Identical allelic losses in mature teratoma and other histologic components of malignant mixed germ cell tumors of the testis

Defining the cellular origin of seminoma by transcriptional and epigenetic mapping to the normal human germline

Aberrant male germline development can lead to the formation of seminoma, a testicular germ cell tumor. Seminomas are biologically similar to primordial germ cells (PGCs) and many bear an isochromosome 12p [i(12p)] with two additional copies of the short arm of chromosome 12. By mapping seminoma transcriptomes and open chromatin landscape onto a normal human male germline trajectory, we find that seminoma resembles premigratory/migratory PGCs; however, it exhibits enhanced germline and pluripotency programs and upregulation of genes involved in apoptosis, angiogenesis, and MAPK/ERK pathways. Using pluripotent stem cell-derived PGCs from Pallister-Killian syndrome patients mosaic for i(12p), we model seminoma and identify gene dosage effects that may contribute to transformation. As murine seminoma models do not exist, our analyses provide critical insights into genetic, cellular, and signaling programs driving seminoma transformation, and the in vitro platform developed herein permits evaluation of additional signals required for seminoma tumorigenesis.

Germ Cell Tumor of the Testis: Lethal Subtypes of a Curable Cancer

Germ cell tumor of the testis (GCT) is a curable cancer even when it is widely metastatic; however, outcomes can differ based on tumor histology. Chemo-resistance in certain phenotypes, such as teratoma and yolk sac tumor, contributes to poor clinical outcomes in some patients with GCT. Despite this resistance to S-YSTemic therapy, many of these tumor subtypes remain amenable to surgical resection and possible cure. In this study, we report on a series of seven patients highlighting two chemo-resistant subtypes of nonseminomatous germ cell tumor (NSGCT), sarcomatoid yolk sac tumor (S-YST), and epithelioid trophoblastic tumor (ETT) for which early resection rather than additional salvage chemotherapy or high-dose intense chemotherapy might provide a superior clinical outcome and enhance cure rate.

Germ cell neoplasms of the testis: Update for 2022

Germ cell neoplasia in situ (GCNIS) is the precursor of both seminomatous and non-seminomatous germ cell tumors. It consists of distended tubules that may have either intratubular seminoma or intratubular embryonal carcinoma cells. Many invasive non-seminomatous tumors contain a mixture of tumor types, which are reviewed here. Morphology, aided by a panel of immunostains, can determine the presence and percent of embryonal carcinoma, yolk sac tumor, choriocarcinoma, or teratoma in such tumors. Use of immunostains, required for diagnosis in perhaps 25% of testicular neoplasms, is reviewed. Changes of classification in the AJCC (8^th edition) in 2016 are discussed, including the partitioning of two tumor types: the central role of chromosome 12p amplification allows both teratoma and yolk sac tumor to be divided into prepubertal types (lacking amplification) and post-pubertal types. Occasionally, sex cord-stromal tumors, hematolymphoid tumors, or epididymal adenomatoid tumors enter the differential diagnosis of germ cell neoplasms.

Differential expression of preferentially expressed antigen in melanoma (PRAME) in testicular germ cell tumors - A comparative study with SOX17

The accurate identification of different components in testicular germ cell tumors (GCT) is essential for tailoring treatment and informing the clinical prognosis. PRAME (preferentially expressed antigen in melanoma), a member in the family of cancer testis antigens, plays critical roles in regulating pluripotency and suppressing somatic/germ cell differentiation in seminomas (SEM). To investigate the potential diagnostic value of PRAME in testicular GCT, here we comparatively examined the expression patterns of PRAME and SOX17 by immunohistochemistry in both pure and mixed GCT. Tissue microarrays constructed from 66 pure or mixed GCT were examined, including 25 seminomas (13 pure and 12 mixed), 35 embryonal carcinomas (EC; 7 pure and 28 mixed), 23 teratomas (TER; 10 pure and 13 mixed), 15 yolk sac tumors (YST; 1 pure and 14 mixed), and 5 choriocarcinomas (CC; 1 pure and 4 mixed), with 11 germ cell neoplasia in situ (GCNIS) and 6 normal testicular tissue as controls. The expression levels of PRAME or SOX17 were evaluated by a scoring system counting for intensity and extent of staining. PRAME nuclear expression was present in 92% (23/25) of SEM, including all 13 pure SEM, and 10 out of 12 seminomatous component of mixed GCT. In contrast, all EC and TER were completely negative for PRAME, and focal expression was demonstrated in 33.3% of YST and 20% of CC. As for SOX17, 96% of SEM and 73% of YST stained positively, whereas EC and CC were negative. Focal nuclear positivity was identified in the epithelial cell component of 17.4% (4/23) of TER. We found the sensitivity of PRAME to detect SEM to be comparable to SOX17, although SOX17 staining is more diffuse and stronger in the majority of cases. The specificity of PRAME for SEM appeared to be superior to that of SOX17 (92% versus 81%). In conclusion, PRAME is preferentially expressed in SEM or within the seminomatous component of mixed GCT with only focal variable expression in YST and CC, but shows no expression in EC and TER. These findings suggest that PRAME can be explored as a diagnostic marker for SEM.

Stem Cell Theory of Cancer: Implications for Drug Resistance and Chemosensitivity in Cancer Care

Simple Summary

Science and history teach us that stemness properties pave all drug resistance pathways. Evidence and experience inform us that stemness origin and nature etch all cancer hallmarks. A stem cell origin of drug resistance encompasses heterogeneity and dormancy, embraces ABC transporters and DNA repairs, and explicates chemotherapy and chronotherapy. It alludes to a unified theory of cancer and suggests that cancer is a stem cell disease—uniting chemoresistance with chemosensitivity, connecting progenitor cells with progeny cells, and linking multicellularity with the microenvironment. Importantly, it clarifies genetic content vs. cellular context, delineates drug vs. therapy development, and enlightens precision medicine vs. integrated medicine and targeted therapy vs. multimodal therapy in cancer care.

Abstract

When it concerns cancer care and cancer therapy, drug resistance is more than an obstacle to successful treatment; it is a major cause of frustration in our attempts to optimize drug development versus therapy development. Importantly, overcoming the challenges of drug resistance may provide invaluable clues about the origin and nature of cancer. From this perspective, we discuss how chemoresistance and chemosensitivity in cancer therapy could be directly linked to the stem cell origin of cancer. A stem cell theory of cancer stipulates that both normal stem cells and cancer stem cells are similarly endowed with robust efflux pumps, potent antiapoptotic mechanisms, redundant DNA repair systems, and abundant antioxidation reserves. Cancer stem cells, like their normal stem cell counterparts, are equipped with the same drug resistance phenotypes (e.g., ABC transporters, anti-apoptotic pathways, and DNA repair mechanisms). Drug resistance, like other cancer hallmarks (e.g., tumor heterogeneity and cancer dormancy), could be intrinsically ingrained and innately embedded within malignancy. We elaborate that cellular context and the microenvironment may attenuate the effects of cancer treatments. We examine the role of circadian rhythms and the value of chronotherapy to maximize efficacy and minimize toxicity. We propose that a stem cell theory of drug resistance and drug sensitivity will ultimately empower us to enhance drug development and enable us to improve therapy development in patient care.

