The significance of giant cells in human testicular seminomas. A clinico-pathological study

Decoding germ cell tumours for clinicians

PURPOSE OF REVIEW

Germ-cell tumours of the testis affect predominantly younger males aged between 15 and 40 years, with nearly 74,500 new cases estimated globally in 2020. Their rarity and the complex morphology, mean that, in nonexpert hands, there is a significant risk of misdiagnosis of both type and staging of these neoplasms.

RECENT FINDINGS

There have been significant changes in the 2016 WHO classification of Testicular tumours that need to be understood by both pathologists and clinicians for streamlining management. Standardised structured reporting guidelines and discussion at the multidisciplinary-team meetings lead to subsequently better health outcomes and patient safety.

SUMMARY

Therefore, communication with high-quality reports and understanding of clinicians of what constitutes an adequate report, is the key to ensure proper management of these patients. We attempt to discuss the key updates and pathological features that influence management and need to be communicated with clarity and precision.

The hot-spot p53R172H mutant promotes formation of giant spermatogonia triggered by DNA damage

Overexpression of mutant p53 is a common finding in most cancers but testicular tumours accumulate wild-type p53 (wtp53). In contrast to the accepted concept that p53 homozygous mutant mice do not accumulate mutant p53 in normal cells, our study on a mutant p53 mouse model of Li-Fraumeni syndrome harbouring the hot-spot p53R172H mutation described an elevated level of mutant p53 in non-cancerous mouse tissues. Here we use detailed immunohistochemical analysis to document the expression of p53R172H in mouse testis. In developing and adult testes, p53R172H was expressed in gonocytes, type A, Int, B spermatogonia as well as in pre-Sertoli cells and Leydig cells but was undetectable in spermatocytes and spermatids. A similar staining pattern was demonstrated for wtp53. However, the intensity of wtp53 staining was generally weaker than that of p53R172H, which indicates that the expression of p53R172H can be a surrogate marker of p53 gene transcription. Comparing the responses of wtp53 and p53R172H to irradiation, we found persistent DNA double-strand breaks in p53R172H testes and the formation of giant spermatogonia (GSG) following persistent DNA damage in p53R172H and p53-null mice. Strikingly, we found that p53R172H promotes spontaneous formation of GSG in non-stressed p53R172H ageing mice. Two types of GSG: Viable and Degenerative GSG were defined. We elucidate the factors involved in the formation of GSG: the loss of p53 function is a requirement for the formation of GSG whereas DNA damage acts as a promoting trigger. The formation of GSG does not translate to higher efficacy of testicular tumorigenesis arising from mutant p53 cells, which might be due to the presence of delayed-onset of p53-independent apoptosis.

DNA hypomethylation and aberrant expression of the human endogenous retrovirus ERVWE1/syncytin-1 in seminomas

BACKGROUND

Syncytin-1 and 2, human fusogenic glycoproteins encoded by the env genes of the endogenous retroviral loci ERVWE1 and ERVFRDE1, respectively, contribute to the differentiation of multinucleated syncytiotrophoblast in chorionic villi. In non-trophoblastic cells, however, the expression of syncytins has to be suppressed to avoid potential pathogenic effects. Previously, we have shown that the transcriptional suppression of ERVWE1 promoter is controlled epigenetically by DNA methylation and chromatin modifications. In this study, we describe the aberrant expression of syncytin-1 in biopsies of testicular germ cell tumors.

RESULTS

We found efficient expression and splicing of syncytin-1 in seminomas and mixed germ cell tumors with seminoma component. Although another fusogenic gene, syncytin-2 was also derepressed in seminomas, its expression was significantly lower than that of syncytin-1. Neither the transcription factor GCM1 nor the increased copy number of ERVWE1 were sufficient for this aberrant expression of syncytin-1 in seminomas. In accordance with our recent finding of the highly increased expression of TET1 dioxygenase in most seminomas, the ERVWE1 promoter was significantly hypomethylated in comparison with the matched controls. In contrast, 5-hydroxymethylcytosine levels were not detectable at the ERVWE1 promoter. We further describe that another endogenous retroviral element adjacent to ERVWE1 remains transcriptionally suppressed and two additional HERV-W family members are only slightly upregulated in seminomas.

