Origin and biology of a testicular Wilms' tumor

Reprint of: somatic-type malignancies in testicular germ cell tumors

The development of somatic-type malignancy (SM) in testicular germ cell tumor represents a major challenge in the diagnosis and treatment of testicular cancer. Most SMs are derived from teratoma, and the remainder is associated with yolk sac tumor. They occur more frequently in metastases than in primary testicular tumors. SMs demonstrate a variety of histologic types, including sarcoma, carcinoma, embryonic-type neuroectodermal tumor, nephroblastoma-like tumor, and hematologic malignancy. Sarcoma, particularly rhabdomyosarcoma, accounts for the majority of SMs in the primary testicular tumors, whereas carcinoma, particularly adenocarcinoma, is the most common SM in metastases. Although SMs derived from testicular germ cell tumors mimic their histologic counterparts in other organs with overlapping immunohistochemical profiles, isochromosome 12p is present in most SMs, which can be useful in the differential diagnosis. The presence of SM in the primary testicular tumor may not worsen the outcome, but the development of SM in metastasis is associated with a poor prognosis. Furthermore, somatic-type carcinoma is likely associated with a worse prognosis than somatic-type sarcoma. Although SMs respond poorly to the cisplatin-based chemotherapy, timely surgical resection is an effective treatment for most patients.

Somatic-Type Malignancies in Testicular Germ Cell Tumors

The development of somatic-type malignancy (SM) in testicular germ cell tumor represents a major challenge in the diagnosis and treatment of testicular cancer. Most SMs are derived from teratoma, and the remainder is associated with yolk sac tumor. They occur more frequently in metastases than in primary testicular tumors. SMs demonstrate a variety of histologic types, including sarcoma, carcinoma, embryonic-type neuroectodermal tumor, nephroblastoma-like tumor, and hematologic malignancy. Sarcoma, particularly rhabdomyosarcoma, accounts for the majority of SMs in the primary testicular tumors, whereas carcinoma, particularly adenocarcinoma, is the most common SM in metastases. Although SMs derived from testicular germ cell tumors mimic their histologic counterparts in other organs with overlapping immunohistochemical profiles, isochromosome 12p is present in most SMs, which can be useful in the differential diagnosis. The presence of SM in the primary testicular tumor may not worsen the outcome, but the development of SM in metastasis is associated with a poor prognosis. Furthermore, somatic-type carcinoma is likely associated with a worse prognosis than somatic-type sarcoma. Although SMs respond poorly to the cisplatin-based chemotherapy, timely surgical resection is an effective treatment for most patients.

Extrarenal Anaplastic Wilms Tumor: A Case Report With Genomic Analysis and Tumor Models

Primary extrarenal Wilms tumors are rare neoplasms that are presumed to arise from metanephric or mesonephric remnants outside of the kidney. Their pathogenesis is debated but has not been studied, and there are no reports of genomic descriptions of extrarenal Wilms tumors. We describe a diffusely anaplastic extrarenal Wilms tumor that occurred in the lower abdomen and upper pelvis of a 10-year-old boy. In addition to the clinical, histopathologic, and radiologic features, we describe the cytogenetic changes and exomic profile of the tumor. The tumor showed loss of the tumor suppressor AMER1, loss of chromosome regions 1p, 16q, and 22q, gain of chromosome 8, and loss of function TP53 mutation-findings known to occur in renal Wilms tumors. This is the first description of the exomic profile of a primary extrarenal Wilms tumor. Our data indicate that primary extrarenal Wilms tumors may follow the same pathogenetic pathways that are seen in renal Wilms tumors. Finally, we describe the establishment of first ever tumor models (primary cell line and patient-derived xenograft) from an extrarenal Wilms tumor.

Nephroblastoma Arising in a Primary Testicular Teratoma in a Nonatrophic Testis of a 50-Year-Old Man

Extrarenal nephroblastoma is an extremely rare tumor thought to be related to teratoid tumors of germ cell origin. Because few cases have been reported, no standard method for categorizing and managing these tumors exists. To our knowledge, there have only been 3 adult cases of nephroblastoma arising in a germ cell tumor of testicular origin in a nonatrophic testis, all in men aged 19 to 22 years and with aggressive clinical courses. We report a case of nephroblastoma in a nonatrophic testis, with nephroblastoma being the only non–germ cell component, in an older patient and with a more indolent clinical course that was responsive to localized treatment.

