology occurs in only 20% of identical twin pairs, whereas the discordance rate is 67% in sibling pairs. Thus, evidence supports a familial tendency toward testicular malignancy.2
A current molecular model suggests that mutations in the 12p chromosomal segment of the malignant cell sequences are associated with tumor development.3 Patients with ambiguous genitalia have the highest risk of testicular malignancy. Among patients with a known testicular cancer, the metachronous risk in the contralateral testicle is 5%. The malignancy risk in men with cryptorchidism is 2-4%, and the risk in patients with subfertility is 1% or less.4
The precise malignancy risk associated with testicular microlithiasis (>5 microcalcifications within a testicle) is unclear. Retrospective studies5 of patients with known malignancy or ultrasound for a clinical finding demonstrate high concordance between microlithiasis and malignancy, but results from a prospective analysis show only a 5-10% risk of coexisting tumors.6
Mature-appearing testicular teratomas are considered malignant in adults but benign in children.
Frequency
United States
Testicular cancer is the most common solid malignancy in males aged 18-35 years and currently represents 1% of all cancers in men. McKiernan et al reported that the rate of testicular cancer increased by 51% between 1973 and 1995.7 Strong evidence suggests a birth-cohort effect, but the etiology of this cohort has not been elucidated.
International
Carcinoma in situ (CIS) is reported to occur in less than 1% of healthy males. Incidence studies in Europe reveal a similar increase in the frequency of disease over the past 40 years.
Mortality/Morbidity
- Seminoma is highly curable when detected early. The 5-year survival is reported to be 95% for stage I disease and 85-90% for stage 2 disease.
- For nonseminomatous germ cell tumors, the results are less favorable, with a 5-year survival rate of 86% for stage I disease. The corresponding survival rate for teratocarcinomas is only 70%.
- Choriocarcinoma has a dismal prognosis; almost no patients survive 5 years after the disease presentation. Choriocarcinomas have the worst prognosis of all the testicular malignancies.
Race
Testicular cancer primarily affects white males. Blacks rarely develop this cancer: 9 cases per million population, compared with 50 cases per million population in other racial groups.
Sex
Patients with ambiguous genitalia have a 25% risk of developing testicular malignancy.
Age
Testicular cancer is the most common solid malignancy in males aged 18-35 years. Seminomas, which peak in the fourth or fifth decade of life, are most common at the extremes of age. Choriocarcinomas are most commonly reported in those aged 10-30 years. Yolk sac tumors are usually composed of pure cell lines and most often seen in patients younger than 3 years.8
Presentation
Staging of testicular cancer
- Stage 1: Confined to the testicle and the spermatic cord
- Stage 2: Includes metastatic lymph nodes below the diaphragm
- Stage 2A: Involves nonpalpable nodes
- Stage 2B: Involves bulky adenopathy
- Stage 3: Metastasis above the diaphragm
- Stage 3A: Confined to the lymph nodes
- Stage 3B: Extra total metastasis
Carcinoma in situ
At the time of the initial surgery, CIS is found in approximately 5% of obtained biopsy samples of the contralateral testicle. The natural history of CIS is progression to frank malignancy at 5 years in 50% of cases. However, the literature does not support routine biopsy of the opposite testis in cases of testicular cancer. The adverse effects of castration are high, and the ease with which the tumors are treated suggests thatsurveillance with treatment of early tumors is preferred.
Differential diagnosis
The differential diagnosis of intratesticular masses includes several entities. Epidermoid cysts of the testicle are seen as a round, sharply demarcated lesion in the testicle. Dilated rete testes are clusters of testicular mediastinal dilated tubules that empty into the epididymis and are often associated with epididymal cysts. Testicular abscess is commonly linked with severe epididymitis, pain, fever, and redness and induration of the scrotum. Hematoma can be associated with a history of testicular trauma, and one must be certain that these findings completely resolve, because incidental trauma is often the presentation for a subsymptomatic testicular mass.9
Hormonal changes
Most of the hormonal abnormalities in seminomas are elevated beta–human chorionic gonadotropin (HCG) levels; thus, the presence of elevated alpha1-fetoprotein levels decrease the likelihood that a tumor is a seminoma. Increased hormone levels occur in about 8% of patients with seminomas and 60% of those with nonseminomatous cancers.
Preferred Examination
Ultrasonography is the standard imaging technique used to identify testicular carcinoma. It has a high sensitivity, but it must be combined with physical examination to achieve the best specificity. More than 95% of testicular parenchymal abnormalities are identifiable on routine sonograms, but several other lesions commonly mimic testicular cancer. Ultrasonography is more specific in the presence of a palpable mass. Nonpalpable intratesticular lesions larger than 1 cm are unlikely to be malignant.
Differential Diagnoses
Other Problems to Be Considered
Abscess or focal orchitis
Focal atrophy
Hematoma
Infarct
Tubular ectasia of the rete testes
Sarcoid
Metastases from lymphoma or leukemia
More on Testicle, Malignant Tumors |
 Overview: Testicle, Malignant Tumors |
| Imaging: Testicle, Malignant Tumors |
| Follow-up: Testicle, Malignant Tumors |
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References
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Keywords
malignant testicular tumors, testicular germ cell tumors, germ cell tumors, GCTs, seminomas, nonseminomas, teratomas, teratocarcinomas, testicular metastases, primary testicular tumors, testicular cancer, embryonal cell tumors, choriocarcinomas, yolk sac tumors, endodermal sinus tumors, nongerminal testicular tumors, stromal Leydig cell tumors, Sertoli cell tumors
