Beta-Catenin Alterations in Postchemotherapy Yolk Sac Tumor, Postpubertal-Type With Enteroblastic Features.

Postchemotherapy postpubertal-type yolk sac tumors (YST) with glandular and solid phenotypes are aggressive and commonly resistant to systemic chemotherapy. These neoplasms show morphologic features that significantly overlap with those of somatic carcinomas with "enteroblastic" or "fetal" phenotype (the preferred terminology depends on the site of origin). They often present as late or very late recurrences, and their diagnosis is challenging because they frequently affect patients in an age group at risk for carcinomas of somatic origin. Recently, we incidentally identified examples of postchemotherapy glandular and solid YST with "enteroblastic" phenotypes and nuclear expression of beta-catenin, prompting us to further evaluate the prevalence of this phenomenon. We found nuclear expression of beta-catenin in 10 (29%) of 34 such tumors. A subset of cases with nuclear beta-catenin expression was further analyzed with a DNA sequencing panel (n = 6) and fluorescence in situ hybridization for isochromosome 12p [i(12p); n = 5]. Sequencing identified exon 3 CTNNB1 variants in 3 (50%) of 6 analyzed cases, and fluorescence in situ hybridization was positive for i(12p) in 5 of 5 cases. In conclusion, a significant subset of postchemotherapy YST with glandular or solid architecture and "enteroblastic" phenotype demonstrates beta-catenin alterations, suggesting that activation of Wnt signaling may play a role in the progression of these neoplasms. Moreover, nuclear beta-catenin expression in these tumors represents a potential diagnostic pitfall given that carcinomas of true somatic origin with overlapping morphology may also be positive for this marker.

Carcinoma arising in ileal conduit or orthotopic ileal neobladder reconstruction: A 20-year single institute experience.

CONTEXT: Carcinomas found in urinary diversion specimens are uncommon, particularly new primary tumours. New primary tumours primarily occur when the large intestine is utilised, whereas the occurrence is infrequent with the use of the ileum. These tumours include both the recurrence of primary malignancy or the development of a new primary malignancy originating from the small intestine. DESIGN: A search was performed within the pathology laboratory system to identify cases of malignancies involving ileal conduit/reconstruction from 2002 to 2022. Data on demographics, clinical details, pathology and management was recorded. RESULTS: A total of 13 male patients, with a mean age of 67 years (range = 49-81 years) were included in the study. The initial procedure performed included cystoprostatectomy (n = 10, including one case with right nephroureterectomy) and cystectomy (n = 3, including one case for bladder exstrophy) for initial diagnoses including urothelial carcinoma (n = 11; conventional, 6; sarcomatoid, 1; glandular 1; plasmacytoid, 1; micropapillary, 2) and adenocarcinoma (n = 1). The initial management included radical surgery with neoadjuvant chemotherapy/immunotherapy (n = 1), adjuvant chemotherapy (n = 3), intravesical adjuvant BCG (n = 2) and intravesical adjuvant chemotherapy (n = 1). Malignancies in ileal conduit or orthotopic ileal neobladder included recurrent urothelial carcinoma (n = 10) and new secondary adenocarcinomas (n = 3), which developed as early as 3 months (usually recurrence) and up to 13, 33 and 45 years (new primary malignancy) following primary resection. CONCLUSIONS: Utilising the ileum as conduit/neobladder presents a viable alternative for urinary diversion with a reduced malignancy risk compared to using a segment of the large intestine. However, there remains a potential for malignancy, either tumour recurrence or a new primary malignancy. In our study, tumour recurrence occurred up to 4 years following the initial diagnosis and the development of a new primary malignancy occurred up to 45 years after the initial diagnosis. Consequently, it is crucial to prioritise long-term follow-up for these patients undergoing this procedure.

Genomic analysis of primary epithelial neoplasms of the seminal vesicle identifies a subset of mucinous cystic tumours driven by KRAS mutations.