High-resolution genomic profiling of an adult Wilms' tumor: evidence for a pathogenesis distinct from corresponding pediatric tumors

Wilms' tumor (WT), the most common kidney tumor among children, is characterized by a triphasic morphology consisting of blastemal, epithelial, and stromal components. Adult WT is a rare malignancy displaying similar histological features. We here present the first published high-resolution genomic analysis of a mixed-type adult WT. This revealed a more pronounced genetic complexity than usually observed in children with mixed-type WT. The majority of chromosomes displayed uniparental disomies, and microdeletions were present in genes with known importance for tumor formation (LRP1B, FHIT, and WWOX) or organogenesis (NEGR1 and ZFPM2), abnormalities not previously reported for pediatric WT. Our results indicate that adult WT is a biological entity distinct from the corresponding pediatric tumor type.

Dissecting the molecular pathways of (testicular) germ cell tumour pathogenesis; from initiation to treatment-resistance

Human type II germ cell tumours (GCTs) originate from an embryonic germ cell, either as a primordial germ cell or gonocyte. This start determines the biological as well as clinical characteristics of this type of cancer, amongst others their totipotency as well as their overall (exceptional) sensitivity to DNA damaging agents. The histology of the precursor lesion, either carcinoma in situ or gonadoblastoma, depends on the level of testicularization (i.e. testis formation) of the gonad. The impact of either intrinsic (genetic) - and environmental factors involved in the pathogenesis is demonstrated by disorders of sex development as well as testicular dysgenesis syndrome as risk factors, including cryptorchidism, hypospadias and disturbed fertility as parameters. This knowledge allows identification of individuals at risk for development of this type of cancer, being a population of interest for screening. Factors known to regulate pluripotency during embryogenesis are proven to be of diagnostic value for type II GCTs, including OCT3/4, even applicable for non-invasive screening. In addition, presence of stem cell factor, also known as KITLG, allows distinction between delayed matured germ cells and the earliest stages of malignant transformation. This is of special interest because of the identified association between development of type II GCTs of the testis and a limited number of single nucleotide polymorphisms, including some likely related to KITL. Transition from the precursor lesion to an invasive cancer is associated with gain of the short arm of chromosome 12, in which multiple genes might be involved, including KRAS2 and possibly NANOG (pseudogenes). While most precursor lesions will progress to an invasive cancer, only a limited number of cancers will develop treatment resistance. Putative explanatory mechanisms are identified, including presence of microsatellite instability, BRAF mutations, apoptosis suppression and p21 sub-cellular localization. It remains to be investigated how these different pathways integrate to each other and how informative they are at the patient-individual level. Further understanding will allow development of more targeted treatment, which will benefit quality of life of these young cancer patients.

Adult extrarenal Wilms' tumor mimicking mixed epithelial and stromal tumor in the retroperitoneum: a case report with immunohistochemical study and review of the literature

We report an extremely rare case of adult extrarenal Wilms' tumor (WT) in a 52-year-old woman who presented with fever and abdominal distension. Computed tomography revealed a well-defined mass lesion measuring 15.0 cm in the right retroperitoneum and that was in contact with the right kidney. The mass and kidney were surgically removed. Grossly, the mass was well-defined, measuring 16.3 x 11.0 x 9.8 cm, and appearing grayish-white in color. The border between the mass and the kidney was well-defined. Histologically, the tumor showed a triphasic pattern consisting of stromal, epithelial and blastemal components. The stromal component was predominant in the tumor and consisted both of spindle cells and smooth muscle cells. The epithelial component showed a mature glandular structure. Immunohistochemically, the stromal component was positive for vimentin, smooth muscle actin and desmin. The blastemal component was positive for vimentin, while the epithelial component was positive for cytokeratin (CK) 18, CK7 and vimentin. WT-1 was negative in the all three components, and the Ki-67 proliferation index was low. The postoperative histopathological diagnosis indicated extrarenal WT arising in the retroperitoneum. Although not treated by either chemotherapy or radiation therapy, she was free from disease recurrence for 30 months after surgery. To the best of our knowledge, this report is only the fourth case of adult extrarenal WT arising in the retroperitoneum. Furthermore, the present case showed predominant smooth muscle differentiation and a mature glandular structure, mimicking a mixed epithelial and stromal tumor.

