DICER1 mutations in familial pleuropulmonary blastoma

International Society of Paediatric Surgical Oncology (IPSO) Surgical Practice Guidelines

Most children with tumors will require one or more surgical interventions as part of the care and treatment, including making a diagnosis, obtaining adequate venous access, performing a surgical resection for solid tumors (with staging and reconstruction), performing procedures for cancer prevention and its late effects, and managing complications of treatment; all with the goal of improving survival and quality of life. It is important for surgeons to adhere to sound pediatric surgical oncology principles, as they are closely associated with improved local control and survival. Unfortunately, there is a significant disparity in survival rates in low and middle income countries, when compared to those from high income countries. The International Society of Paediatric Surgical Oncology (IPSO) is the leading organization that deals with pediatric surgical oncology worldwide. This organization allows experts in the field from around the globe to gather and address the surgical needs of children with cancer. IPSO has been invited to contribute surgical guidance as part of the World Health Organization Initiative for Childhood Cancer. One of our goals is to provide surgical guidance for different scenarios, including those experienced in High- (HICs) and Low- and Middle-Income Countries (LMICs). With this in mind, the following guidelines have been developed by authors from both HICs and LMICs. These have been further validated by experts with the aim of providing evidence-based information for surgeons who care for children with cancer. We hope that this initiative will benefit children worldwide in the best way possible. Simone Abib, IPSO President Justin T Gerstle, IPSO Education Committee Chair Chan Hon Chui, IPSO Secretary.

Multimodality Imaging of Pleuropulmonary Blastoma: Pearls, Pitfalls, and Differential Diagnosis

Pleuropulmonary blastomas are rare, potentially aggressive embryonal cancers of the lung parenchyma and pleural surfaces that account for 0.25%-0.5% of primary pulmonary malignancies in children. Pleuropulmonary blastomas are classified as cystic (type I), mixed cystic and solid (type II), and solid (type III). Pleuropulmonary blastoma occurs in the same age group (0-6 years) as other more common solid tumors such as neuroblastoma and Wilms tumor. Differential diagnosis includes metastasis from Wilms tumor and macrocystic congenital pulmonary airway malformation (CPAM). A key pathologic and genetic discriminator is the DICER1 germline mutation found in patients with pleuropulmonary blastoma. Imaging, histopathologic, and clinical data are important to use in conjunction in order to determine the diagnosis and risk stratification of pleuropulmonary blastomas. Survival varies from poor to good, depending on type. However, the spectrum of pleuropulmonary blastoma is insufficiently understood due to the variable presentation of this rare disease. We present a current review of the literature regarding pleuropulmonary blastomas in this article.

Genetic context of oncogenic drivers dictates vascular sarcoma development in aP2‐Cre mice

Angiosarcomas are aggressive vascular sarcomas that arise from endothelial cells and have an extremely poor prognosis. Because of the rarity of angiosarcomas, knowledge of molecular drivers and optimized treatment strategies is lacking, highlighting the need for in vivo models to study the disease. Previously, we generated genetically engineered mouse models of angiosarcoma driven by aP2‐Cre‐mediated biallelic loss of Dicer1 or conditional activation of Kras^G12D with Cdkn2a loss that histologically and genetically resemble human tumors. In the present study, we found that DICER1 functions as a potent tumor suppressor and its deletion, in combination with either KRAS^G12D expression or Cdkn2a loss, is associated with angiosarcoma development. Independent of the genetic driver, the mTOR pathway was activated in all murine angiosarcoma models. Direct activation of the mTOR pathway by conditional deletion of Tsc1 with aP2‐Cre resulted in tumors that resemble intermediate grade human kaposiform hemangioendotheliomas, indicating that mTOR activation was not sufficient to drive the malignant angiosarcoma phenotype. Genetic dissection of the spectrum of vascular tumors identified genes specifically regulated in the aggressive murine angiosarcomas that are also enriched in human angiosarcoma. The genetic dissection driving the transition across the malignant spectrum of endothelial sarcomas provides an opportunity to identify key determinants of the malignant phenotype, novel therapies for angiosarcoma, and novel in vivo models to further explore angiosarcoma pathogenesis. © 2022 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