BACKGROUND: Carcinomas of the seminal vesicle are exceedingly rare, with a limited number of cases described in the literature. Reported cases span a relatively wide morphological spectrum, and their genomic features remain unexplored. DESIGN: In this study, we interrogated five primary epithelial neoplasms of the seminal vesicle using a targeted DNA sequencing platform (OncoPanel, 447 genes). RESULTS: The tumours included one adenocarcinoma with intestinal phenotype presenting after external beam radiation (for prostatic adenocarcinoma), one carcinoma with Müllerian-type clear cell phenotype, two mucinous tumours resembling low-grade mucinous neoplasms of the appendix (LAMN) and one mucinous cystadenoma. The post-radiation mucinous adenocarcinoma had genomic findings consistent with bi-allelic inactivation of TP53, as well as multiple copy-number changes with regional and chromosomal arm-level copy-number losses. The Müllerian-type clear cell carcinoma exhibited a complex copy-number profile with numerous regional and arm-level copy-number changes, as well as focal amplification events, including copy-number gain of 8q and amplification of a region within 20q13. Both low-grade mucinous tumours resembling LAMN harboured hot-spot gain-of-function KRAS variants (p.G12V and p.G13D) as the only genomic alteration. No genomic alterations were detected inthe lesion diagnosed as mucinous cystadenoma. CONCLUSION: Our results suggest that primary low-grade mucinous neoplasms of the seminal vesicle may represent a distinct entity equivalent to appendiceal counterparts, driven by gain-of-function variants of RAS GTPases. The remaining tumours showed genomic features that closely resembled those of neoplasms with comparable phenotypes and/or biological characteristics arising in other sites, suggesting that they could be managed similarly, with special considerations related to their anatomical location.

ß-Catenin alterations in testicular Leydig cell tumour: a immunohistochemical and molecular analysis.

BACKGROUND: Testicular Leydig cell tumours (LCTs) are the most common type of sex cord-stromal tumour in men, representing 1%-3% of all testicular neoplasms. Among testicular sex cord-stromal tumours, CTNNB1 mutations and nuclear expression of ß-catenin have been typically associated with Sertoli cell tumour. Recent genomic analyses have shown that CTNNB1 variants are also identified in a subset of LCTs; however, the frequency and clinicopathologic associations of ß-catenin alterations remain incompletely understood in this tumour type. METHODS: In this study, we evaluated 32 LCTs (five malignant/metastasizing, 27 nonmetastasizing) using ß-catenin immunohistochemistry and DNA sequencing. RESULTS: Immunohistochemistry revealed focal or multifocal nuclear ß-catenin expression in 47% of the tumours. Diffuse nuclear ß-catenin expression (in >50% of the tumour cells) was not detected in any of the cases analysed herein. Comparison of ß-catenin-positive and ß-catenin-negative cases did not show significant differences in the frequency of adverse histopathologic findings or malignant clinical behaviour. DNA sequencing performed de novo on a subset of seven cases revealed the presence of exon 3 CTNNB1 variants in four of them (4/7, 57%), with variant allele frequencies (VAF) ranging from 7 to 33%. Two additional ß-catenin-positive cases that had been sequenced as part of a previous study harboured exon 3 CTNNB1 variants at VAF of 28% and 7%, respectively. CONCLUSION: These results demonstrate that ß-catenin alterations are relatively common in LCT, most likely occurring as subclonal events that are not enriched in cases with aggressive features. Further studies are needed to clarify the oncogenic role of ß-catenin in this tumour type.

Evolution of Testicular Germ Cell Tumors in the Molecular Era With Histogenetic Implications.

The current WHO classification of testicular germ cell tumors is based on the pathogenesis of the tumors driven by different genomic events. The germ cell neoplasia in situ is the precursor lesion for all malignant germ cell tumors. The current understanding of pathogenesis is that the developmental and environmental factors with the erasure of parental genomic imprinting lead to the development of abnormal gonocytes that settle in the "spermatogonial Niche" in seminiferous tubules. The abnormal primordial germ cells in the seminiferous tubules give rise to pre-GCNIS cells under the influence of TPSY and OCT4 genes. The whole genome duplication events give rise to germ cell neoplasia in situ, which further acquires alterations in 12p along with NRAS and KRAS mutations to produce seminoma. A subset of seminomas acquires KIT mutation and does not differentiate further. The remaining KIT-stable seminomas differentiate to nonseminomatous GCTs after obtaining recurrent chromosomal losses, epigenetic modification, and posttranscriptional regulation by multiple genes. Nonseminomatous germ cell tumors also develop directly from differentiated germ cell neoplasia in situ. TP53 pathway with downstream drivers may give rise to somatic-type malignancies of GCT. The GCTs are remarkably sensitive to cisplatin-based combination chemotherapy; however, resistance to cisplatin develops in up to 8% of tumors and appears to be driven by TP53/MDM2 gene mutations. Serum and Plasma miRNAs show promise in diagnosing, managing, and following up on these tumors. The mechanisms underlying the development of most tumors have been elucidated; however, additional studies are required to pinpoint the events directing specific characteristics. Advances in identifying specific molecular markers have been seen recently and may be adopted as gold standards in the future.