Wilms' tumor arising within a mediastinal teratoma

The majority of Wilms' tumors present in young children as an intraabdominal mass of renal origin. The use of multimodal treatment protocols according to internationally recognized treatment guidelines has resulted in extremely high cure rates even in the setting of advanced disease. By comparison, Wilms' tumors in older patients or Wilms' tumors located entirely outside the kidney are extremely rare. Because of the rarity of these tumors and the lack of established treatment guidelines specific to these lesions, older patients with atypical Wilms' tumors are at risk for under treatment and poorer outcomes. We report the case of an 18-year-old man with a Wilms' tumor arising within a mediastinal teratoma and discuss the management of this extremely rare lesion.

Pure testicular carcinoid associated with intratubular germ cell neoplasia

This case report describes for the first time a case of pure testicular carcinoid pre-aortic lymph node metastases in a 25 year old patient with carcinoid syndrome. The simultaneous occurrence of intratubular germ cell neoplasia in the surrounding testicular tissue was identified by OCT4 and placental-like alkaline phosphatase positivity. This confirmed that the tumour had a germ cell origin in the testis, rather than being a metastasis from an extragenital carcinoid.

Nephroblastoma Arising in a Germ Cell Tumor of Testicular Origin

We report a nephroblastoma arising in a germ cell tumor of testicular origin occurring in a 22-year-old man. Orchiectomy demonstrated a malignant mixed germ cell tumor composed of mature and immature teratoma with nephroblastoma and rhabdomyosarcoma. Following chemotherapy, the patient developed supraclavicular and retroperitoneal lymphadenopathy. Excision demonstrated metastatic teratoma at both sites. No recurrence was noted with 21 months of additional follow-up. Using tissue microdissection and loss of heterozygosity analysis, we investigated the clonality of the mature teratoma, immature teratoma, nephroblastoma, and rhabdomyosarcoma components of the primary tumor and of the metastatic mature teratoma at the two separate distant sites. Nine microsatellite polymorphic makers were used to examine the pattern of allelic loss in both primary and metastatic tumors. Loss of heterozygosity was found in 4 DNA loci, and the same pattern of allelic loss was demonstrated at all 4 loci in all of the different components of the primary tumor and the metastatic mature teratomas, supporting the germ cell tumor origin of the nephroblastoma component. Loss of heterozygosity on chromosome 17p13 (TP53) was detected in metastatic mature teratoma, but not in the primary tumor. Loss of heterozygosity was observed at 11p13, the locus of WT1 inactivation in patients genetically predisposed to nephroblastoma, and this loss may be an important genetic mechanism in nephroblastomatous differentiation of germ cell tumors. These data support a common clonal origin for nephroblastoma and the other germ cell tumor components.

Nephroblastoma-like tumors in patients with testicular germ cell tumors

Nephroblastoma-like tumors (NLTs) developed in metastatic sites in nine men with testicular germ cell tumors (GCTs). These tumors had a characteristic "triphasic" admixture of primitive tubular structures, sometimes with a glomeruloid pattern, blastema and stroma. Skeletal muscle differentiation was apparent in two cases. Specific neuroendocrine markers (synaptophysin and chromogranin A) were negative. All patients were treated by surgical excision. Six patients were alive with no evidence of disease from 4 to 12 years after diagnosis of GCT and NLT. One patient was alive with disease 6 years after diagnosis of GCT and 3 years after diagnosis of NLT. One man who also had metastatic primitive neuroectodermal tumor (PNET) had short survival, and one patient died of postoperative infection. We conclude that patients with testicular GCTs in whom NLTs develop in metastatic sites often experience prolonged survival. Surgical excision appears to be adequate treatment for NLT arising in metastatic testicular GCT in most patients. It is important to distinguish NLTs from PNETs in metastatic GCTs because of the more aggressive course and the frequently fatal outcome of the latter.

Biphasic synovial sarcoma of the peritoneal cavity with t(X;18) demonstrated by reverse transcriptase polymerase chain reaction

A case of a biphasic synovial sarcoma, arising on the inner surface of the anterior abdominal wall of a 13-year-old girl, is reported. Although the tumor showed rather typical histological and immunohistochemical features for synovial sarcoma, its unusual clinical presentation and anatomical location caused diagnostic difficulty, especially with regard to differentiation from a malignant mesothelioma. Applying reverse transcriptase polymerase chain reaction (RT-PCR) analysis, the SYT-SSX2 chimeric gene transcripts that result from the translocation, t(X;18)(p11.2;q11.2), found in most synovial sarcomas could be demonstrated. Thus, this RT-PCR approach is a reliable method for confirming the diagnosis of synovial sarcomas in unusual locations.