Genetics of congenital solid tumors

When we discuss the genetics of tumors, we cannot fail to remember that in the second decade of the twentieth century, more precisely in 1914, Theodore Boveri defined for the first time the chromosomal bases of cancer. In the last 30 years, progresses in genetics have only confirmed Boveri's remarkable predictions made more than 80 years ago. Before the cloning of the retinoblastoma 1 (RB1) gene, the existence of a genetic component in most, if not all, solid childhood tumors were well known. The existence of familial tumor aggregations has been found much more frequently than researchers expected to find at random. Sometimes, the demonstration of this family predisposition was very difficult, because the survival of children diagnosed as having a certain tumor, up to an age at which reproduction and procreation is possible, was very rare. In recent years, advances in the diagnosis and treatment of these diseases have made it possible for these children to survive until the age when they were able to start their own families, including the ability to procreate. Four distinct groups of so-called cancer genes have been identified: oncogenes, which promote tumor cell proliferation; tumor suppressor genes, which inhibit this growth/proliferation; anti-mutational genes, with a role in deoxyribonucleic acid (DNA) stability; and micro-ribonucleic acid (miRNA) genes, with a role in the posttranscriptional process.

Molecular Characterization of Testicular Germ Cell Tumors Using Tissue Microdissection

Testicular germ cell tumors are among the most common malignancies seen in children and young adults. Genomic studies have identified characteristic molecular profiles in testicular cancer, which are associated with histologic subtypes and may predict clinical behavior including treatment responses. Emerging molecular technologies analyzing tumor genomics, transcriptomics, and proteomics may now guide precision management of testicular tumors. Laser-assisted microdissection methods such as laser capture microdissection efficiently isolate selected tumor cells from routine pathology specimens, avoiding contamination from nontarget cell populations. Laser capture microdissection in combination with next generation sequencing makes precise high throughput genetic evaluation effective and efficient. The use of laser capture microdissection (LCM) for molecular testing may translate into great benefits for the clinical management of patients with testicular cancers. This review discusses application protocols for laser-assisted microdissection to investigate testicular germ cell tumors.

Curing Cancer: Lessons from a Prototype

Simple Summary

Germ cell tumor of the testis (TGCT) teaches us that to cure cancer, we need to acquire and apply proper biological insight and clinical acumen. In 1946, about 90% of patients with metastatic TGCT died within the first year of diagnosis. Today, over 90% of the same patients are curable. This complete reversal in the cure rate of TGCT is not because we have designed better drugs (we have not), but because we have learned how to use the same drugs in the right patients under the right settings. Importantly, TGCT is a prototype stem cell tumor that may hold the key to unlocking the origin of cancers, thereby enhancing our understanding of cancer and improving the cure and care of patients with cancer.

Abstract

Germ cell tumor of the testis (TGCT) is a remarkably curable solid tumor even when it is widely metastatic and patently heterogeneous. It provides invaluable clues about the origin and nature of metastasis and heterogeneity, cancer dormancy and late recurrence, drug sensitivity and resistance, tumor immunity, and spontaneous remission that would enable us to enhance the cure and improve the care of patients with other currently intractable solid tumors. After all, germ cells are primeval stem cells and TGCT are a perfect stem cell tumor for us to investigate a stem cell versus genetic origin of cancer. In many respects, TGCT is a prototype stem cell tumor that will enable us to elucidate the role of differentiation versus dedifferentiation in the evolution of a complex mixed tumor. It will help us decipher relevance of the genome versus the epi-genome in a progenitor cancer stem cell versus a progeny differentiated cancer cell. Importantly, clarification of a cellular context versus the genetic makeup in cancer has immense clinical implications. We postulate a unified theory of cancer derived from seminal TGCT research to improve personalized cancer care. Contrary to current norms and conventional wisdom, we propose that when it concerns a complex rather than simple cancer and a mixed rather than pure tumor (which is practically all solid tumors) multimodal therapy trumps targeted therapy and integrated medicine overrides precision medicine.

Origin of Subsequent Malignant Neoplasms in Patients with History of Testicular Germ Cell Tumor

Simple Summary

Although testicular germ cell tumor (TGCT) carries a high cure rate, some patients still die from it. We investigated the genetic landscape and cellular origins of cancers that develop later in life after treatment for TGCT and found evidence that a common progenitor cell might be responsible for both. This study shows the possible importance of stem-like cells in the development of cancer.

Abstract

Although genetic changes may be pivotal in the origin of cancer, cellular context is paramount. This is particularly relevant in a progenitor germ cell tumor and its differentiated mature teratoma counterpart when it concerns tumor heterogeneity and cancer dormancy in subsequent second malignancies (subsequent malignant neoplasms (SMNs)). From our tumor registry database, we identified 655 testicular germ cell tumor (TGCT) patients who developed SMNs between January 1990 and September 2018. Of the 113 solid organ SMNs, 42 had sufficient tumor tissue available for fluorescence in situ hybridization (FISH) analysis of isochromosome 12p [i(12p)]. We identified seven additional patients for targeted DNA and RNA sequencing of teratomas and adjacent somatic transformation. Finally, we established cell lines from freshly resected post-chemotherapy teratomas and evaluated the cells for stemness expression by flow cytometry and by the formation of teratomas in a xenograft model. In our cohort, SMNs comprising non-germ cell tumors occurred about 18 years after a diagnosis of TGCT. Of the 42 SMNs examined, 5 (12%) contained i(12p) and 16 (38%) had 12p gain. When comparing a teratoma and adjacent somatic transformation, targeted DNA and RNA sequencing demonstrated high concordance. Studies of post-chemotherapy teratoma-derived cell lines revealed cancer-initiating cells expressing multipotency as well as early differentiation markers. For the first time, we demonstrated the prevalence of i(12p) in SMNs and the presence of progenitor cells embedded within mature teratomas after chemotherapy. Our findings suggest a progenitor stem-like cell of origin in SMN and TGCT and highlight the importance of cellular context in this disease.

Fluorescent In Situ Hybridization Analysis for 12p Alterations in Sarcomatoid Yolk Sac Tumors

"Sarcomas" in patients with testicular germ cell tumors (GCTs) are a common form of "somatic-type malignancy." There is support, based on morphology and immunohistochemistry, that many such sarcomatous tumors represent an unusual form of yolk sac tumor (YST). A virtually universal chromosomal anomaly in GCTs is increase in 12p copy number, often in the form of isochromosome 12p [i(12p)], but this aspect of sarcomatoid YSTs has not hitherto been studied. We performed interphase fluorescent in situ hybridization assay for detection of increased 12p copy number in sarcomatoid YSTs using a bacterial artificial chromosome-derived probe localized to 12p12.1 and a commercially available centromeric probe. Sixteen formalin-fixed, paraffin-embedded specimens from 11 patients, along with normal controls, were studied. Overrepresentation of 12p was expressed as a ratio between the number of signals for 12p and the number of signals for centromere 12. A ratio ≥1.3 was considered overrepresentation. All cases were postchemotherapy recurrences or metastases. Ages ranged 22 to 38 years (mean: 36). Most tumors (12/16) showed myxoid or fibromyxoid stroma and 15 of 16 were high grade. Thirteen of 16 specimens (81%) showed overrepresentation of 12p by the above criteria. Two cases exhibited loss of 12p and 1 case had gain of a whole chromosome 12 (trisomy 12). We conclude that, as in other GCTs, sarcomatous differentiation of YST demonstrates 12p alterations that can be identified by interphase fluorescent in situ hybridization. Apart from 12p overrepresentation, these tumors may exhibit loss of 12p or even gain of an entire chromosome 12 (trisomy 12). Increase in 12p copy number of a sarcomatous neoplasm provides support for sarcomatoid YST in clinically ambiguous settings.