The Multifaceted Profile of Thyroid Disease in the Background of DICER1 Germline and Somatic Mutations: Then, Now and Future Perspectives

DICER1 protein is a member of the ribonuclease (RNAse) III family with a key role in the biogenesis of microRNAs (miRNA) and in microRNA processing, potentially affecting gene regulation at the post-transcriptional level. The role of DICER1 and its relevance to thyroid cellular processes and tumorigenesis have only recently been explored, following the acknowledgement that DICER1 germline and somatic changes can contribute not only to non-toxic multinodule goiter (MNG) lesions detected in individuals of affected families but also to a series of childhood tumours, including thyroid neoplasms, which can be identified from early infancy up until the decade of 40s. In a context of DICER1 germline gene mutation, thyroid lesions have recently been given importance, and they may represent either an index event within a syndromic context or the isolated event that may trigger a deeper and broader genomic analysis screening of individuals and their relatives, thereby preventing the consequences of a late diagnosis of malignancy. Within the syndromic context MNG is typically the most observed lesion. On the other hand, in a DICER1 somatic mutation context, malignant tumours are more common. In this review we describe the role of DICER protein, the genomic events that affect the DICER1 gene and their link to tumorigenesis as well as the frequency and pattern of benign and malignant thyroid lesions and the regulation of DICER1 within the thyroidal environment.

Transnasal endoscopic resection of nasal chondromesenchymal hamartoma in infancy: an analysis of 5 cases

Background

Nasal chondromesenchymal hamartomas (NCMHs) are extremely rare benign tumors that most commonly affect children in the first year of life. The purpose of this study was to investigate and summarize the characteristics of NCMH cases and the efficacy of transnasal endoscopic resection of NCMHs.

Methods

This is a retrospective study including 5 cases of infant diagnosed as NCMH between April 2016 and April 2020. Diagnostic techniques include nasoendoscopy, computerized tomography (CT) scan, magnetic resonance imaging (MRI) with contrast and microscopic and immunohistologic studies. Data collected included patient demographics, patient symptoms, radiographic findings, characteristics of tumor growth, follow-up time, recurrence, and postoperative complications.

Results

In 5 cases, 3 were males and 2 were females who aged 1, 2, 3, 6 months and 1 year, respectively. The size of the mass measured 1.6 cm*1.9 cm*1.8 cm at its smallest and largest was 4.0 cm*3.5 cm*3.0 cm. All five patients underwent tumor resection via transnasal endoscopic approach. Four tumors were completely removed, and one underwent partial resection, which was completely resected by midfacial degloving operation 13 months after the first surgery. There was no postoperative complication. The current postoperative follow-up period was 1 to 4 years, and no recurrence has been observed.

Conclusions

Complete surgical resection of NCHM is necessary to resolve the symptoms and prevent recurrence. Transnasal endoscopic approach is a safe and effective choice for pediatric NCMH patients.

DICER1 tumor predisposition syndrome: an evolving story initiated with the pleuropulmonary blastoma

DICER1 syndrome (OMIM 606241, 601200) is a rare autosomal dominant familial tumor predisposition disorder with a heterozygous DICER1 germline mutation. The most common tumor seen clinically is the pleuropulmonary blastoma (PPB), a lung neoplasm of early childhood which is classified on its morphologic features into four types (IR, I, II and III) with tumor progression over time within the first 4-5 years of life from the prognostically favorable cystic type I to the unfavorable solid type III. Following the initial report of PPB, its association with other cystic neoplasms was demonstrated in family studies. The detection of the germline mutation in DICER1 provided the opportunity to identify and continue to recognize a number seemingly unrelated extrapulmonary neoplasms: Sertoli-Leydig cell tumor, gynandroblastoma, embryonal rhabdomyosarcomas of the cervix and other sites, multinodular goiter, differentiated and poorly differentiated thyroid carcinoma, cervical-thyroid teratoma, cystic nephroma-anaplastic sarcoma of kidney, nasal chondromesenchymal hamartoma, intestinal juvenile-like hamartomatous polyp, ciliary body medulloepithelioma, pituitary blastoma, pineoblastoma, primary central nervous system sarcoma, embryonal tumor with multilayered rosettes-like cerebellar tumor, PPB-like peritoneal sarcoma, DICER1-associated presacral malignant teratoid neoplasm and other non-neoplastic associations. Each of these neoplasms is characterized by a second somatic mutation in DICER1. In this review, we have summarized the salient clinicopathologic aspects of these tumors whose histopathologic features have several overlapping morphologic attributes particularly the primitive mesenchyme often with rhabdomyoblastic and chondroid differentiation and an uncommitted spindle cell pattern. Several of these tumors have an initial cystic stage from which there is progression to a high grade, complex patterned neoplasm. These pathologic findings in the appropriate clinical setting should serve to alert the pathologist to the possibility of a DICER1-associated neoplasm and initiate appropriate testing on the neoplasm and to alert the clinician about the concern for a DICER1 mutation.

