Spermatocytic Seminoma Research Articles

Diagnostic pitfalls in the histopathological diagnosis of testicular germ cell tumours

Although testicular germ cell tumours are relatively uncommon they are particularly important as they tend to affect young men and even the advanced metastatic form of the disease has a high cure rate. Treatment is based upon accurate histological diagnosis. Whereas classical tumour patterns are well described and recognized, the relative rarity of some tumour types can lead to diagnostic problems in several important areas. This review highlights two such areas—the distinction of embryonal carcinoma from higher cytological grade variants of classical seminoma, especially when combined, and the recognition of spermatocytic seminoma, including its anaplastic variant. The clinical presentation of young and middle-aged men with metastatic disease with an unknown primary site is a common problem for general histopathologists. This review describes an approach to this with reference to the likelihood of a possible germ cell origin. Late relapses of germ cell tumours can show unusual histological patterns, especially of yolk sac tumour elements. The overall role of immunohistochemistry in germ cell tumour diagnosis is discussed.

Nestin, a neuroectodermal stem cell marker molecule, is expressed in Leydig cells of the human testis and in some specific cell types from human testicular tumours.

The intermediate filament protein nestin is predominantly expressed in some stem/progenitor cells and appears to be a useful molecular tool to characterise tumours originating from precursor cells of neuroectodermal and mesenchymal lineages. Leydig cells originate in the adult testis by differentiation from stem cells and express a variety of neural and neuroendocrine markers. The possible expression of the neural stem cell marker nestin in Leydig cells and testicular tumour cells was determined by analysing the patterns of nestin expression in normal and pathological human testes by Western blot and immunohistochemical methods. In normal testis, nestin was found in some vascular endothelial cells, a subset of peritubular spindle-shaped cells and some Leydig cells; spermatogenic and Sertoli cells were unstained. In normal Leydig cells, nestin was distributed in the perinuclear cytoplasm and accumulated in the crystalloids of Reinke with ageing. In non-tumour pathologies (cryptorchidism, impaired spermatogenesis), the seminiferous tubules were immunonegative, whereas hyperplastic Leydig cells showed cytoplasmic immunolabelling. In testicular malignancies, nestin was localised in the Sertoli cells of the seminiferous tubules affected with intratubular germ cell neoplasia, in the hyperplastic Leydig cells associated with these tumours and in some components (mesenchymal and neuroepithelial cells) of teratomas; spermatocytic and non-spermatocytic seminomas were unstained. Some vascular endothelial cells were immunolabelled in all tumour samples. Thus, nestin is expressed in a population of normal and hyperplastic Leydig cells and in Sertoli cells in the presence of intratubular germ-cell neoplasia. Nestin may be a good marker for identifying components of testicular teratomas.

Le séminome spermatocytaire: Étude anatomo-clinique et immunohistochimique de 7 cas

Spermatocytic seminoma is an uncommon tumor, representing less than 1% of the testicular tumors, occurring most often in old patients. We report 7 cases of this entity. The average age at presentation was 66 years. Tumors had a polymorphic appearance with small, intermediate and large cells, and "spireme" figures. They were pure, with no sarcomatous component. In all cases, the tumor was limited to the testis. In the peritumoral tissue, there was no intratubular germ cell proliferation, and no atrophic testis. Immunostaining was negative for all the classical antibodies tested (cytokeratins, PLAP, lymphoid markers), but all the cases expressed c-kit (100%). This membranous positivity was focal in 4 cases, very strong, and diffuse in the 3 others. Spermatocytic seminoma must be recognized, because its favorable evolution in absence of a sarcomatous component. Adequate treatment consists of orchidectomy alone. Positive staining for c-kit may be helpful for the diagnosis of spermatocytic seminoma.