Testicular germ cell tumor: a comprehensive review

Testicular tumors are the most common tumors in adolescent and young men and germ cell tumors (TGCTs) account for most of all testicular cancers. Increasing incidence of TGCTs among males provides strong motivation to understand its biological and genetic basis. Gains of chromosome arm 12p and aneuploidy are nearly universal in TGCTs, but TGCTs have low point mutation rate. It is thought that TGCTs develop from premalignant intratubular germ cell neoplasia that is believed to arise from the failure of normal maturation of gonocytes during fetal or postnatal development. Progression toward invasive TGCTs (seminoma and nonseminoma) then occurs after puberty. Both inherited genetic factors and environmental risk factors emerge as important contributors to TGCT susceptibility. Genome-wide association studies have so far identified more than 30 risk loci for TGCTs, suggesting that a polygenic model fits better with the genetic landscape of the disease. Despite high cure rates because of its particular sensitivity to platinum-based chemotherapy, exploration of mechanisms underlying the occurrence, progression, metastasis, recurrence, chemotherapeutic resistance, early diagnosis and optional clinical therapeutics without long-term side effects are urgently needed to reduce the cancer burden in this underserved age group. Herein, we present an up-to-date review on clinical challenges, origin and progression, risk factors, TGCT mouse models, serum diagnostic markers, resistance mechanisms, miRNA regulation, and database resources of TGCTs. We appeal that more attention should be paid to the basic research and clinical diagnosis and treatment of TGCTs.

Intratumoral heterogeneity and chemoresistance in nonseminomatous germ cell tumor of the testis

BACKGROUND

Nonseminomatous germ cell tumor of the testis (NSGCT) is largely curable. However, a small group of patients develop refractory disease. We investigated the hypothesis that intratumoral heterogeneity contributes to the emergence of chemoresistance and the development of refractory tumor subtypes.

RESULTS

Our institution's records for January 2000 through December 2010 included 275 patients whose primary tumor showed pure embryonal carcinoma (pure E); mixed embryonal carcinoma, yolk sac tumor, and teratoma (EYT); or mixed embryonal carcinoma, yolk sac tumor, seminoma, and teratoma (EYST). Patients with EYST had the highest cancer-specific mortality rate (P = .001). They tended to undergo somatic transformation (P = .0007). Two of 5 patients with clinical stage I EYST who had developed recurrence during active surveillance died of their disease.

MATERIALS AND METHODS

In this retrospective study, we evaluated consecutive patients who had been diagnosed with the three most common histological phenotypes of NSGCT. Chemoresistance was defined as the presence of teratoma, viable germ cell tumor, or somatic transformation in the residual tumor or the development of progressive or relapsed disease after chemotherapy. In a separate prospective study, we performed next-generation sequencing on tumor samples from 39 patients to identify any actionable genetic mutations.

CONCLUSIONS

Our data suggest that patients with EYST in their primary tumor may harbor a potentially refractory NSGCT phenotype and are at increased risk of dying from disease. Despite intratumoral heterogeneity, improved patient selection and personalized care of distinct tumor subtypes may optimize the clinical outcome of patients with NSGCT.

Tumors of the Testis: Morphologic Features and Molecular Alterations

This article reviews the most frequently encountered tumor of the testis; pure and mixed malignant testicular germ cell tumors (TGCT), with emphasis on adult (postpubertal) TGCTs and their differential diagnoses. We additionally review TGCT in the postchemotherapy setting, and findings to be integrated into the surgical pathology report, including staging of testicular tumors and other problematic issues. The clinical features, gross pathologic findings, key histologic features, common differential diagnoses, the use of immunohistochemistry, and molecular alterations in TGCTs are discussed.

Intratumoral heterogeneity: Role of differentiation in a potentially lethal phenotype of testicular cancer

BACKGROUND

Intratumoral heterogeneity presents a major obstacle to the widespread implementation of precision medicine. The authors assessed the origin of intratumoral heterogeneity in nonseminomatous germ cell tumor of the testis (NSGCT) and identified distinct tumor subtypes and a potentially lethal phenotype.

METHODS

In this retrospective study, all consecutive patients who had been diagnosed with an NSGCT between January 2000 and December 2010 were evaluated. The histologic makeup of primary tumors and the clinical course of disease were determined for each patient. A Fine and Gray proportional hazards regression analysis was used to determine the prognostic risk factors, and the Gray test was used to detect differences in the cumulative incidence of cancer death. In a separate prospective study, next‐generation sequencing was performed on tumor samples from 9 patients to identify any actionable mutations.

RESULTS

Six hundred fifteen patients were included in this study. Multivariate analysis revealed that the presence of yolk sac tumor in the primary tumor (P = .0003) was associated with an unfavorable prognosis. NSGCT could be divided into 5 subgroups. Patients in the yolk sac‐seminoma subgroup had the poorest clinical outcome (P = .0015). These tumors tended to undergo somatic transformation (P < .0001). Among the 9 NSGCTs that had a yolk sac tumor phenotype, no consistent gene mutation was detected.

CONCLUSIONS

The current data suggest that intratumoral heterogeneity is caused in part by differentiation of pluripotent progenitor cells. Integrated or multimodal therapy may be effective at addressing intratumoral heterogeneity and treating distinct subtypes as well as a potentially lethal phenotype of NSGCT. Cancer 2016;122:1836–43. © 2016 The Authors. Cancer published by Wiley Periodicals, Inc. on behalf of American Cancer Society. This is an open access article under the terms of the Creative Commons Attribution‐NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.

Whether intratumoral heterogeneity is derived from differentiation of aberrant progenitor cells or from mutation of driver genes is investigated in a relevant clinical model, and the results suggest that intratumoral heterogeneity is caused in part by differentiation of pluripotent progenitor cells. Integrated or multimodal therapy may be effective at addressing intratumoral heterogeneity and treating distinct tumor subtypes as well as potentially lethal tumor phenotypes; this finding has profound clinical implications regarding the origin of intratumoral heterogeneity and the implementation of precision medicine in testicular cancer and other solid tumors.

Fatty acid synthase overexpression in adult testicular germ cell tumors: potential role in the progression of non-seminomatous germ cell tumors

Overexpression of fatty acid synthase (FASN), which is a key enzyme responsible for the endogenous synthesis of fatty acids, and its association with multistep progression have been demonstrated in various human malignant tumors. We aimed to clarify the potential role of FASN overexpression in the development and progression of adult testicular germ cell tumors (TGCTs). From the primary sites of a cohort of 113 TGCT cases, we obtained 221 histological components: 53 intratubular germ cell neoplasias, unclassified (IGCNUs), 84 seminomas, 32 embryonal carcinomas, seven choriocarcinomas, 21 yolk sac tumors, and 24 teratomas. Samples were analyzed for overexpression of FASN by immunohistochemistry. Intensities of immunoreactivity and the fraction of positive cells were classified into each four categories (intensity, 0 to 3; fraction, 0-10 % = 1, 11-50 % = 2, 51-80 % = 3, and >80 % = 4). The overall score was determined by multiplication of both scores and overall scores greater than 6 were considered FASN overexpression. On a component basis, FASN overexpression was detected in 8 % of seminomas but not in IGCNUs (0 %) and was detected frequently in non-seminomatous germ cell tumors (NSGCTs) (88 % of embryonal carcinomas, all choriocarcinomas, 81 % of yolk sac tumors, and 54 % of teratomas). There were no cases of a mixed tumor (i.e., a tumor with multiple histological components) that overexpressed FASN in seminoma components but not in co-existing NSGCT components, suggesting sequential progression. Our immunohistochemical data suggest that FASN overexpression occurs as a late event during the progression from IGCNUs/seminomas to NSGCTs.