Glycolipids of human primary testicular germ cell tumours

The glycolipid content of human non-seminomatous germ cell tumour cell lines correlates with their differentiation lineage. To analyse whether this reflects the situation in primary tumours, we studied five embryonal carcinomas, five yolk sac tumours and nine (mixed) non-seminomas, using thin-layer chromatography and carbohydrate immunostaining. We also analysed the glycolipid content of 19 seminomas to reveal their relationship with non-seminomas. Lactosylceramide (CDH) was detected in all embryonal carcinomas, but in fewer than half of the seminomas. Seminomas and embryonal carcinomas contained globoseries glycolipids, including globotriosylceramide (Gb3), globoside (Gb4), galactosy globoside (Gb5) and sialy1 galactosyl globoside (GL7). The lacto-series glycolipid Le(x) was found in all embryonal carcinomas, but only in one seminoma. Gangliosides GD3 and GT3 were detected in many seminomas, but rarely in embryonal carcinomas. Yolk sac tumours displayed a heterogeneous glycolipid profile. Compared with seminomas and pure embryonal carcinomas, differentiated non-seminomas had reduced levels of globo-series glycolipids, especially Gb3 and Gb5, whereas CDH, Le(x), GD3 and GT3 were found in the majority of cases. Thus, the glycolipid content of non-seminoma cell lines reflects the situation in primary tumours. Globo-series glycolipids are similarly expressed in seminomas and embryonal carcinomas. The expression of Gb3 and Gb5 is reduced in non-seminomas upon differentiation. Le(x) expression in non-seminomas, including embryonal carcinomas, allows discrimination from seminomas. Expression of gangliosides in seminomas might indicate their maturation from ganglioside-negative precursor cells. Reprogramming of these precursors would result in the formation of Le(x)-expressing embryonal carcinomas.

Primary extrarenal Wilms' tumor in the inguinal canal: case report and review of the literature

Inguinal and scrotal Wilms' tumors are extremely rare; only 15 cases have been reported to date. The authors report a case of inguinal Wilms' tumor (stage III), which occurred in a previously healthy 3 1/2-year-old boy who was staged and treated according to currently accepted National Wilms' Tumor Study III criteria. The exact embryological origin of this tumor has not been determined. However, there is evidence that the origin is more primitive than that of intrarenal Wilms' tumor.

Fluorescence in situ hybridization-based approaches for detection of 12p overrepresentation, in particular i(12p), in cell lines of human testicular germ cell tumors of adults

Overrepresentation of the short arm of chromosome 12 is frequently detected in human testicular germ cell tumors of adolescents and adults (TGCT). This overrepresentation mostly results from the formation of an isochromosome: i(12p). Whether the overrepresentation consistently involves the complete 12p arm including the centromere is still unclear. We studied five TGCT-derived cell lines (NT2, 2102Ep, H12.1, NCCIT, and S2), combining conventional chromosome banding, fluorescence in situ hybridization (FISH), and comparative genomic hybridization (CGH) to investigate the suitability of each of these techniques to detect aberrations involving chromosome 12. Karyotyping showed one or more i(12p)s in NT2, 2102Ep, H12.1, and S2. However, FISH with a centromere-specific probe (p alpha 12H8), a 12p "paint" and a 12p11.2--p12.1 region-specific probe yeast artificial chromosome (YAC)#5 and CGH could not confirm the presence of an i(12p) in S2. Additional randomly distributed 12p sequences were detected by FISH in H12.1, NCCIT, and S2. In most of these cases, (a part of) the centromere was included. All overrepresented 12p regions, except for those in S2, showed hybridization with YAC#5. CGH showed increased copy numbers of the complete 12p arm in the cell lines with one or more i(12p)s but no overrepresentation was noted in the cell lines without i(12p). In metaphase spreads, the centromeric block of the i(12p)s differed in size as compared with those of normal chromosomes 12. This was rarely noted in interphase nuclei. A decrease in size of the centromeric block in 2102Ep and H12.1 caused a weak FISH signal, which was difficult to detect, especially in interphase nuclei. The ratio between p alpha 12H8- and YAC#5-derived signals reflected the presence or absence of one or more i(12p)s. Our results indicate that double FISH with a centromere- and a 12p-specific probe can be used to detect 12p overrepresentation [including i(12p)] in TGCT both in metaphase spreads and interphase nuclei. CGH confirmed the relative overrepresentation of 12p sequences as detected by FISH and showed that in these cell lines the complete 12p was involved.