Normal and pathological human testes express hormone-sensitive lipase and the lipid receptors CLA-1/SR-BI and CD36

Numerous studies have demonstrated the important role of cholesterol and cholesteryl esters in tumor cell proliferation and progression of cancer. However, few studies have focused on the role of lipid transporters and lipases in cancer development and progression. The present study examined the expression of hormone-sensitive lipase (HSL) and the scavenger receptors CLA-1/SR-BI and CD36 in normal human testis and in nontumor and tumor testicular disorders by immunohistochemistry and Western blotting analysis. In normal young testes, immunoreaction to CLA-1/SR-BI was found in the spermatid acrosomic vesicle and on the surface of Sertoli and Leydig cells. HSL was detected in spermatogonia, the Golgi region of spermatocytes, the nucleus of spermatids, and the cytoplasm of both Sertoli and Leydig cells. Elderly testes and testes with hypospermatogenesis showed a similar staining pattern to that of normal young testes except for CD36, which was expressed in Sertoli cells. Cryptorchid testes demonstrated intense labeling to HSL and weak labeling to SR-BI in Sertoli cells (nucleus and cytoplasm) and Leydig cells (cytoplasm). Seminiferous tubules with intratubular germ cell neoplasia exhibited intense immunolabeling to the 3 lipid receptors in the surface of neoplastic cells and to HSL in the nucleus. In seminoma and spermatocytic seminoma, neoplastic cells labeled to HSL but failed to stain with antilipid receptors; in the seminiferous tubules at the periphery of the tumour, Charcot-Böttcher crystalloids of Sertoli cells were strongly positive to CLA-1. Testes with mature teratoma showed a weak reaction to CD36 and SR-BI in some cells of enteric-type glands, and immature teratoma were exclusively immunolabeled with HSL. Western blotting analysis revealed that multiple bands were immunolabeled, with differences seen between normal and pathological testes. The results of this study indicate that the presence of lipid receptors (CLA-1/SR-BI) and hormone-sensitive lipase in Leydig cells suggests a role of these proteins in steroidogenesis. Also, these proteins seem to be involved in spermiogenesis, as their labeling in spermatids suggests. In nonmalignant and malignant pathologies, cholesterol metabolism is probably altered, and HSL labeling in neoplastic germ cell nuclei suggests a still-unknown function of this enzyme, probably related to cell cycle regulation.

Detection of chromosomal aberrations in spermatocytic and classical seminoma

SALL4 is one of the master transcriptional factors that are crucial in maintaining the pluripotency of embryonic stem cells (ESCs). While the expression of SALL4 is normally restricted to ESCs and somatic stem cells, we found that it is aberrantly expressed in ALK-positive anaplastic large cell lymphoma (ALK + ALCL), a type of lymphoid malignancy carrying a mature T-cell immunophenotype. shRNA knockdown of SALL4 in ALK + ALCL cell lines resulted in apoptosis and cell-cycle arrest, and significantly decreased colony formation on soft agar. These changes correlated with the downregulation of several anti-apoptotic proteins and facilitators of cell-cycle progression. Based on the differential response to a SALL4 reporter construct, we were able to separate two distinct cell subsets in Karpas 299 (an ALK + ALCL cell line), namely SALL4high and SALL4low. Importantly, the biological effects induced by SALL4 knock-down in Karpas 299 were restricted to the purified SALL4high cells, and this finding further supports the concept that SALL4 is biologically important in ALK + ALCL. Lastly, the expression of SALL4 was not dependent on the nucleophosmin (NPM)-anaplastic lymphoma kinase (ALK)/STAT3 signaling axis, the key oncogenic driver in ALK + ALCL. To conclude, for the first time, our study has revealed the oncogenic contributions of an ESC protein in the pathogenesis of ALK + ALCL.

Spermatocytic seminoma: a review.