Late relapse of testis cancer

Most relapses of germ-cell tumors occur within 2 years of initial treatment. In 2 % to 4 % of patients, relapse may occur later. The retroperitoneum is the primary site of late relapses, and alpha-fetoprotein is the predominant marker. These tumors are highly resistant to chemotherapy. Surgical resection is the preferred treatment. If the recurrent disease is inoperable, salvage chemotherapy may be instituted, followed by resection of the residual disease.

Laser-assisted microdissection in translational research: theory, technical considerations, and future applications

Molecular profiling already exerts a profound influence on biomedical research and disease management. Microdissection technologies contribute to the molecular profiling of diseases, enabling investigators to probe genetic characteristics and dissect functional physiology within specific cell populations. Laser-capture microdissection (LCM), in particular, permits collation of genetic, epigenetic, and gene expression differences between normal, premalignant, and malignant cell populations. Its selectivity for specific cell populations promises to greatly improve the diagnosis and management of many human diseases. LCM has been extensively used in cancer research, contributing to the understanding of tumor biology by mutation detection, clonality analysis, epigenetic alteration assessment, gene expression profiling, proteomics, and metabolomics. In this review, we focus on LCM applications for DNA, RNA, and protein analysis in specific cell types and on commercially available LCM platforms. These analyses could clinically be used as aids to cancer diagnosis, clinical management, genomic profile studies, and targeted therapy. In this review, we also discuss the technical details of tissue preparation, analytical yields, tissue selection, and selected applications using LCM.

Molecular genetic evidence supporting the neoplastic nature of fibrous stroma in testicular teratoma

Testicular teratoma typically consists of heterogeneous mixtures of diverse epithelial and stromal components. The biological nature and genetic characteristics of the fibrous stroma of testicular teratomas have not been thoroughly investigated. Chromosome 12p abnormalities are the hallmark genetic alterations of germ cell tumors. We studied chromosome 12p abnormalities in the fibrous stroma and other components of pure testicular teratomas from 32 patients using interphase fluorescence in situ hybridization. Overall, 72% (23/32) of pure testicular teratomas had chromosome 12p abnormalities. Isochromosome 12p or 12p overrepresentation independent of isochromosome 12p was detected in the fibrous stroma in 53% (17/32) and 41% (13/32) of cases, respectively. Among the 17 cases positive for isochromosome 12p, 8 (47%) also had 12p overrepresentation. In 31% (10/32) cases, the fibrous stroma showed neither 12p overrepresentation nor isochromosome 12p. Isochromosome 12p and 12p overrepresentation were identified, respectively, in the gastrointestinal-type epithelium of 14/23 (61%) and 15/23 (65%) cases; in the respiratory-type epithelium of 41% (7/17) and 41% (7/17) cases; in the squamous epithelium of 62% (8/13) and 54% (7/13) cases; and in the cartilage of 63% (5/8) and 38% (3/8) cases. Concordant chromosomal 12p abnormalities were observed between the fibrous stroma and epithelial elements of testicular teratomas. Our results indicate that the fibrous stroma of testicular teratomas frequently has genetic abnormalities similar to those of the epithelial components. Concordant chromosome 12p alterations between the fibrous stroma and epithelial elements provide further evidence that both epithelial and fibrous components of teratoma are derived from a common progenitor.

Teratoma with somatic-type malignant components of the testis. A review and an update

Malignant transformation of germ cell tumors into somatic malignancy is uncommon. Its presentation differs from series to series, with 43 % of adult cases identified within the primary tumors and the remainder at the time of relapse or in the metastasis. Patients with stage I disease enjoy an excellent prognosis; whereas in metastatic sites when not completely resectable, the somatic type malignancies suffer a dismal prognosis. Radical surgery is significant for the prospects of cure and is standard chemotherapy for germ cell tumors; a transformation-oriented treatment can be effective for these patients. A deeper understanding of the biology of this phenomenon is essential for clinicians involved in such malignancies in order to permit a better control of the disease.

The clinical and therapeutic implications of cancer stem cell biology

Cancer stem cells (CSCs) have provided new insights into the tumorigenesis and metastatic potential of cancer. The discovery of CSCs has provided many new insights into the complexities of cancer therapy: tumor initiation, treatment resistance, metastasis, recurrence, assessment of prognosis and prediction of clinical course. Recent rapid advances in molecular analysis have contributed to the better understanding of the molecular attributes and pathways that give CSCs their unique attributes. Use of these molecular techniques has facilitated elucidation of specific surface markers and pathways that favor propagation of CSCs - allowing for targeted therapy. Furthermore, it has been discovered that a specific microenvironment, or niche, is essential for the genesis of tumors from CSCs. Therapeutic strategies that alter these microenvironments compromise CSC proliferation and constitute another method of targeted cancer therapy. We review the clinical and therapeutic implications of CSCs, with a focus on treatment resistance and metastasis, and the emerging approaches to target CSCs and their microenvironments in order to attain improved outcomes in cancer. It is noteworthy that CSCs are the only cells capable of sustaining tumorigenesis; however, the cell of origin of cancer, in which tumorigenesis is initiated, may be distinct from CSCs that propagate the tumor.

A Spontaneous Teratocarcinoma in the Testis of a Swiss Albino Mouse

A unilateral non-metastatic embryonal carcinoma and teratoma of the testis was observed in a 12-week-old Swiss Albino mouse at the end of a 28-day repeated dose toxicity study. The teratocarcinoma almost completely replaced the parenchyma of the left testis. The tumor was composed of sheets and rosettes of primitive embryonal cells, anaplastic cells, skeletal muscle tissue, sebaceous gland tissue, keratinized stratified squamous epithelium, and ciliated cuboidal epithelium. The histomorphological characteristics of the tumor were reviewed and presented in this report. To the best of the authors' knowledge, this is the first report of spontaneous teratocarcinoma of testis in the Swiss Albino strain of mice.

Protein overexpression and gene amplification of epidermal growth factor receptor in adult testicular germ cell tumors: potential role in tumor progression

Little is known about the pathologic significance of epidermal growth factor receptor (EGFR) expression in malignant testicular germ cell tumors (TGCTs) in adults. From the primary tumor sites of a cohort of 110 TGCT cases, we obtained 209 histologically distinct components: 53 intratubular germ cell neoplasia unclassified (IGCNU) lesions, 83 seminomas (66 pure-form seminomas and 17 seminoma components in the mixed-form with nonseminomatous TGCTs), 27 embryonal carcinomas, eight choriocarcinomas, 18 yolk sac tumors, and 20 immature teratomas. Samples were analyzed for expression of EGFR protein and EGFR gene amplification by immunohistochemistry and fluorescence in situ hybridization (FISH), respectively. Overexpression of the EGFR protein was detected in 28% of seminomas (27% in the pure-form and 29% in the mixed-form), 11% of embryonal carcinomas, 88% of choriocarcinomas, 44% of yolk sac tumors, and none of the IGCNU lesions or immature teratomas. A higher copy number (≥4 copies per cell) and amplification of the EGFR gene were detected in 20% and 10% of seminomas, 13% and 0% of embryonal carcinomas, 71% and 60% of choriocarcinomas, 15% and 8% of yolk sac tumors, and none of the IGCNU lesions or immature teratomas, respectively. Both higher copy number and amplification of the EGFR gene were positively correlated with immunohistochemical overexpression of EGFR protein (each P < 0.0001). These results suggest that overexpression of EGFR protein and increased copy number or amplification of the EGFR gene occur relatively frequently in primary TGCTs, and may play roles in the formation of invasive cancer and in the progression, especially morphological evolution, of tumors.