Renal epithelioid angiomyolipomas overexpress TFE3 and the TFE3-regulated gene TRIM63 in the absence of TFE3 rearrangement.

Angiomyolipoma (AML) is a neoplasm within the perivascular epithelioid cell tumor family that occurs somewhat frequently in the kidney. Most are indolent and discovered incidentally, with rare tumors demonstrating malignant clinical behavior. A small subset of renal AMLs with epithelioid features are associated with aggressive behavior, and may demonstrate morphologic overlap with renal cell carcinomas (e.g., clear cell renal cell carcinoma (RCC), TFE3-rearranged RCC). Prior studies of spindle cell and epithelioid AMLs have identified rare examples with underlying TFE3 gene fusions. TFE3 protein expression (demonstrated by immunohistochemistry) with no evidence of concurrent TFE3 rearrangements has been reported previously in 4/24 AMLs (17%) (Argani et al. Am J Surg Pathol 34:1395-1406, 2010). Currently, the relationship between TFE3 protein expression, TFE3 fusions, and expression of TFE3-mediated genes remains incompletely understood in renal epithelioid AMLs. We sought to explore these relationships using TFE3 break-apart fluorescence in situ hybridization (FISH) and TRIM63 RNA in situ hybridization (ISH) on epithelioid AMLs with moderate to strong TFE3 expression by immunohistochemistry. RNA sequencing (fusion panel) was performed on two cases with negative FISH results to assess for FISH-cryptic gene fusions. The series comprised five epithelioid AMLs from four patients (three women, one man) aged 13 to 76 years. All were considered positive for TFE3 by immunohistochemistry (2 + /3 + expression). TRIM63 ISH was performed on four specimens from three patients, yielding positive results in 3/3 tumors (100%) that were successfully analyzed. TFE3 break-apart FISH was performed on all samples, demonstrating a TFE3 rearrangement in only 1/4 tumors (25%). RNA sequencing demonstrated the absence of productive TFE3 gene fusions in three tumors with negative break-apart TFE3 FISH results. This study demonstrates that renal epithelioid AMLs overexpress TFE3 and TFE3-mediated genes (TRIM63) even in the absence of TFE3 rearrangements. This finding could be explained by functional upregulation of TFE3 secondary to activation of the mammalian target of rapamycin complex 1 (mTORC1). Expression of TFE3 and TRIM63 in this tumor type represents a potential pitfall, given the morphologic and immunophenotypic overlap between epithelioid AML and TFE3-altered renal cell carcinoma.

Molecular characterization of large cell calcifying sertoli cell tumors: A multi-institutional study of 6 benign and 2 malignant tumors.

Large cell calcifying Sertoli cell tumors (LCCSCTs) are rare testicular tumors, representing <1 % of all testicular neoplasms. Almost 40 % of patients with LCCSCTs will present in the context of the inherited tumor predisposition syndrome, the Carney complex. While most LCCSCTs are benign, 10-20 % have malignant behavior. The aim of our study was to analyze LCCSCTs for novel molecular alterations in addition to PRKAR1A mutations and to identify potential drivers for malignant progression. Eight LCCSCTs diagnosed at two institutions were included. Two patients had the Carney complex confirmed on subsequent genetic testing, and two tumors had several adverse pathological findings. One patient presented with metastatic disease at the time of initial diagnosis. Targeted next-generation sequencing detected PRKAR1A alterations in all cases, with heterozygous PRKAR1A mutations in 5 tumors, germline Carney-complex-associated PRKAR1A mutation in 2 patients, and PRKAR1A fusion in 1 tumor. Additionally, sequencing the metastatic case identified CDKN1B and TERT promoter gene mutations. All tumors showed a low tumoral mutational burden and unremarkable copy number alterations except for frequent LOH of 17q24 encompassing the PRKAR1A locus. RNA expression analysis showed increased expression of several markers including novel PRUNE2, and usual markers like inhibin and calretinin. Our study showed that while LCCSCTs have been reported in the setting of cancer predisposition syndromes, the majority of these tumors occur sporadically. PRKAR1A alterations were present in all cases and appear to be the major driver in LCCSCTs. It remains to be determined whether malignant progression may be caused by additional driver mutations.