Spermatocytic seminoma is a rare testicular tumour that has an extremely low rate of metastasis. We present a review of the management of this malignancy at our institution. Between 1981 and 1999, 771 patients were treated at our institution for testicular seminoma. Of these, 13 had spermatocytic seminoma; one was excluded as he had treatment elsewhere. All patients were initially diagnosed at other hospitals and subsequently referred for management and had their pathology reviewed locally prior to any treatment. All patients had stage I disease, 5 patients received radiotherapy to the para-aortic and pelvic nodes, the other 7 were followed on a surveillance program. The median age was 62 years. With a median follow-up of 8.5 years no relapses were observed. Some patients exhibited adverse histological features associated with increased risk of relapse in seminoma including rete testis invasion and large primary tumour size. Spermatocytic seminoma may occur in younger patients and may not be restricted to the older population as commonly reported. Surveillance following orchidectomy is the preferred management option.

The immunohistochemical expression pattern of Chk2, p53, p19INK4d, MAGE-A4 and other selected antigens provides new evidence for the premeiotic origin of spermatocytic seminoma.

Spermatocytic seminoma is a rare germ cell derived tumour of the testis that occurs mainly in older men. We analysed the expression of recently discovered markers for germ cell differentiation and the mitosis-meiosis transition in order to define the antigen profile for diagnostic purposes and to clarify the biology and histogenesis of spermatocytic seminoma. Twenty-five spermatocytic seminomas were examined for immunohistochemical expression of germ cell-specific onco-fetal antigens and proteins involved in regulation of germ cell division, DNA repair and differentiation. The panel included Chk2, p19INK4d, p53, MAGE-A4, KIT, TRA-1-60, neurone-specific enolase and placental-like alkaline phosphatase. Four of these proteins/antigens have never before been investigated in spermatocytic seminoma. Proteins highly expressed in gonocytes and spermatogonia, such as Chk2, MAGE-A4 and neurone-specific enolase, were consistently present in spermatocytic seminoma. Antigens expressed in embryonic germ cells but not in the normal adult testis, e.g. TRA-1-60, were undetectable, with the exception of p53 protein, which was demonstrated in 80% of cases. A proto-oncogene p19INK4d, which is involved in the transition from mitotic to meiotic division in germ cells, was not detected in spermatocytic seminoma. The investigation provided new information concerning the expression of Chk2, MAGE-A4, neurone-specific enolase and p19INK4d in spermatocytic seminoma. The pattern of expression is highly consistent with the origin of spermatocytic seminoma from a premeiotic germ cell, which has lost embryonic traits and has committed to spermatogenic lineage but has not yet passed the meiotic checkpoint, most probably from the spermatogonium of the adult testis.

VASA is a specific marker for both normal and malignant human germ cells. zeeman a.m., stoop h., boter m., et al.: Laboratory investigation (2002) 82(2):159–166

SUMMARY: VASA is so far the only known gene in mammals whose expression is specific for the germ cell lineage. We investigated the presence of VASA mRNA and protein in a series of germ cell tumors of different histologic subtypes and anatomic location, as well as in non-germ cell tumors such as testicular lymphomas and Leydig cell tumors. We detected VASA mRNA (by quantitative RT-PCR) and protein (by immunohistochemical staining) in normal spermatogenesis, seminoma (both classic and spermatocytic), carcinoma in situ (the precursor of classic seminoma and non seminoma), dysgerminoma, and gonadoblastoma. VASA immunostaining was relatively weak in seminomas and dysgerminomas compared with spermatocytic seminomas, despite similar mRNA levels, suggesting that VASA is regulated in part by posttranscriptional mechanisms. A higher staining intensity compared with the invasive counterparts was observed in the precursor lesions (ie, carcinoma in situ and gonadoblastoma). No VASA mRNA or protein was detectable in nonseminomatous germ cell tumors (such as embryonal carcinoma, teratoma, and yolk sac tumor) and derived cell lines, or non-germ cell tumors such as lymphoma or Leydig cell tumor. These results provide direct evidence that some germ cell tumors retain germ cell characteristics, whereas other tumors of germ cell origin result from differentiation and loss of germ cell identify. Furthermore, these findings suggest that VASA is likely to serve as a useful and highly specific biomarker for germ cell tumors, particularly classic and spermatocytic seminoma/dysgerminoma, including their precursor stages.

Role of gain of 12p in germ cell tumour development.