Allelic loss of the PTEN gene and mutation of the TP53 gene in choriocarcinoma arising from gastric adenocarcinoma: analysis of loss of heterozygosity in two male patients with extragonadal choriocarcinoma

A tumor suppressor gene at 10q23.3, designated PTEN, encoding a dual-specificity phosphatase with lipid and protein phosphatase activity, has been shown to play an essential role in the pathogenesis of a variety of human cancers. Frequent mutations and deletions of PTEN genes are found in cancer. Little is known, however, about the role that PTEN plays in the pathogenesis of a primary choriocarcinoma derived from gastric adenocarcinoma, an extremely rare choriocarcinoma, or in extragonadal retroperitoneal choriocarcinoma. In this study, genetic alterations occurring in extragonadal choriocarcinoma in two Japanese male patients were examined. Loss of heterozygosity (LOH) analysis using a polymorphic marker of the PTEN gene, IVS4+109ins/delTCTTA, revealed a hemizygous deletion of PTEN not only in the primary gastric choriocarcinoma, but also in the gastric adenocarcinoma. Microsatellite marker D12S1051 likewise showed LOH in both the primary gastric choriocarcinoma and the gastric adenocarcinoma. Mutational analysis of the TP53 gene revealed a point mutation in exon 5 (A536G), which resulted in H179R in the gastric choriocarcinoma but not in the gastric adenocarcinoma. No LOH was found for PTEN in an extragonadal retroperitoneal choriocarcinoma. Microsatellite marker D9S162 showed LOH in the extragonadal retroperitoneal choriocarcinoma, but not in the primary gastric choriocarcinoma. These results indicate that LOH of the PTEN gene and of D12S1051 is the molecular pathogenesis of the gastric adenocarcinoma, and the mutation of the TP53 gene is an additional hit for the oncogenesis of choriocarcinoma arising from gastric adenocarcinoma. However, LOH of the PTEN gene is not a common molecular event for pathogenesis of extragonadal choriocarcinoma. In addition, it was found that expression of PTEN is significantly decreased in the nuclei of syncytiotrophoblast-like cancer cells, compared with those of cytotrophoblast-like cancer cells in choriocarcinoma.

Evidence for common clonal origin of multifocal lung cancers

BACKGROUND

Lung cancer is the most common cause of cancer death in the United States. Multiple anatomically separate but histologically similar lung tumors are often found in the same patient. The clonal origin of multiple lung tumors is uncertain.

METHODS

We analyzed 70 lung tumors from 30 patients (23 females and seven males) who underwent surgical resection for lung epithelial tumors, of whom 26 had non-small cell carcinomas and four had carcinoid/atypical carcinoid tumors. All patients had multiple tumors (two to five) involving one or both lungs. Genomic DNA was extracted from paraffin-embedded tissue sections using laser capture microdissection and analyzed for loss of heterozygosity, TP53 mutations, and X-chromosome inactivation status. The percentage (95% confidence interval [CI]) of patients in whom there were concordant patterns of genetic alteration was calculated.

RESULTS

All 30 case subjects showed loss of heterozygosity (LOH) in at least one and at most four of the six polymorphic microsatellite markers. Completely concordant LOH patterns between synchronous and metachronous cancers in individual patients were seen in 26 (87%) of 30 informative patients (95% CI = 75% to 99%). Identical point mutations were present in eight of 10 patients who exhibited TP53 mutation by sequencing. Tumors in 18 (78%) of 23 female patients (95% CI = 67% to 98%) showed identical X-chromosome inactivation patterns. Combining the results of LOH studies, TP53 mutation screening analyses, and X-chromosome inactivation data, we demonstrated that the multiple separate tumors in 23 (77%) of 30 patients (95% CI = 62% to 92%) had identical genetic changes, consistent with monoclonal origin of the separate tumors.

CONCLUSIONS

Our data indicate that the great majority of multifocal lung cancers have a common clonal origin and that multifocality in lung cancer represents local and regional intrapulmonary metastasis.

Benign and Malignant Neoplasms of the Testis and Paratesticular Tissue

Benign and malignant tumors of the testes and paratesticular tissues present an interesting spectrum of diagnostic entities often encountered in routine surgical pathology practice. Germ cell tumors are the most common tumors of the testes and, despite a rising incidence, have excellent prognosis because of their radiosensitivity and/or effective chemotherapeutic agents. The proper classification of these tumors aids in the choice of appropriate treatment options. This article reviews benign and malignant neoplastic entities of the testes and paratesticular tissues and illustrates the classic pathologic characteristics. The differential diagnosis, along with ancillary studies, clinical significance, and presentation are discussed also.

Application of laser-capture microdissection to analysis of gene expression in the testis

The isolation and molecular analysis of highly purified cell populations from complex, heterogeneous tissues has been a challenge for many years. Spermatogenesis in the testis is a particularly difficult process to study given the unique multiple cellular associations within the seminiferous epithelium, making the isolation of specific cell types difficult. Laser-capture microdissection (LCM) is a recently developed technique that enables the isolation of individual cell populations from complex tissues. This technology has enhanced our ability to directly examine gene expression in enriched testicular cell populations by routine methods of gene expression analysis, such as real-time RT-PCR, differential display, and gene microarrays. The application of LCM has however introduced methodological hurdles that have not been encountered with more conventional molecular analyses of whole tissue. In particular, tissue handling (i.e. fixation, storage, and staining), consumables (e.g. slide choice), staining reagents (conventional H&E vs. fluorescence), extraction methods, and downstream applications have all required re-optimisation to facilitate differential gene expression analysis using the small amounts of material obtained using LCM. This review will discuss three critical issues that are essential for successful procurement of cells from testicular tissue sections; tissue morphology, capture success, and maintenance of molecular integrity. The importance of these issues will be discussed with specific reference to the two most commonly used LCM systems; the Arcturus PixCell IIe and PALM systems. The rat testis will be used as a model, and emphasis will be placed on issues of tissue handling, processing, and staining methods, including the application of fluorescence techniques to assist in the identification of cells of interest for the purposes of mRNA expression analysis.

Laser capture microdissection in the genomic and proteomic era: targeting the genetic basis of cancer

The advent of new technologies has enabled deeper insight into processes at subcellular levels, which will ultimately improve diagnostic procedures and patient outcome. Thanks to cell enrichment methods, it is now possible to study cells in their native environment. This has greatly contributed to a rapid growth in several areas, such as gene expression analysis, proteomics, and metabolonomics. Laser capture microdissection (LCM) as a method of procuring subpopulations of cells under direct visual inspection is playing an important role in these areas. This review provides an overview of existing LCM technology and its downstream applications in genomics, proteomics, diagnostics and therapy.