CONCLUSIONS

We conclude that DNA demethylation of the ERVWE1 promoter in seminomas is a prerequisite for syncytin-1 derepression. We propose the spliced syncytin-1 expression as a marker of seminoma and suggest that aberrant expression of endogenous retroviruses might be a correlate of the hypomethylated genome of seminomas.

The World Health Organization 2016 classification of testicular germ cell tumours: a review and update from the International Society of Urological Pathology Testis Consultation Panel

Since the last World Health Organization (WHO) classification scheme for tumours of the urinary tract and male genital organs, there have been a number of advances in the understanding, classification, immunohistochemistry and genetics of testicular germ cell tumours. The updated 2016 draft classification was discussed at an International Society of Urological Pathology Consultation on Testicular and Penile Cancer. This review addresses the main updates to germ cell tumour classification. Major changes include a pathogenetically derived classification using germ cell neoplasia in situ (GCNIS) as a new name for the precursor lesion, and the distinction of prepubertal tumours (non-GCNIS-derived) from postpubertal-type tumours (GCNIS-derived), acknowledging the existence of rare benign prepubertal-type teratomas in the postpubertal testis. Spermatocytic tumour is adopted as a replacement for spermatocytic seminoma, to avoid potential confusion with the unrelated usual seminoma. The spectrum of trophoblastic tumours arising in the setting of testicular germ cell tumour continues to expand, to include epithelioid and placental site trophoblastic tumours analogous to those of the gynaecological tract. Currently, reporting of anaplasia (seminoma or spermatocytic tumour) or immaturity (teratoma) is not required, as these do not have demonstrable prognostic importance. In contrast, overgrowth of a teratomatous component (somatic-type malignancy) and sarcomatous change in spermatocytic tumour indicate more aggressive behaviour, and should be reported.

Choriogonadotropin positive seminoma-a clinicopathological and molecular genetic study of 15 cases

The presence of human chorionic gonadotropin (hCG) positive syncytiotrophoblastic cells (STC) in classic seminoma (CS) is well documented. CS with extensive hCG positive, non-syncytiotrophoblastic tumour cells (without STC) is exceptionally rare. In this study, we present 15 such cases. 168 CSs were retrieved from the Plzen Tumor registry. Cases of mixed germ cell tumors (with CS) and CSs with typical STC were excluded. Cases with completely embedded tumor mass were selected for further study and immunohistochemically examined with anti-hCG. Positive cases were further analyzed by reverse transcriptase polymerase chain reaction. Two groups of hCG-positive CSs were identified. Group 1 comprised 10 patients with a mean patient age of 37.7 years and mean tumor size of 4.96 cm. Eight cases were pT1 (TMN 2009) and 2 cases pT3a. Blood levels of hCG were elevated in 6 of the 10 patients preoperatively. In 2 patients the blood level of hCG was not tested. Mean follow-up period was 6.1 years. No metastatic behavior was noted. All tumors were extensively immunoreactive for hCG in more than 60% of tumor cells. The expression of hCG beta subunit (CGB)-mRNA in tumor tissue was documented. Group 2: Comprised 5 patients with a mean age was 34 years. Mean tumor size was 4.7 cm. Four cases were stage pT1 and 1 case was pT2. The mean follow-up period was 3.1 years. No metastatic behavior was noted. Preoperative blood levels of hCG were elevated in 1/5 of the patient. Strong hCG positivity was limited to scattered single tumor cells distributed throughout the entire tumor. Only weak expression of CGB mRNA was detected. We can conclude that immunohistochemical detection of expression of hCG in CS is not limited to syncytiotrophoblastic cells. In this study, we report two immunohistochemical patterns of hCG expression in classic seminomas: diffuse hCG staining in the majority of tumor cells and scattered hCG-positive cells within the tumor.