Identification of Essential Genes in Caenorhabditis elegans with Lethal Mutations Maintained by Genetic Balancers

Genetic balancer systems, which allow effective capture and maintenance of lethal mutations stably, play an important role in identifying essential genes. Whole-genome sequencing (WGS) followed by bioinformatics analysis, combined with genetic mapping data analysis, allows for an efficient and economical means of identifying genomic mutations in essential genes. Using this approach, we successfully identified 104 essential genes on ChrI, ChrIII, and ChrV in C. elegans. In this report, we described a protocol that sequences the genome of prebalanced Caenorhabditis elegans (C. elegans) strains to carry lethal mutations and identifies candidate causal mutations and candidate essential genes using a robust bioinformatics procedure.

Pituitary Tumors: Genetic and Molecular Factors Underlying Pathogenesis and Clinical Behavior

Pituitary neuroendocrine tumors (PitNETs) are the most common intracranial neoplasms. Although generally benign, they can show a clinically aggressive course, with local invasion, recurrences, and resistance to medical treatment. No universally accepted biomarkers of aggressiveness are available yet, and predicting clinical behavior of PitNETs remains a challenge. In rare cases, the presence of germline mutations in specific genes predisposes to PitNET formation, as part of syndromic diseases or familial isolated pituitary adenomas, and associates to more aggressive, invasive, and drug-resistant tumors. The vast majority of cases is represented by sporadic PitNETs. Somatic mutations in the α subunit of the stimulatory G protein gene (gsp) and in the ubiquitin-specific protease 8 (USP8) gene have been recognized as pathogenetic factors in sporadic GH- and ACTH-secreting PitNETs, respectively, without an association with a worse clinical phenotype. Other molecular factors have been found to significantly affect PitNET drug responsiveness and invasive behavior. These molecules are cytoskeleton and/or scaffold proteins whose alterations prevent proper functioning of the somatostatin and dopamine receptors, targets of medical therapy, or promote the ability of tumor cells to invade surrounding tissues. The aim of the present review is to provide an overview of the genetic and molecular alterations that can contribute to determine PitNET clinical behavior. Understanding subcellular mechanisms underlying pituitary tumorigenesis and PitNET clinical phenotype will hopefully lead to identification of new potential therapeutic targets and new markers predicting the behavior and the response to therapeutic treatments of PitNETs.

Clinicians Practicing Obstetrics and Gynecology Are Uniquely Situated to Recognize DICER1 Syndrome

Pediatric gynecologic malignancies are rare, present with diverse pathologic findings, and can be associated with genetic syndromes such as Peutz-Jeghers, Lynch, and Li-Fraumeni. DICER1 mutation is an emerging entity that has been demonstrated to cause a hereditary tumor predisposition syndrome. Previously, gynecologic manifestations of DICER1 syndrome have been described in single or small case reports with an array of pathologic findings. Here, we discuss pediatric and adolescent patients with gynecologic DICER1-associated tumors, outline the significance of DICER1, and suggest points of care where the syndrome may be diagnosed in the context of routine obstetric and gynecology practice. Patients presenting with a personal or family history suspicious for DICER1 syndrome should undergo both germline and somatic testing, as the presence of DICER1 mutations will have an impact on both treatment and surveillance strategies.