Within the human testis, three entities of germ cell tumours are distinguished: the teratomas and yolk sac tumors of newborn and infants, the seminomas and nonseminomas of adolescents and young adults, referred to as testicular germ cell tumours (TGCT), and the spermatocytic seminomas. Characteristic chromosomal anomalies have been reported for each group, supporting their distinct pathogenesis. TGCT are the most common cancer in young adult men. The initiating pathogenetic event of these tumours occurs during embryonal development, affecting a primordial germ cell or gonocyte. Despite this intra-uterine initiation, the tumour will only be clinically manifest after puberty, with carcinoma in situ (IS) as the precursor. All invasive TGCT, both seminomas and nonseminomas, as well as CIS cells are aneuploid. The only consistent (structural) chromosomal abnormalities in invasive TGCT are gains of the short arm of chromosome 12, mostly due to isochromosome (i(12p)) formation. This suggests that an increase in copy number of a gene(s) on 12p is associated with the development of a clinically manifest TGCT. Despite the numerous (positional) candidate gene approaches that have been undertaken thus far, identification of a causative gene(s) has been hampered by the fact that most 12p gains involve rather large genomic intervals, containing unmanageable numbers of candidate genes. Several years ago, we initiated a search for 12p candidate genes using TGCT with a restricted 12p-amplification, cytogenetically identified as 12p11.2-p12.1. This approach is mainly based on identification of candidate genes mapped within the shortest region of overlap of amplification (SROA). In this review, data will be presented, which support the model that gain of 12p-sequences is associated with suppression of apoptosis and Sertoli cell-independence of CIS cells. So far, DAD-R is one of the most likely candidate genes involved in this process, possibly via N-glycosylation. Preliminary results on high through-put DNA- and cDNA array analyses of 12p-sequences will be presented.

The Cancer-Testis Gene, NY-ESO-1, Is Expressed in Normal Fetal and Adult Testes and in Spermatocytic Seminomas and Testicular Carcinoma In Situ

Cancer/testis genes are potential targets for therapeutic genetic and immunologic approaches, and are highly expressed in a large variety of human cancers. However, they are not expressed in normal tissues, with the exception of the testis. The NY-ESO-1 gene is the most recently identified member of the cancer/testis family and its product is one of the most immunogenic tumor antigens. We used immunohistochemistry to investigate the expression of NY-ESO-1 in healthy human prenatal and adult testes and in 59 human testicular tumors of different subtypes. We found that NY-ESO-1 was expressed from 18 weeks until birth in human fetal testes. In the adult testis, NY-ESO-1 was strongly expressed in spermatogonia and in primary spermatocytes, but not in post-meiotic cells or in testicular somatic cells. NY-ESO-1 was not expressed in the Sertoli cells, Leydig cells, classical seminomas, or nonseminomatous germ cells in the 59 testicular tumors. In contrast, NY-ESO-1 was expressed both in carcinomas in situ, which are the earliest stage of testicular tumors (7 of 15 cases), and in spermatocytic seminomas, which are believed to be derived from spermatogonia or primary spermatocytes (8 of 16 cases). We conclude that NY-ESO-1 is a marker that can be used to follow the early progression of testicular tumorigenesis when the tumors present a similar pattern of expression to the cells from which they originated, although the later tumors cease to express NY-ESO-1.