Analysis of poly(ADP-ribose) polymerase-1 (PARP1) gene alteration in human germ cell tumor cell lines

The poly(ADP-ribose) polymerase-1 protein (PARP-1) functions in DNA repair, maintenance of genomic stability, induction of cell death, and transcriptional regulation. We previously analyzed alterations of the PARP1 gene in 16 specimens of human germ cell tumors, and found a heterozygous sequence alteration that causes the amino acid substitution Met129Thr (M129T) in both tumor and normal tissues in a single patient. In this study, aberration of the PARP1 gene and protein was further analyzed in human germ cell tumor cell lines. We found a nonheterozygous sequence alteration that causes the amino acid substitution Glu251Lys (E251K) located at a conserved peptide stretch of PARP-1 in cell line NEC8. Sequencing of 95 samples from Japanese healthy volunteers revealed that all the samples were homozygous for the wild-type alleles at M129T and E251K. The M129T allele is thus suggested to be a rare single-nucleotide polymorphism (SNP). We observed a decrease in auto-poly(ADP-ribosyl)ation activity of PARP-1 proteins harboring M129T or E251K amino acid substitution, but the difference was not statistically significant. The levels of PARP-1 and poly(ADP-ribosyl)ation were heterogeneous among germ cell tumor cell lines. The SNPs of the PARP1 gene, as well as differences in the levels of PARP-1 and poly(ADP-ribosyl)ation of proteins, may influence germ cell tumor development and responses to chemotherapy and radiotherapy.

The Frequency and Distribution of Intratubular Trophoblast in Association With Germ Cell Tumors of the Testis

Although the presence of intratubular trophoblast (ITT) has been reported, its frequency and distribution in association with germ cell tumors (GCT) have not been investigated. Beta human chorionic gonadotropin (hCG) is a sensitive immunohistochemical marker of syncytiotrophoblast. We therefore wished to investigate whether intratubular trophoblastic elements could be identified adjacent to invasive tumors using immunohistochemistry against hCG. Seventy-five GCTs were examined. Immunochemistry was performed for hCG. Both invasive tumor and seminiferous tubules were examined for positive staining. The seminomas showed ITT in five of 29 cases. All these cases had trophoblastic cells as part of the invasive tumor. Only one of 36 cases of nonseminoma and one of nine of the mixed GCTs (11%) showed ITT. Again, all of the positive cases had hCG-positive trophoblastic cells within the invasive tumor. ITT can be identified adjacent to GCTs in a significant number of cases. We suggest that this is a genuine in situ lesion, associated with seminomas with syncytiotrophoblastic cells. Differentiation toward trophoblastic elements in GCTs may occur at an earlier stage of their pathogenesis than has been previously recognized.

Germ cell tumors of the gonads: a selective review emphasizing problems in differential diagnosis, newly appreciated, and controversial issues