Molecular genetic evidence supporting the neoplastic nature of stromal cells in 'fibrosis' after chemotherapy for testicular germ cell tumours

A residual retroperitoneal mass containing only fibrosis and necrosis is present in 40-52% of patients with advanced testicular germ cell tumours after chemotherapy. The biological nature and genetic characteristics of the stromal cells in these residual masses have not been adequately investigated. Laser-microdissected stromal cells from 27 patients who underwent retroperitoneal lymph node dissection after chemotherapy for metastatic testicular germ cell tumour were analysed. Allelic loss in the stromal cells of fibrosis was present at one or more of the ten microsatellite DNA loci examined in 23 (85%) of the cases. Chromosome arm 12p anomalies, the hallmark of germ cell neoplasia, were present in nine (33%) cases. The high frequency of allelic losses and chromosome arm 12p anomalies in the stromal cells from residual retroperitoneal fibrous masses after chemotherapy for testicular germ cell tumours suggests that the stromal cells are derived from the same tumour progenitor cells as the pre-existing metastatic germ cell tumour.

Molecular genetic evidence supporting the neoplastic nature of the Leydig cell component of ovarian Sertoli-Leydig cell tumors

Sertoli-Leydig cell tumors (SLCT) comprise less than 1% of ovarian tumors. The nature of the Leydig cells has been a subject of controversy and it is unclear whether they are clonally related to the neoplasm or instead proliferate as a non-neoplastic response to the Sertoli-cell component. Twelve ovarian SLCT were identified and hematoxylin and eosin and unstained sections were prepared from formalin-fixed, paraffin-embedded tissue blocks. Tissue samples were microdissected from normal tissue, the Sertoli cell component, and the Leydig cell tumor component using the laser capture microdissection method. If present, tissue was also obtained from any heterologous component. Genomic DNA was extracted from the samples and polymerase chain reaction was used to amplify polymorphic sites at 5 loci: D16S402, TP53, IFNA, D17S855, and D11S1318. X-chromosome inactivation (HUMARA) analysis was also performed. LOH and/or nonrandom X-chromosome inactivation was observed in at least 1 of the 6 amplified loci in the Leydig cell component of 10 of the 12 tumors. LOH and nonrandom X-chromosome inactivation patterns of the Sertoli cell component and Leydig cell component were compared. Concordant allelic loss and/or matching X-chromosome inactivation patterns were observed in 8 (67%) of the 12 tumors. In 7 of these tumors similar LOH or X-chromosome inactivation was observed at 1 site. In 1 tumor similar LOH and/or X-chromosome inactivation was observed at 2 sites. Three tumors had heterologous components. The heterologous components similarly shared LOH/X-chromosome inactivation with the Sertoli cell components at 1 site in 1 case and 2 sites in 2 cases. These data suggest that, at least in some cases, the Leydig cell component of SLCT is neoplastic rather than reactive in nature, and shares a common clonal origin with the coexisting Sertoli cell component. Similarly, the heterologous components, when present, appear to share clonal origin with the Sertoli cell components.

Molecular Genetic Evidence of an Independent Origin of Serous Low Malignant Potential Implants and Lymph Node Inclusions

Patients with ovarian serous tumors of low malignant potential (LMP) are commonly found to have peritoneal implants. Less commonly, similar lesions are seen in lymph nodes, sometimes in association with endosalpingiosis. We compared these lesions to the coexisting ovarian LMP tumors to determine whether they are clonally related to the ovarian neoplasm. Seventeen patients with serous LMP tumors present at 2 or more sites were identified. Tissue samples were microdissected from formalin-fixed paraffin-embedded tissue blocks. Samples of normal tissue, the ovarian LMP tumors, peritoneal LMP implants, and LMP inclusions within lymph nodes were obtained. Genomic DNA was extracted from the samples, and polymerase chain reaction and X-chromosome inactivation (human androgen receptor assay) analysis were performed. The pattern of X-chromosome inactivation could be determined in 15 of the 17 cases, and nonrandom X-chromosome inactivation was observed in 13 of these cases. Twelve of these cases included both ovarian and extraovarian LMP tumors. In 9 of these 12 cases, the extraovarian LMP tumor shared a similar pattern of nonrandom X-chromosome inactivation with the ovarian tumor. In these cases, the shared inactivation pattern was seen at 1 extraovarian site (3 cases), 2 extraovarian sites (4 cases), 5 extraovarian sites (1 case), and 7 of 8 extraovarian sites (1 case). In the remaining 3 cases, opposite patterns of nonrandom X-chromosome inactivation were seen. These data suggest that, in most cases, serous LMP tumor implants and lymph node inclusions share a common clonal origin with the associated ovarian tumors. However, in at least some cases, the implants and inclusions seem to arise independently from the associated ovarian serous LMP tumors.

Loss of Heterozygosity Analysis Identifies Genetic Abnormalities in Mycosis Fungoides and Specific Loci Associated With Disease Progression

Mycosis fungoides (MF) exhibits a variety of underlying molecular defects. Loss of heterozygosity (LOH) is a technique used to detect chromosomal imbalances in neoplastic disorders using archival tissue. We analyzed skin biopsies of MF in different stages for the presence of LOH at specific loci to evaluate underlying genetic aberrations involved in MF and its progression. Twenty-five skin biopsies (15 plaque stage and 10 tumor stage) from 19 patients were evaluated. LOH was examined at 1p22 (D1S2766), 9p21 [IFNA, p15 (D9S1748), p16 (D9S171)], 10q23 [PTEN (D10S185, D10S541, D10S2491)], and 17p13 [p53 (TP53)]. Abnormal lymphocytes were microdissected from formalin-fixed, paraffin-embedded tissue sections. Sixteen of the 25 (64%) specimens evaluated had at least one abnormal LOH locus and LOH was identified in 7 of 15 (47%) plaque and in 9 of 10 (90%) tumor stage lesions, respectively. All 3 patients with sequential biopsies (plaque followed by tumor lesions) had additional LOH abnormalities in tumor specimens compared with plaque stage lesions. LOH most frequently involved chromosome 10, including 7 of 10 (70%) tumor stage lesions. Loss of multiple alleles was only identified in tumor stage cases, with 3 tumors undergoing allelic losses at 3 separate loci. Our results suggest that LOH studies are a robust method for evaluating genetic abnormalities in MF. Tumor stage lesions manifest increasing allelic losses compared with plaque stage. Further, in this series, several loci associated with the tumor suppressor gene PTEN on chromosome 10 appear to be associated with progression from plaque to tumor stage.

Genetically heterogeneous and clonally unrelated metastases may arise in patients with cutaneous melanoma

Melanoma of the skin frequently metastasizes to multiple regional lymph nodes and to distant sites. It is uncertain whether all metastases originate from the same tumor clone or whether the genetic heterogeneity of the primary tumor is reflected in the multiple metastases. A total of 73 archival, formalin-fixed, paraffin-embedded, melanoma lesions, including 13 primary tumors and 60 metastases, were studied from 13 patients each having 2 or more metastatic tumors. Genomic DNA samples were prepared from tissue sections using laser-assisted microdissection. We find that the majority of melanoma metastases share a common clonal origin with the matched primary tumor. However, significant genetic divergence occurs frequently during the clonal evolution of metastatic melanoma. In addition, using X-chromosome inactivation analysis, we find that, in some cases, multiple coexisting metastases seem to be derived from different, genetically unrelated tumor clones, implying that some primary tumors may arise from more than a single transformed melanocyte.