VASA Is a Specific Marker for Both Normal and Malignant Human Germ Cells

VASA is so far the only known gene in mammals whose expression is specific for the germ cell lineage. We investigated the presence of VASA mRNA and protein in a series of germ cell tumors of different histologic subtypes and anatomic location, as well as in nongerm cell tumors such as testicular lymphomas and Leydig cell tumors. We detected VASA mRNA (by quantitative RT-PCR) and protein (by immunohistochemical staining) in normal spermatogenesis, seminoma (both classic and spermatocytic), carcinoma in situ (the precursor of classic seminoma and nonseminoma), dysgerminoma, and gonadoblastoma. VASA immunostaining was relatively weak in seminomas and dysgerminomas compared with spermatocytic seminomas, despite similar mRNA levels, suggesting that VASA is regulated in part by post-transcriptional mechanisms. A higher staining intensity compared with the invasive counterparts was observed in the precursor lesions (ie, carcinoma in situ and gonadoblastoma). No VASA mRNA or protein was detectable in nonseminomatous germ cell tumors (such as embryonal carcinoma, teratoma, and yolk sac tumor) and derived cell lines, or nongerm cell tumors such as lymphoma or Leydig cell tumor. These results provide direct evidence that some germ cell tumors retain germ cell characteristics, whereas other tumors of germ cell origin result from differentiation and loss of germ cell identity. Furthermore, these findings suggest that VASA is likely to serve as a useful and highly specific biomarker for germ cell tumors, particularly classic and spermatocytic seminoma/dysgerminoma, including their precursor stages.

Involvement of the Fas/FasL pathway in the pathogenesis of germ cell tumours of the adult testis.

Induction of apoptosis by Fas ligand (FasL) of Fas-containing cells is a known mechanism involved in the eradication of inappropriate cells during normal development. Alterations of the Fas/FasL pathway have been found in various types of cancer, leading to circumvention of attack of the tumour by the immune system. An alternative way to circumvent eradication by induction of apoptosis is through changes in the downstream inhibitors. For example, Fas-associating phosphatase-1 (Fap-1) binds directly to the Fas receptor and results in a block of the downstream signalling. To shed more light on the role of the Fas/FasL pathway in the development of human testicular germ cell tumours of the adult testis, this study investigated the presence of Fas, FasL, Fap-1, HLA class I and II molecules, CD45 (lymphocyte marker), and CD57 [natural killer (NK) cell marker] by immunohistochemistry on frozen sections of 41 cases of seminomas, non-seminomas, and spermatocytic seminomas. Every germ cell tumour was positive for Fap-1 and negative for HLA classes I and II, like their non-malignant cells of origin. The infiltrating lymphocytes, predominantly present in seminomas, showed consistently positive staining for Fas and CD45, but not for Fap-1. No Fas was found on NK cells. All seminomas and non-seminomas (except teratomas), including their precursor stages, carcinoma in situ, intratubular seminoma and intratubular non-seminoma, showed positive staining for FasL, but not for Fas. Teratoma showed no staining for FasL and was positive for Fas. In contrast, both Fas and FasL were detectable on spermatocytic seminoma. These data indicate a different regulation of the Fas/FasL system in seminoma and spermatocytic seminoma, supporting a separate pathogenesis for these germ cell-derived tumours. The presence of Fap-1 in all histological variants of germ cell tumours might be related to the consistently positive staining in cells of the germ lineage. This study indicates that production of FasL by the germ cell tumour cells might be involved in the early development of these types of adult testicular cancer by inducting apoptosis of Fas-positive, Fap-1-negative tumour-infiltrating lymphocytes.

Immunohistochemical expression of monoclonal antibody 43-9F in testicular germ cell tumours.