Gonadal germ cell tumors continue to be the cause of diverse, diagnostically challenging issues for the pathologist, and their correct resolution often has major important therapeutic and prognostic implications. They are academically interesting because of the biological diversity exhibited in the two gonads and variation in frequency of certain neoplasms. The most dramatic examples of the latter are the frequency of dermoid cyst in the ovary compared to the testis and the reverse pertaining to embryonal carcinoma. Within the teratoma group, there is strong evidence that ovarian and prepubertal testicular teratomas are derived from benign germ cells, a pathogenesis that likely applies also to the rare dermoid cysts and uncommon epidermoid cysts of the testis. In contrast, postpubertal testicular teratomas derive from malignant germ cells, specifically representing differentiation within a preexistent nonteratomatous cancer. As expected, given the foregoing, teratomas in boys are clinically benign, whereas in postpubertal males they are malignant, independent of their degree of immaturity. On the other hand, immaturity is an important finding in ovarian teratomas, irrespective of age, although its significance in children has recently been challenged. It is usually recognized on the basis of embryonic-appearing neuroepithelium, which shows mitotic activity and apoptosis in contrast to differentiated neuroepithelial tissues, which may occur in mature ovarian teratomas. Rarely it is based on the presence of cellular, mitotically active glial tissue. Fetal-type tissues alone are not sufficient for a diagnosis of immature teratoma. Further differences between the teratomatous tumors in the two gonads are the relative frequency of monodermal teratomas in the ovary in contrast to the testis, where only one subset, carcinoids, is seen with any frequency. When uncommon somatic-type malignancies (usually squamous cell carcinoma) occur in mature cystic teratomas of the ovary, this is a de novo form of malignant transformation; similar tumors in the testis, a very rare event, represent overgrowth of teratomatous elements that originated from malignant, nonteratomatous germ cell tumors and, therefore, had previously undergone malignant transformation. Germinomas may have several unusual features in each gonad; these include microcystic arrangements that suggest yolk sac tumor, tubular patterns that mimic Sertoli cell tumor, apparent increased cytological atypia that causes concern for embryonal carcinoma, and prominent syncytiotrophoblast giant cells that suggest choriocarcinoma. Awareness of these variants, good technical preparations, the retained typical cytological features of germinoma cells, and the judicious use of tailored panels of immunohistochemical stains resolve these dilemmas in virtually all instances. Two aspects of germinomas are unique to the testis. Firstly, intertubular growth of small seminomas may cause them to be overlooked. Secondly, the distinctive spermatocytic seminoma occurs only in the testis. A newly recognized aspect of this tumor is the propensity for some to be relatively monomorphic, making them apt to be mistaken for usual seminoma or embryonal carcinoma, although the characteristic polymorphic appearance in some foci, absence of intratubular germ cell neoplasia, unclassified type, and immunohistochemical stains should prevent this error. Cytoplasmic membrane immunoreactivity for placental alkaline phosphatase and CD117, with usual negativity for AE1/AE3 cytokeratins, is helpful in the diagnosis of germinoma. The recently described marker, OCT3/4, a nuclear transcription factor, is especially helpful in the differential of germinoma and embryonal carcinoma with other neoplasms. Yolk sac tumor continues to be confused occasionally with clear cell carcinoma of the ovary. Glandular ('endometrioid-like') yolk sac tumors mimic endometrioid carcinomas; predominant or pure hepatoid yolk sac tumors cause concern for metastatic hepatocellular carcinoma or, in the ovary, primary hepatoid carcinoma, and solid patterns, especially in limited samplings, may be misinterpreted as germinoma. The usually younger age of patients with yolk sac tumors helps with the differential considerations with the nongerm cell tumors, as do other clinical and microscopic features and selected immunohistochemical stains. Choriocarcinoma is rare in both gonads, and those in the ovary must be distinguished from metastatic tumors of placental origin. Syncytiotrophoblast cells alone, admixed with other forms of germ cell tumor, still are confused with choriocarcinoma, but this phenomenon, which is much more frequent than choriocarcinoma, lacks the plexiform arrangement of different trophoblast cell types that typifies the latter. Mixed germ cell tumors (which may show almost any combination of components) are common in the testis but rare in the ovary. A separately categorized, rare form of mixed germ cell tumor seen in both gonads is the polyembryoma. It is perhaps the most photogenic of all gonadal germ cell tumors and is also intriguing because of its distinctive, organized arrangement of yolk sac tumor and embryonal carcinoma elements and recapitulation of very early embryonic development, even to the extent of having in its fundamental unit, the embryoid body, a miniature yolk sac, and amniotic cavity. These tumors, which are constituted by innumerable embryoid bodies, almost always contain teratomatous glands in minor amounts, and one way of viewing the polyembryoma is to consider it the most immature form of teratoma. Embryoid bodies are also common as a minor component of many mixed germ cell tumors, particularly in the testis, and the diffuse embryoma is another variant that has a particular arrangement of yolk sac tumor and embryonal carcinoma elements. Regression of gonadal germ cell tumors is a phenomenon restricted to the testis, for unknown reasons. These so-called 'burnt-out' germ cell tumors can be recognized by a distinctive constellation of findings, including sometimes minor foci of residual recognizable germ cell neoplasia, a well-defined zone of scarring (often having residual ghost tubules), associated lymphoplasmacytic infiltrate, intratubular calcification and, in about 50%, of in situ germ cell neoplasia.

