Contribution of cell proliferative activity to malignancy potential in testicular seminoma

Case of bilateral seminoma in a trotter stallion

This report describes a bilateral seminoma in a stallion. After slaughter, histological examination revealed that the tumour consisted predominantly of polyhedral tumour cells with large nuclei, obvious nucleoli and a small border of cytoplasm. The mitotic index was low and Ki67 staining revealed 4% nuclear staining. To our knowledge, this paper is the first using Ki67 staining as a method to evaluate the mitotic rate in a testicular seminoma in the stallion.

A rare case of classic testicular seminoma in an 86-year-old shows similar proliferation rate as in younger men

We present a rare case of classic seminoma in an 86-year-old man. Combined mitotic count, the presence or absence of intravascular invasion, and the expression of PCNA, Ki67, and p53 were compared between this octogenarian and the tumors of four randomly selected standard younger men. These histologic features were chosen to compare the potential biologic activity of these tumors. The phenotype of classic seminomas in octogenarians seems to be the same as in younger men, and treatment paradigms should remain unchanged.

An overview of testicular germ cell tumors

CONTEXT

More than 90% of testicular neoplasms originate from germ cells. Testicular germ cell tumors (GCTs) are a heterogeneous group of neoplasms with diverse histopathology and clinical behavior.

OBJECTIVE

To help the readers distinguish various subtypes of GCTs, to highlight the clinical manifestations and pathologic features of these tumors, and to review several newly developed immunohistochemical markers for GCTs.

DATA SOURCES

Review of the pertinent literature and our experience.

CONCLUSIONS

The etiology of GCTs is largely unknown. Cytogenetic studies suggest a different pathogenesis for each group of infantile/prepubertal GCTs, postpubertal GCTs, and spermatocytic seminoma. Unclassified intratubular germ cell neoplasia is the precursor of all GCTs, excluding spermatocytic seminoma and infantile/prepubertal GCTs. Seminoma, the most common GCT in adults, does not occur before 5 years of age. Spermatocytic seminoma, a tumor of elderly men, typically has an indolent clinical behavior, but rarely it undergoes sarcomatous transformation associated with an aggressive behavior. Embryonal carcinoma is the most common component in mixed GCTs. Eighty percent or more of embryonal carcinoma component and vascular invasion are recognized predictors of occult metastasis for clinical stage I mixed GCTs. Most patients with prepubertal yolk sac tumor, the most common pediatric GCT, have stage I disease at presentation. Most choriocarcinomas present with metastatic symptoms because of the propensity for rapid hematogenous dissemination. Teratomas in children regardless of maturity and dermoid cysts in adults are benign; in contrast, teratomas in adults have a malignant behavior. With appropriate therapy, the majority of testicular GCTs are curable.

Sonographically documented stable seminoma: a case report

Seminoma of the testis has a diverse natural history. We report a unique case of histologically confirmed classic seminoma in a 32-year-old patient documented by ultrasound on two occasions one year apart. The tumor size did not change during that time. We explore the possibility of a dichotomy in growth within seminoma and the need to identify molecular methods to predict the subset of tumors that behave biologically less aggressive.

MAGE-A4, a germ cell specific marker, is expressed differentially in testicular tumors

BACKGROUND

Testicular germ cell tumors are the most common malignancy in young males, and the frequency of these tumors has risen dramatically over the last century. Because it is known that the MAGE genes are expressed in a wide variety of tumors but are expressed only in the mitotic spermatogonia (germ cells) and in the primary spermatocytes in the normal testis, the authors screened the expression of MAGE-A4 in a panel of testicular germ cell tumors.

METHODS

Monoclonal antibody 57B raised against MAGE-A4 was tested immunohistochemically on 12 classical seminomas, 5 anaplastic seminomas, 10 various specimens of nonseminomatous germ cell tumors (NSGCTs), 2 combined tumors containing seminoma components, 1 Sertoli cell tumor, 2 Leydig cell tumors, and 15 carcinomas in situ (CIS). In addition, monoclonal antibody 57B was tested on embryonic gonad (age 8 weeks) and fetal gonads (ages 15 weeks, 17 weeks, and 28 weeks).

RESULTS

Classical seminomas uniformly and specifically expressed MAGE-A4 compared with anaplastic seminomas and NSGCTs, which were negative for this antigen. Specific expression of MAGE-A4 also was seen in subpopulations of CIS cells, providing additional evidence for heterogeneity of the phenotype of these cells, in which it is believed that differentiation and proliferation generate seminomas and NSGCTs. Finally, MAGE-A4 was expressed in the fetal precursors of the stem germ cells from 17 weeks of gestation onward, in accordance the fact that CIS can arise from prespermatogonia in the fetus.

CONCLUSIONS

MAGE-A4 can be considered a potential specific marker for normal premeiotic germ cells and germ cell tumors and can be used to characterize classical seminomas.

DNA ploidy analysis and cell proliferation in congenital sacrococcygeal teratomas

BACKGROUND

Congenital sacrococcygeal teratoma is the most common germ cell tumor in infants and children. It usually is diagnosed at birth, is benign, and consists of fully differentiated mature tissues. Congenital sacrococcygeal teratomas (SCTs) also may contain immature tissues, most commonly of neural origin. The proportion of malignant teratomas increases with advancing age, but the relation between mature and immature SCTs is not well understood. Thus, it is very important to determine proliferative activity, DNA ploidy, and DNA index to predict biologic behavior of these tumors.