The aim of this study was to evaluate the clinical utility of immunohistochemical staining of human testicular germ cell tumours with the monoclonal antibody 43-9F to distinguish embryonal carcinoma (EC) from other malignant germ cell components in order to facilitate pathohistological assessment of prognostic risk factors for metastatic disease in clinical stage I NSGCT. Archival, formalin-fixed, paraffin-embedded tissue blocks of 24 classical seminomas, 7 spermatocytic seminomas, and 20 non-seminomatous germ cell tumours were stained for 43-9F, AFP, hCG and PLAP expression. Immunohistochemical expression was graded using a semi-quantitative scoring system: 1+ = 0-25%, 2+ = 26-50%, 3+ = 51-75% and 4+ = 76-100%. Positive immunohistochemical staining for 43-9F was found in all embryonal carcinomas and yolk sac tumours (YST); staining intensity was not statistically different between the two tumours (3.8 +/- 1.2 vs. 3.1 +/- 0.9). Classical seminomas and seminomatous components of NSGCT stained positive in 13/24 cases (54%); staining intensity was weak to moderate (1.1 +/- 0.7) in all but two cases (4+). Spermatocytic seminomas demonstrated weak positive immunostaining in 2/7 cases (29%). Adjacent CIS was found in 33/54 (61.1%) of tumours and 24/33 (72.7%) of CIS cells exhibited a weak to moderate staining intensity (1.4 +/- 0.7). AFP expression was found in 93% of YST and in only 10% of EC; however, based on the focal staining pattern, adequate differentiation of YST and EC was not possible. Positive PLAP staining was observed in 75% of EC, 79% of seminomas and in 88% of CIS cells. We did not find 43-9F staining clinically useful to distinguish embryonal carcinoma from other germ cell tumour components such as yolk sac tumour. The detection rate of CIS by 43-9F immunohistochemical staining was low and combination of PLAP staining with light microscopy was even superior. Additionally, our study confirms the link between pre-invasive CIS and embryonal carcinoma and suggests the possible direct development of embryonal carcinoma from CIS.

Treatment of early stage testicular seminoma

Stage I and IIA/B testicular seminoma represent approximately 45% of all testicular germ cell tumours. Due to the availability of highly efficient salvage treatment, the disease-specific survival in stage I seminoma is approximately 100%, irrespective of the choice of adjuvant treatment. Radiotherapy with 26 Gy to the paraaortic/paracaval lymph nodes yields excellent cure rates of 95 98% with a favourable profile of acute and late toxicity. Likewise, phase-II trials with single-agent carboplatinum systemic treatment have demonstrated a rate of relapse of 3-4% on average. However, carboplatinum chemotherapy has to be regarded as experimental until data of phase-III trials are available. Surveillance in stage I disease is conflicted with a rate of relapse of approximately 20%. However, 80% of the patients will avoid potentially toxic overtreatment by the watch-and-wait policy. In stage IIA/B seminoma, "dogleg" radiotherapy with 30 Gy and 36 Gy, respectively, provides high cure rates of 90-95%. Those patients relapsing will be salvaged in almost 100% of cases. Testicular intraepithelial neoplasia (TIN) is the common precursor lesion of testicular germ cell tumours except for spermatocytic seminoma. In case of TIN in a single testis or bilateral TIN, local radiotherapy with 18 Gy is recommended as standard treatment.

Reactivity of Germ Cell Maturation Stage-Specific Markers in Spermatocytic Seminoma: Diagnostic and Etiological Implications

It is generally accepted that testicular seminomas and spermatocytic seminomas have separate pathogeneses, although the origin of these two types of germ cell tumors of the adult testis remains a matter of debate. Although an embryonic germ cell origin seems to be most likely for seminomas, a spermatogonia-spermatocyte origin has been suggested for spermatocytic seminoma. To shed more light on the etiology of spermatocytic seminomas, we undertook an immunohistochemical and molecular approach using SCP1 (synaptonemal complex protein 1), SSX (synovial sarcoma on X chromosome), and XPA (xeroderma pigmentosum type A) as targets. Although a stage-specific expression pattern has been reported for SCP1 and SSX in normal spermatogenesis, we demonstrate here that it also exists for XPA. In fact, immunohistochemistry shows that the proteins of SCP1 and XPA are specifically present in the stage of primary and pachytene spermatocytes. In contrast, SSX was found in spermatogonia and primary spermatocytes, as well as in germ cells, from at least the 17th week of intrauterine development onward. Although no protein encoded by any of these genes was detected in tumor cells of a series of testicular seminomas, all tested spermatocytic seminomas were positive, in agreement with expression analysis. These data support the model that seminomas originate from an embryonic germ cell, and they imply that the cell of origin of spermatocytic seminomas is at least capable of maturing to the stage of spermatogonia-pachytene spermatocyte.