Epidermal growth factor receptor is a marker for syncytiotrophoblastic cells in testicular germ cell tumors

The epidermal growth factor receptor (EGFR) has been implicated in the pathogenesis, therapy and prognosis of various tumor types. The aim of this study was to investigate EGFR expression in a large series of testicular germ cell tumors (TGCTs). A total of 88 TGCTs (37 of pure type and 51 of mixed type) comprising a total of 44 seminoma, 49 embryonal carcinoma, 32 yolk sac tumor, 28 teratoma and 7 choriocarcinoma components were immunostained for EGFR. EGFR reactivity was observed in the stromal cells of embryonal carcinoma (29%) and in epithelial compartments of teratoma (71%). In addition, EGFR staining was consistently detected in syncytiotrophoblastic cells of choriocarcinoma, seminoma, embryonal carcinoma and yolk sac tumor components. EGFR staining, similar to beta-human chorionic gonadotropin (HCG) immunohistochemistry, was efficiently able to identify syncytiotrophoblastic cells in TGCTs. This study shows that EGFR is expressed in a subset of testicular germ cell tumors and suggests that EGFR may be a useful marker for syncytiotrophoblastic cells.

Involvement of poly(ADP-ribose) polymerase in trophoblastic cell differentiation during tumorigenesis

Poly(ADP-ribose) polymerase (Parp) monitors DNA strand breaks and poly(ADP-ribosyl)ates nuclear proteins using NAD as a substrate. The participation of Parp in DNA damage responses has been demonstrated by recent studies using Parp knockout mice. On the other hand, accumulated evidence has shown that Parp is involved in the regulation of gene expression and cell differentiation. In this study, the role of Parp in tumorigenesis and differentiation was studied with Parp-/- embryonic stem (ES) cells. When Parp+/+, Parp+/-, and Parp-/- ES cells were injected subcutaneously into nude mice, teratocarcinoma-like tumors developed from ES cells. However, only tumors derived from Parp-/- ES cells showed trophoblast giant cells (TGCs) containing single or multiple megalo-nuclei. These TGCs are located in a large blood-lake like hemorrhage. This example suggests that Parp is not essential for tumor formation, however, it is involved in trophoblastic cell differentiation and could consequently affect tumor phenotype.

Syncytiotrophoblastic giant cells in teratocarcinoma-like tumors derived from Parp-disrupted mouse embryonic stem cells

The enzyme poly(ADP-ribose) polymerase (Parp) catalyzes poly(ADP-ribosyl)ation reaction and is involved in DNA repair and cell death induction upon DNA damages. Meanwhile, poly(ADP-ribosyl)ation of chromosome-associated proteins is suggested to be implicated in the regulation of gene expression and cellular differentiation, both of which are important in tumorigenesis. To investigate directly the role of Parp deficiency in tumorigenicity and differentiation of embryonic stem (ES) cells during tumor formation, studies were conducted by using wild-type J1 (Parp(+/+)) ES cells and Parp(+/-) and Parp(-/-) ES clones generated by disrupting Parp exon 1. These ES cells, irrespective of the Parp genotype, produced tumors phenotypically similar to teratocarcinoma when injected s.c. into nude mice. Remarkably, all tumors derived from Parp(-/-) clones contained syncytiotrophoblastic giant cells (STGCs), which possess single or multiple megalo-nuclei. The STGCs were present within large areas of intratumoral hemorrhage. In contrast, neither STGC nor hemorrhage was observed in tumors of both wild-type J1 cells and Parp(+/-) clones. Electron microscopic examination showed that the STGCs possess microvilli on the cell surface and contained secretory granules in the cytoplasm. Furthermore, the cytoplasms of STGCs were strongly stained with antibody against mouse prolactin, which could similarly stain trophoblasts in placenta. These morphological and histochemical features indicate that the STGCs in teratocarcinoma-like tumors derived from Parp(-/-) clones belong to the trophoblast cell lineage. Our findings thus suggest that differentiation of ES cells into STGCs was possibly induced by the lack of Parp during the development of teratocarcinoma.

Classification and pathology of testicular germ cell and sex cord-stromal tumors

Germ cell tumors of the testis are the most frequent testicular neoplasms, with seminoma predominating. The pathologist must be able to discriminate between seminoma and nonseminomatous germ cell tumors as well as sex cord-stromal tumors and metastatic lesions. Appropriate therapy and accurate prognostic information are dependent on the proper classification of testicular neoplasia. Characteristic histologic features, serum markers, and immunohistochemistry are helpful in this regard. Sex cord-stromal tumors comprise a small minority of testicular neoplasms. It remains critically important not to confuse these neoplasms with testicular germ cell or metastatic tumors, and, again, recognition of the characteristic histologic features, immunohistochemical findings, and clinical information is diagnostic. The urologist can provide the pathologist with key clinical information in the attempt to make a correct diagnosis.