METHODS

DNA ploidy and cell proliferation were analyzed by flow cytometry, and the expression of proliferating cell nuclear antigen (PCNA) and Ki-67 were analyzed immunohistochemically on paraffin embedded tissue.

RESULTS

All the tumors that were surgically treated within 3 months after birth, including immature teratoma, were diploid. Strongly positive PCNA immunostaining was found in both immature teratomas, and weakly positive PCNA was found in nine cases. Weak positivity for Ki-67 was observed in 2 cases, and moderate positivity was observed in 6 cases including immature teratomas.

CONCLUSION

The value of flow cytometry in the prediction of biologic behavior of congenital SCT should be analyzed further. Our results suggest that Ki-67 and especially PCNA may reflect the proliferative activity of these tumors.

Evaluation of cyclin expression in testicular germ cell tumors: cyclin E correlates with tumor type, advanced clinical stage, and pulmonary metastasis

The measurement of proliferative index has yielded promising yet conflicting results in the evaluation of testicular tumors. We have examined the role of Ki-67, along with the cyclins A and E in testicular tumorigenesis. We compared the immunoreactivity of 20 pure seminomas with 20 mixed germ cell tumors composed predominantly of embryonal carcinoma with a variety of proliferation markers, including Ki-67, cyclin A, and cyclin E. All 40 tumors stained for Ki-67, and 19 of 20 (95%) seminomas and 18 of 20 (90%) embryonal carcinomas stained positively for cyclin A. Cyclin E stained 14 of 19 (74%) of the embryonal carcinomas and only 4 of 20 (20%) of the seminomas (Fisher's exact two-tailed test, P = .0012). There was a trend toward larger tumor size for cyclin E-positive seminomas (median, 5.92 cm versus 3.96 cm; P = .08), although the same correlation was not significant in embryonal carcinomas. For both seminomas and embryonal carcinomas, staining with cyclin E did not correlate with the presence of lymphovascular invasion or capsular invasion. However, patients who had cyclin E-positive tumors presented with higher clinical stage (P = .0015). In addition, pulmonary spread in embryonal carcinomas (four patients) and seminomas (one patient) occurred only in patients whose tumors were cyclin E positive (P = .014). Although Ki-67 and cyclin A offer little prognostic information in testicular germ cell tumors, cyclin E immunoreactivity correlates with tumor type and is strongly predictive of distant tumor spread.

Testis risk and prognostic factors. The pathologist's perspective

Pathologic analysis is invaluable in defining the levels of risk for the development of a testicular tumor or for metastasis in a patient with an established testicular cancer. The identification of IGCNU in testicular biopsies defines a group of patients at high risk for subsequent invasive germ cell tumor unless they are treated by orchiectomy or radiotherapy. This method for defining the risk for the development of a testicular tumor is not effective in prepubertal patients, except for those with intersex syndromes. Pathologic analysis of testicular germ cell tumors in patients with clinical stage I disease may allow their stratification into high- and low-risk groups for occult metastases. This would provide a rational basis for recommending intervention or surveillance, respectively. The precise classification of postchemotherapy lesions permits an assessment of the patient's risk for subsequent recurrence and progressive tumor.

Testicular seminoma with human chorionic gonadotropin production

Testicular seminoma with elevated serum human chorionic gonadotropin level (hCG-positive seminoma) is regarded as more malignant than marker-negative seminoma, although its prognosis is still unclear. To clarify the malignant potential of seminoma with hCG production, the serum levels of the beta subunit of hCG (beta-hCG) and lactic acid dehydrogenase (LDH) were examined in 35 and 40 patients, respectively, and the immunohistochemical expression of beta-hCG examined in 45 tumors. The elevation of the LDH serum level correlated to the invasive status, metastatic status and poor outcome, while that of the serum beta-hCG level correlated only to the metastatic status. Immunohistochemical expression of beta-hCG was observed in syncytiotrophoblastic giant cells in 11 tumors and a few mononuclear seminoma cells in 36 tumors. Expression was not associated with the malignancy potential, except where the expression in mononuclear cells inversely correlated to the invasive status. These results suggest that most seminomas produce a slight amount of hCG; that an elevated hCG serum level indicates the presence of metastatic tumors and mainly reflects an increase in tumor volume but not in cellular malignancy potential; and that the LDH serum level, rather than hCG, is more useful as a prognostic indicator for patients with seminoma.

Immunohistochemical analysis of the nm23 gene products in testicular seminoma

The nm23 gene has been identified as a metastasis suppressor gene. To clarify the role of nm23 as a metastasis suppressor gene in testicular seminoma, the expression of the nm23-H1 and -H2 proteins (human nucleoside-diphosphate kinase-A and -B) was immunohistochemically examined in 43 patients. Thirty-six (84%) and 21 (49%) of the 43 primary tumors were positive for the nm23-H1 and -H2 proteins, respectively. There was no significant difference in either nm23-H1 or -H2 expression between the 24 primary non-invasive tumors and the 19 primary invasive tumors, or between the 31 primary tumors without metastasis and the 12 primary tumors with metastasis. In all, and 5 of 6 metastatic tumors, the expression of nm23-H1 and -H2 proteins was observed, respectively, and the expression was not decreased in the metastatic tumors, compared to the primary tumors. In conclusion, the immunohistochemical expression of both the nm23-H1 and -H2 gene products is not associated with the metastatic status or the invasive status of testicular seminoma, and it is unlikely to be a useful non-metastatic indicator for testicular seminoma. Further studies are needed to elucidate the biological role of nm23.