Comparative Genomic and In Situ Hybridization of Germ Cell Tumors of the Infantile Testis

Chromosomal information on germ cell tumors of the infantile testis, ie, teratomas and yolk sac tumors, is limited and controversial. We studied two teratomas and four yolk sac tumors using comparative genomic hybridization (CGH) and in situ hybridization. No chromosomal anomalies were found in the teratomas by any of the methods, not even after CGH on microdissected tumor cells. All yolk sac tumors showed aneuploidy, loss of parts of 4q and 6q, and gain of parts of 20q. Underrepresentation of parts of 8q and overrepresentation of parts of 3p, 9q, 12p, 17, 19q, and 22 were detected in most cases. In addition, one recurrent yolk sac tumor after a sacral teratoma was studied, showing a highly similar pattern of imbalances. While CGH demonstrated loss of 1p36 in one testicular yolk sac tumor, in situ hybridization revealed loss of this region in all yolk sac tumors. High-level amplification of the 12q13-q14 region was found in one yolk sac tumor. MDM2, of which the encoding gene maps to this chromosomal region, was found in all cases using immunohistochemistry, whereas no p53 could be detected. Accordingly, no mutations within exons 5 to 8 of the p53 gene were observed. These data prove the absence of gross chromosomal aberrations in teratomas of the infantile testis and show a characteristic pattern of gains and losses in the yolk sac tumors. Besides confirmation of previously found anomalies, recurrent losses of 1p21–31 and 4q23–33 and gains of 9q34 and 12p12–13 have not been reported before. While genetic inactivation of p53 seems unimportant in the pathogenesis of these tumors, biochemical inactivation by MDM2 might be involved. These data support the existence of three entities of germ cell tumors of the human testis: teratomas and yolk sac tumors of infants, seminomas and nonseminomas of adolescents and young adults, and spermatocytic seminomas of the elderly, each with its own specific pathogenesis.

Expression of the RNA component of human telomerase in adult testicular germ cell neoplasia

During human development, telomerase is repressed in most somatic cells, whereas it is maintained in male germline cells. Reactivation of telomerase has been associated with somatic cancers. To the authors' knowledge, the role of telomerase in germ cell derived malignancies has not previously been evaluated. A radioactive in situ hybridization method was used to study the expression of the RNA component of human telomerase (hTR) in 22 cases of adult testicular germ cell neoplasia encompassing all major histomorphologic types. For precise cell identification, hTR in situ hybridization was combined with immunohistochemistry in select cases. Testicular germ cell tumors showed differential expression of hTR. The highest level of expression was seen in embryonal carcinoma. Seminoma and unclassified intratubular germ cell neoplasia exhibited moderate levels of expression. Yolk sac tumor was characterized by a range of expression, which mirrored its morphologic variation. Immature teratoma recapitulated the down-regulation of telomerase manifested during human embryogenesis. Mature teratoma represented the adult pattern of somatic repression. Notably, choriocarcinoma showed modest expression. The expression of spermatocytic seminoma was intermediate between that of classic seminoma and embryonal carcinoma. No difference in expression was evident between matching intratubular and invasive components. In nonneoplastic testis, hTR expression was down-regulated during spermatogenesis and was absent in spermatozoa. Expression was negligible in rete testis and interstitial Leydig cells, and low in epididymis. Unexpectedly, Sertoli cells, which are testicular accessory somatic cells, displayed the most intense expression observed in this study. In testicular germ cell tumors of young adults (and during spermatogenesis), hTR expression is down-regulated with differentiation, irrespective of the aggressiveness of the tumors. Spermatocytic seminoma, regarded as a low grade malignancy, shows moderately intense expression.

The value of central histopathological review of testicular tumours before treatment.