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.

Trophoblastic tumors of the testis other than classic choriocarcinoma: "monophasic" choriocarcinoma and placental site trophoblastic tumor: a report of two cases

We report two unusual forms of testicular trophoblastic tumor. One was a mixed germ cell tumor in a 19-year-old man that had a predominant component of nodules of cytotrophoblast cells with only rare syncytiotrophoblast cells. These nodules of "monophasic" choriocarcinoma were diffusely positive for human chorionic gonadotropin (hCG), which stained the syncytiotrophoblast cells more intensely; stains for human placental lactogen (HPL) highlighted only the latter cells. The second tumor occurred in a 16-month-old boy. It consisted of a pure proliferation of intermediate trophoblast cells and was identical to the placental site trophoblastic tumor of the uterus. The tumor cells showed diffuse immunoreactivity for HPL and patchy staining for hCG. Despite the occurrence of vascular wall invasion, the patient was alive and well at 8 years follow-up with no treatment other than orchiectomy. These cases show that trophoblastic tumors other than classic choriocarcinoma occur rarely in the testis. The differential diagnosis of the "monophasic" choriocarcinoma included seminoma and the solid variant of yolk sac tumor, but the tumor had larger, more irregular nuclei than those of seminoma and was not associated with distinctive yolk sac tumor patterns. The placental site trophoblastic tumor may be confused with Leydig cell tumor or choriocarcinoma, but awareness of its occurrence in the testis and the immunohistochemical findings should permit its recognition.

Hyperplasia and hypertrophy of Leydig cells associated with testicular germ cell tumours containing syncytiotrophoblastic giant cells

In patients with seminomas and non-seminomatous germ cell tumours of the testis syncytiotrophoblastic giant cells (STGC) are largely responsible for elevated levels of chorionic gonadotropin. In searching for these cells, the question arises whether hyperplasia and/or hypertrophy of Leydig cells in the adjacent testicular tissue is a relevant finding. To elucidate this problem we analysed the tumour-free testicular tissue of 20 seminomas and 20 combined seminomatous and non-seminomatous germ cell tumours with or without immunohistochemically demonstrable STGC morphometrically. Extension of Leydig cell areas and the surface areas of Leydig cells per tubule are increased significantly in seminomas and combined tumours when STGC are present. There is also an apparent increase in the number of Leydig cells per tubule in seminomas and combined germ cell tumours with STGC. The difference, however, is not significant statistically in the group of seminomas. Hypertrophy and/or hyperplasia of Leydig cells must be considered as a relevant finding in germ cell tumours with STGC. It is most easily recorded by evaluating the surface area of Leydig cells per test area or per tubule.

HLA-antigen distribution in seminoma, HCG-positive seminoma and non-seminomatous tumours of the testis

Histocompatibility antigens play a certain role in the development of testicular tumours. 151 patients with testicular cancer (86 non-seminomatous germ cell tumours--NSGCT--and 65 pure seminoma) were typed for the HLA-antigens of the A, B, C and DR locus. 24 patients of the pure seminoma group and 50 patients of the NSGCT group had an elevated serum HCG level preoperatively. The antigen DR-5 was elevated in the seminoma group whereas the incidence of B-13 was increased in the NSGCT group. In terms of antigen distribution HCG-positive seminoma resembles seminomatous tumours rather than NSGCT.