Clonal relationships between epidermotropic metastatic melanomas and their primary lesions: a loss of heterozygosity and X-chromosome inactivation-based analysis

Loss of heterozygosity (LOH) has previously been demonstrated at multiple chromosome microsatellites in primary and metastatic melanomas. Epidermotropic metastases of melanoma are unique in their varied histopathologic appearance, which can mimic a primary lesion. Our objective was to compare LOH profiles in primary and epidermotropic metastatic melanoma to delineate their clonal relationship. We examined the pattern of allelic loss in the primary melanomas of nine patients in addition to the 21 corresponding epidermotropic metastatic melanomas (average 2.3 metastases per patient). DNA samples were prepared from formalin-fixed, paraffin-embedded tissue sections using laser capture microdissection. Eight DNA microsatellite markers on six different chromosomes were analyzed: D1S214 (1p), D6S305 (6q), D9S171 (9p), D9S157 (9p), IFNA (9p), D10S212 (10q), D11S258 (11q), D18S70 (18q). In addition, X-chromosome inactivation analysis was performed in tumors from four women. LOH was seen in 67% (6/9) of primary melanomas and 81% (17/21) of epidermotropic metastatic melanomas. The most frequent allelic losses in informative cases occurred at 10q (33%), 9p (22%), and 11q (22%) in primary melanomas, and at 10q (50%), 1p (44%), and 6q (39%) in epidermotropic metastatic melanomas. Primary lesions demonstrating LOH had concordant allelic loss in at least one locus in a corresponding epidermotropic metastatic melanoma in 83% (5/6) of cases. X-chromosome analysis showed nonrandom inactivation in 75% (3/4) and 71% (5/7) of primary melanoma and epidermotropic metastatic melanoma cases, respectively. Our LOH and X-chromosome inactivation analysis data suggest that epidermotropically metastatic melanomas are clonally related to their primary lesion in many cases. Our data also indicated that some cases diagnosed as epidermotropic metastatic melanoma might be divergent clones or new primaries rather than metastatic disease.

Clonal analysis of human embryonic stem cell differentiation into teratomas

Differentiation of human embryonic stem cells (HESCs) can be studied in vivo through the induction of teratomas in immune-deficient mice. Cells within the teratomas differentiate into all three embryonic germ layers. However, the exact nature of the proliferation and differentiation of HESCs within the teratoma is not fully characterized, and it is not clear whether the differentiation is cell autonomous or affected by neighboring cells. Here, we establish a genetic approach to study the clonality of differentiation in teratomas using a mixture of HESC lines. We first demonstrate, by means of 5-bromo-2'-deoxyuridine incorporation, that cell proliferation occurs throughout the teratoma, and that there are no clusters of undifferentiated-proliferating cells. Using a combination of laser capture microdissection and DNA fingerprinting analysis, we show that different cell lines contribute mutually to the same distinctive tissue structures. Further support for the nonclonal differentiation within the teratoma was achieved by fluorescence in situ hybridization analysis of sex chromosomes. We therefore suggest that in vivo differentiation of HESCs is polyclonal and, thus, may not be cell autonomous, stressing the need for a three-dimensional growth in order to achieve complex differentiation of HESCs. Disclosure of potential conflicts of interest is found at the end of this article.

Glypican 3: a novel marker in testicular germ cell tumors

Glypican 3 (GPC3), a membrane-bound heparin sulfate proteoglycan, may play a role in promoting embryonic cell growth and differentiation. GPC3 is mutated in Simpson-Golabi-Behmel syndrome, characterized by tissue overgrowth and an increased risk of embryonal malignancies. Recently, GPC3 was reported to be one of the over-expressed genes in testicular yolk sac tumors by gene expression microarray analysis. However, the presence of the GPC3 protein in germ cell tumors has never been investigated. The purpose of the study was to investigate the GPC3 expression in various histologic components of testicular germ cell tumors using immunohistochemistry and to assess its possible utility as a diagnostic marker. Tumors from 71 patients were examined, including components of 42 seminomas, 37 embryonal carcinomas, 24 yolk sac tumors, 20 teratomas with mature elements, 16 teratomas with immature elements, and 7 choriocarcinomas. Cytoplasmic and membranous immunoreactivity was semiquantitatively evaluated. All yolk sac tumor (24/24) and choriocarcinoma (7/7) components were immunoreactive for GPC3, whereas only 38% of teratomas with immature elements and 8% of embryonal carcinomas expressed GPC3. There was no immunoreactivity in benign testicular tissue, intratubular germ cell neoplasia, seminomas (0/42), or teratomas with mature elements (0/20). We conclude that the oncofetal protein GPC3 is a novel immunohistochemical marker in testicular germ cell tumors with differential expression in defined histologic subtypes. Our findings suggest a possible role of GPC3 in tumor cell differentiation. Furthermore, GPC immunostaining may be useful in the pathologic diagnosis of nonseminomatous germ cell tumors, particularly yolk sac tumor, and choriocarcinoma.

Inverted papilloma of the urinary bladder: a molecular genetic appraisal

Inverted papilloma of urinary bladder is an uncommon urothelial neoplasm. Its relationship to urothelial carcinoma is controversial. Little is known of the genetic abnormalities of inverted papilloma. To better understand its genetics, we analyzed 39 inverted papillomas, including 36 from men and three from women, for loss of heterozygosity (LOH). We examined four polymorphic microsatellite markers located on chromosome 9q32-33(D9S177), chromosome 9p22 (IFNA), chromosome 3p14.2 (D3S1300) and chromosome 17p13.1 (TP53), where genetic alterations occur frequently in urothelial carcinomas. Additionally, the status of inactivation of X-chromosome was examined in three female patients. The frequency of LOH in informative cases was 8% (3 of 37) for D9S177, 10% (4 of 38) for TP53, 8% (3 of 37) for IFNA and 8% (3 of 36) for D3S1300. In the analysis of X-chromosome inactivation, all three cases yielded informative results and one had nonrandom inactivation of X-chromosomes. The monoclonal origin demonstrated in the study of X-chromosome inactivation indicates the clonal process of inverted papilloma; however, the low incidence of LOH supports the view that inverted papilloma in urinary bladder is a benign neoplasm with molecular genetic abnormalities different from those of urothelial carcinoma.

Clonal Origin of Metastatic Testicular Teratomas

PURPOSE

Testicular teratomas in adult patients are histologically diverse tumors that frequently coexist with other germ cell tumor (GCT) components. These mixed GCTs often metastasize to retroperitoneal lymph nodes where multiple GCT elements are frequently present in the same metastatic lesion. Neither the genetic relationships among the different components in metastatic lesions nor the relationships between primary and metastatic GCT components have been elucidated.

EXPERIMENTAL DESIGN

We examined metastases from 31 patients who underwent primary retroperitoneal lymph node dissection for metastatic testicular GCT. All patients had metastatic mature teratoma with one or more other GCT components. This study included a total of 72 metastatic GCT components and 16 primary GCT components from 31 patients. Genomic DNA samples from each component were prepared from formalin-fixed, paraffin-embedded tissue sections using laser-assisted microdissection. Loss of heterozygosity (LOH) assays for seven microsatellite polymorphic markers on chromosomes 1p36 (D1S1646), 9p21 (D9S171 and IFNA), 9q21 (D9S303), 13q22-q31 (D13S317), 18q22 (D18S543), and 18q21 (D18S60) were done to assess clonality.