To assess the value of central histopathological review of testicular tumours. The histopathology reports of the referring hospital and central review were compared for all referred testicular specimens (201 orchidectomies and seven testicular biopsies) from 11 hospitals in one region, between 1992 and 1997. There were two main findings: First, there was a major discrepancy of tumour type in 12 specimens (6%). The most frequent change (in five cases) was from seminoma to nonseminomatous germ cell tumour (NSGCT). There were also difficulties with uncommon tumours such as spermatocytic seminoma, lymphoma and adenocarcinoma. Treatment was changed as result of the altered diagnosis in eight of these 12 patients. Second, there were discrepancies of interpretation of vascular invasion in 12 of 59 NSGCTs (20%). Differences of tumour elements recognized in NSGCTs were frequent. The errors discovered on central histopathological review of testicular tumours were significant, though small in number. This supports the idea of central review and is consistent with the specialization recommended in the Calman-Hine cancer arrangements.

Pathogenesis of testicular germ cell tumours.

Human germ cell tumours comprise a heterogeneous group of neoplasms. In the testis, three entities are distinguished, the teratomas-yolk sac tumours of the infantile testis, the seminomas and nonseminomas of adolescents and adults, and the spermatocytic seminomas. Studies on epidemiology, histology, clinical behaviour, and chromosomal constitution of these tumours support the concept of distinct entities derived from germ cells but each with a different pathogenesis. Either the teratomas of the infantile testis show no chromosomal aberrations, or display a pattern of over- and under-representation of (parts of) chromosomes as detected in the yolk sac tumours of the infantile testis. In contrast, the seminomas and nonseminomas reveal a consistent pattern of losses and gains, that is, chromosomes 11, 13 and 18, and 7, 8 and X, respectively, that is different from that found in the infantile testis teratomas and yolk sac tumours. The most consistent structural chromosomal abnormality is an isochromosome 12p. Tumours lacking i(12p) have other structural abnormalities of 12p, among them amplification of 12p11.2-p12.1. The pathogenetically relevant genes on 12p11.2-p12.1 are probably on a fragment of about 1.7 mb. Gain of 12p sequences may be related to invasive growth. Gain of chromosome 9 is the only consistent chromosomal anomaly of spermatocytic seminomas. Infantile teratomas and spermatocytic seminomas are benign tumours. Infantile yolk sac tumour is a malignant germ cell tumour. Seminomas and nonseminomas are malignant, and the most common cancer in young Caucasian males. The cure rate of seminomas and non-seminomas with radio- and chemotherapy is over 90%, which is higher than that of any other solid cancer in adults. In addition, the precursor lesions of these tumours can be treated readily, justifying efforts to develop means for early diagnosis. Finally, the pathogenetic relationship between seminomas and nonseminomas, and the available animal models for the three groups of testicular germ cell tumours are discussed.

Ki-A10, a Germ Cell Nuclear Antigen Retained in a Subset of Germ Cell-Derived Tumors

Monoclonal antibody Ki-A10 recognizes a nuclear antigen of 25 and 22 kd apparent molecular mass, which is abundantly expressed by immature gonocytes, spermatogonia, and spermatocytes, whereas it is absent in spermatids, spermatozoa, oocytes, and normal somatic tissues. In a broad spectrum of human cancers the antibody showed no reactivity except for a small subset of malignant lymphomas. Because of this restricted expression pattern, we examined 173 germ cell tumors and 18 sex cord stromal tumors immunohistochemically to assess the distribution of the Ki-A10 antigen. A strongly positive reaction was found in classic seminomas, dysgerminomas, spermatocytic seminomas, and the germ cell component of gonadoblastomas. Yolk sac tumors presented a heterogeneous reactivity pattern ranging from overall positivity to complete lack of antigen expression, and in three of eight choriocarcinomas, a few clusters of cytotrophoblast cells were strongly labeled. All other tumors, including Leydig and Sertoli cell tumors as well as placental tissue, were negative. Our findings suggest that specific germ cell antigens can be retained in germ cell tumors along particular differentiation pathways. Ki-A10 is the first marker that consistently labels spermatocytic seminoma, further confirming its germ cell origin and suggesting a close relationship to classic seminoma. The antibody may serve for diagnostic purposes and promises new insights into the process of germ cell differentiation and the development of germ cell-derived neoplasia.