Evidence for free beta-subunit secretion in so-called human chorionic gonadotropin-positive seminoma

In 349 patients with pure seminoma the authors determined human chorionic gonadotropin (HCG) plus the free beta-subunit (HCG-beta) by a polyclonal radioimmunoassay (RIA) and found elevated serum levels in 42 patients (12%). In addition, each HCG and HCG-beta were specifically measured by monoclonal immunoradiometric assays (IRMA) in 19 of these patients. Overall 12 patients were HCG-beta positive and 12 HCG positive. Elevated serum levels of both molecules were found in five patients, whereas seven patients showed elevation only in HCG and another seven patients only in HCG-beta. In serum samples of patients with high HCG-beta and minimally elevated HCG levels the free beta-subunit could be detected by gel filtration and immunoradiometric assays, whereas both HCG-beta and holo-HCG were found in ultrafiltered and concentrated urinary samples. The authors conclude that HCG-beta can be present as the major form in serum even if both HCG-beta and HCG are detectable in urine. When measuring hormone concentration as a tumor marker in seminoma patients, methods which determine both activities, HCG plus HCG-beta, seem to be the most reliable. Whereas 16 patients with Stage I-IIc had HCG-beta levels between 0.1 and 2.8 IU/l and currently have no evidence of disease, two patients with Stage IV had HCG-beta levels of 18 and 37 IU/l and died. Current investigations have to clarify the prognostic significance of beta-subunit secretion.

Malignant mixed germ-cell-sex cord-stromal tumors of the ovary associated with isosexual precocious puberty

Two cases of hormonally active, metastasizing malignant mixed germ cell-sex cord-stromal tumors are described in otherwise normal prepubertal girls. Isosexual precocity was noted 5 months and 1 month before surgery. One child died 1 year after presentation, and the other was alive, with no apparent tumor, 1 year after diagnosis. These two cases represent the first recorded instance of a unique tumor in which metastases of several cell types were encountered.

Ultrastructure of syncytiotrophoblast-like cells in seminomas of the testis

An ultrastructural examination of five syncytiotrophoblast-like cells (STLC) from three otherwise pure seminomas was performed. All five STLC demonstrated ultrastructural features identical to those of normal syncytiotrophoblastic cells. The STLC were surrounded by sinusoidal spaces and cells whose ultrastructure was compatible with that of seminoma cells, though the presence of cytotrophoblastic cells cannot be excluded with certainty. We conclude that STLC in seminomas are indeed syncytiotrophoblastic and their genesis remains an enigma.

Intermediate filaments and desmosomal plaque proteins in testicular seminomas and non-seminomatous germ cell tumours as revealed by immunohistochemistry

Seminomas and non-seminomatous testicular germ cell tumours were studied for the presence of cytokeratin and vimentin filaments and desmosomes using immunohistochemical methods. In the majority of the classical seminomas and in seminomatous area of mixed tumours most tumour cells appeared to lack cytokeratin filaments. Some seminomas contained a focally variable proportion of cells exhibiting cytokeratin-positive structures while other cases contained only few seminoma cells with a well developed fibrillar cytokeratin network. Gel electrophoresis of cytoskeletal proteins from microdissected regions revealed cytokeratin polypeptides nos. 8 and 18 typical of simple epithelia. In one seminoma, however, all, or almost all, tumour cells contained cytokeratin filaments. This finding is in line with the assumption of transitional forms between seminoma and embryonal carcinoma. Despite the lack - or variable expression - of cytokeratin filaments most seminoma cells contained desmosomes, although often few in number and irregularly distributed at the circumference of the cells. Loosely arranged and often very sparse vimentin fibrils were found in many, but not all seminoma cells. Double label immunofluorescence microscopy suggested that the majority of desmosomes was associated with intermediate filaments of the vimentin type. In contrast, in carcinoma cells of malignant teratomas, in well differentiated epithelial cells of intermediate-type malignant teratomas and in trophoblastic cells present in trophoblastic-type malignant teratomas cytokeratin filament bundles as well as desmosomes were decorated. The arrangement and density of the cytokeratin filament skeleton and of desmosomes varied with degree of maturation of the tissue. The most regular distribution and intensive staining of cytokeratin filaments and desmoplakin was found in "mature" tissues. Vimentin was demonstrated in mesenchymal areas and stroma cells. The results show that seminomas are distinguished from most other germ cell and non-germ cell tumours by the presence of true desmosomes together with scanty vimentin filaments in most tumour cells. In addition, they indicate that seminoma cells can be heterogeneous in their cytoskeletal complement and may include cells with cytokeratin expression, indicative of a multipotential character of the initially transformed cell(s).