RESULTS

Twenty-nine of 31 (94%) cases showed allelic loss in one or more components of the metastatic GCTs. Twenty-nine of 31 mature teratomas showed allelic loss in at least one of seven microsatellite polymorphic markers analyzed. The frequency of allelic loss in informative cases of metastatic mature teratoma was 27% (8 of 30) with D1S1646, 34% (10 of 29) with D9S171, 37% (10 of 27) with IFNA, 27% (8 of 30) with D9S303, 46% (13 of 28) with D13S317, 26% (7 of 27) with D18S543, and 36% (10 of 28) with D18S60. Completely concordant allelic loss patterns between the mature teratoma and all of the other metastatic GCT components were seen in 26 of 29 cases in which the mature teratoma component showed LOH. Nearly identical allelic loss patterns were seen in the three remaining cases. In six cases analyzed, LOH patterns of each metastatic component were compared with each GCT component of the primary testicular tumor. In all six cases, each primary and metastatic component showed an identical pattern of allelic loss.

CONCLUSION

Our data support the common clonal origin of metastatic mature teratomas with other components of metastatic testicular GCTs and with each component of the primary tumor.

Analysis of ovarian teratomas for isochromosome 12p: evidence supporting a dual histogenetic pathway for teratomatous elements

Teratomas are the most common germ cell tumor (GCT) of the ovary and include several types with a range of clinical behavior. As in testicular teratomas, they may be benign, malignant or a component of a mixed GCT. In the testis, data support separate pathogeneses for prepubertal and postpubertal teratomas, with derivation of the former from a nontransformed germ cell and the latter from differentiation of a nonteratomatous, malignant GCT. The absence of cytogenetic abnormalities (including isochromosome 12p (i(12p)) in mature ovarian teratomas suggests that they may be analogous to prepubertal testicular teratomas, but there are no data regarding genetic changes in the teratomatous components of ovarian mixed GCTs. We therefore studied the teratomatous components of six mixed GCTs of the ovary using fluorescence in situ hybridization (FISH) for i(12p). Six mixed GCTs of the ovary occurred in patients 4-33 years of age; all had teratomatous and yolk sac tumor components and three also contained foci of embryonal carcinoma. Using FISH with 12p telomeric and 12 centromeric probes, five of six (83%) cases had detectable i(12p) in their nonteratomatous components, and four of six (66%) in the teratomatous component. One of the two cases without demonstrable i(12p) in the teratomatous portion of the mixed GCT also did not have identifiable 12p abnormalities in other elements of the mixed GCT. By comparison, five pure, mature ovarian teratomas and three pure, immature ovarian teratomas showed no evidence of either i(12p) or other forms of 12p amplification. These findings support that teratoma in mixed ovarian GCTs has a different pathogenesis compared to pure teratoma of the ovary. Furthermore, the findings of i(12p) in both the teratomatous and nonteratomatous components of ovarian mixed GCTs supports that the teratoma derives from other components, similar to the situation in the testis.

Clonal analysis of palmar fibromatosis: a study whether palmar fibromatosis is a real tumor

BACKGROUND

Palmar fibromatosis that arises in the palmar soft tissue is characterized by infiltrative growth with a tendency toward local recurrence but does not metastasize. This study investigated the clonality of this process in twelve female patients, each with a single lesion, by examining the pattern of X-chromosome inactivation.

METHODS

Hematoxylin and eosin stained sections of formalin-fixed, paraffin-embedded tissues were microdissected by laser capture microdissection to obtain the proliferative spindle cells. Tumor cells were isolated from the sections of rectum adenocarcinoma, and used for positive control. The genomic DNAs was extracted with phenol-chloroform, digested with a methylation-sensitive restriction endonuclease HpaII, and amplified by polymerase chain reaction (PCR), using primers targeted to a highly polymorphic short tandem repeat (STR) of the human androgen receptor gene (HUMARA).

RESULTS

Among the twelve samples, three samples failed amplification, one sample showed homozygosity which was not suitable for further analysis, eight samples were successfully amplified, and showed a random X chromosome inactivation pattern, suggesting polyclonality of these lesions.

CONCLUSION

The current findings suggest that palmar fibromatosis is a reactive proliferation rather than a clonal neoplasm.

Molecular Evidence for Independent Origin of Multifocal Neuroendocrine Tumors of the Enteropancreatic Axis

Neuroendocrine tumors of the enteropancreatic axis are often multifocal. We have investigated whether multifocal intestinal carcinoid tumors and multifocal pancreatic endocrine tumors arise independently or whether they originate from a single clone with subsequent intramural or intrapancreatic spread. Twenty-four cases, including 16 multifocal intestinal carcinoid tumors and eight multifocal pancreatic endocrine tumors, were studied. Genomic DNA samples were prepared from 72 distinct tumor nodules using laser capture microdissection. Loss of heterozygosity (LOH) assays were done using markers for putative tumor suppressor genes located on chromosomes 9p21 (p16), 11q13 (MEN1), 11q23 (SDHD), 16q21, 18q21, and 18q22-23. In addition, X chromosome inactivation analysis was done on the tumors from eight female patients. Twenty-two of 24 (92%) cases showed allelic loss in at least one tumor focus, including 15 of 16 (94%) cases of multifocal carcinoid tumors and 7 of 8 (88%) cases of multifocal pancreatic endocrine tumors. Eleven of 24 (46%) cases exhibited a different LOH pattern for each tumor. Additionally, 9 of 24 (38%) cases showed different LOH patterns among some of the coexisting tumors, whereas other coexisting tumors displayed the same allelic loss pattern. Two of 24 (8%) cases showed the same LOH pattern in every individual tumor. X chromosome inactivation analysis showed a discordant pattern of nonrandom X chromosome inactivation in two of six informative cases and concordant pattern of nonrandom X chromosome inactivation in the four remaining informative cases. Our data suggest that some multifocal neuroendocrine tumors of the enteropancreatic axis arise independently, whereas others originate as a single clone with subsequent local and discontinuous metastasis.

Molecular Evidence for the Same Clonal Origin of Multifocal Papillary Thyroid Carcinomas

PURPOSE

Patients with papillary thyroid carcinoma often have two or more distinct papillary tumors at thyroidectomy. Whether these multifocal papillary lesions are clonally related or whether they arise independently is unknown as previous studies have shown conflicting results. Molecular analysis of microsatellite alterations and X-chromosome inactivation status in separate tumors from the same patient can be used to define the genetic relationships among the multiple coexisting tumors.

EXPERIMENTAL DESIGN

We examined 64 separate tumors from 22 female patients who underwent thyroidectomy for thyroid carcinoma. All patients had multiple and separate papillary carcinomas (range, two to six). Genomic DNA samples were prepared from formalin-fixed, paraffin-embedded tissue sections using laser-capture microdissection. Loss of heterozygosity assays for three microsatellite polymorphic markers for putative tumor suppressor genes on chromosomes 3p25 (D3S1597), 9p21 (D9S161), and 18p11.22-p11 (D18S53) were done. In addition, X-chromosome inactivation analysis was done on the tumors from all patients.

RESULTS

Twenty of 22 (91%) cases showed allelic loss in one or more of the papillary lesions in at least one of the three polymorphic markers analyzed. Concordant allelic loss patterns between coexisting papillary tumors were seen in 20 of 23 (87%) cases. A concordant pattern of nonrandom X-chromosome inactivation in the multiple coexisting papillary lesions was seen in all informative cases.

CONCLUSION

Our data suggest that the multifocal tumors in patients with papillary thyroid carcinoma often arise from the same clone. Thus, intrathryoid metastasis may play an important role in the spread of papillary thyroid carcinoma, a finding that has important therapeutic, diagnostic, and prognostic implications.