Tumor evolution selectively inactivates the core microRNA machinery for immune evasion

Cancer cells acquire genetic heterogeneity to escape from immune surveillance during tumor evolution, but a systematic approach to distinguish driver from passenger mutations is lacking. Here we investigate the impact of different immune pressure on tumor clonal dynamics and immune evasion mechanism, by combining massive parallel sequencing of immune edited tumors and CRISPR library screens in syngeneic mouse tumor model and co-culture system. We find that the core microRNA (miRNA) biogenesis and targeting machinery maintains the sensitivity of cancer cells to PD-1-independent T cell-mediated cytotoxicity. Genetic inactivation of the machinery or re-introduction of ANKRD52 frequent patient mutations dampens the JAK-STAT-interferon-γ signaling and antigen presentation in cancer cells, largely by abolishing miR-155-targeted silencing of suppressor of cytokine signaling 1 (SOCS1). Expression of each miRNA machinery component strongly correlates with intratumoral T cell infiltration in nearly all human cancer types. Our data indicate that the evolutionarily conserved miRNA pathway can be exploited by cancer cells to escape from T cell-mediated elimination and immunotherapy.

Clinical heterogeneity and reduced penetrance in DICER1 syndrome: a report of three families

INTRODUCTION

DICER1 syndrome is characterized by increased susceptibility to malignancies, mostly occurring in childhood. The range of phenotypic effects of DICER1 variants is under investigation, and the syndrome's phenotypic spectrum is steadily widening. We report on three Italian families showing heterogeneous clinical presentation and reduced penetrance in family members.

CASE DESCRIPTIONS

Patient 1 is a 10-year-old girl with a Sertoli-Leydig cell tumor. Although family history was unremarkable, genetic testing identified a DICER1 germline variant, inherited from her healthy father. Benign thyroid nodules were subsequently diagnosed in both the proband and her father. Patient 2 is an 8-month-old boy with type 1 pleuropulmonary blastoma. His sister developed a nephroblastoma at age 2 years. A DICER1 novel variant was identified in both siblings and their healthy father. Patient 3 is a 22-year-old man who developed a spinal extramedullary intradural mass diagnosed as rhabdomyosarcoma with a peculiar tubular, gland-like component. Tumor testing revealed two pathogenic DICER1 variants, one of which was confirmed to be germline and identified in his 17-year-old healthy brother and in his father, who showed multiple thyroid nodules.

CONCLUSIONS

Among our patients, three developed tumors most frequently associated with DICER1 syndrome (i.e. pleuropulmonary blastoma, nephroblastoma, and Sertoli-Leydig cell tumor). One developed a peculiar sarcoma of the spinal cord not previously described in DICER1 syndrome. Genetic testing in relatives highlighted the paternal origin and reduced penetrance in all families, with thyroid benign lesions as the most common features in otherwise unaffected individuals.

Thoracic Sertoli-Leydig cell tumor: An alternative type of pleuropulmonary blastoma associated with DICER1 variation

A 2-year-old boy presented with a large cystic and solid chest mass arising from the lung, radiographically consistent with pleuropulmonary blastoma (PPB). He underwent right lower lobectomy with resection of a well-circumscribed, mixed solid and cystic mass. The solid areas were composed of cords and nests of tumor cells in the myxoid stroma and retiform foci whose pathologic and immunophenotypic findings were consistent with a sex cord-stromal tumor with features of a Sertoli-Leydig cell tumor. Tumor testing showed a pathogenic variant in the DICER1 RNase IIIb hotspot domain. Family history was suggestive of DICER1 germline pathogenic DICER1 variation in absence of a detectable germline variant. He received 12 cycles of chemotherapy with ifosfamide, vincristine, dactinomycin and doxorubicin (IVADo) and surgery with complete response. One year after completion of chemotherapy, imaging studies showed concern for recurrence confirmed by thorascopic biopsy of a pleural-based mass. He is currently receiving cisplatin-based chemotherapy with reduction in tumor size. Review of the literature showed no similar cases; however, review of our pathology files revealed a single similar case of anterior mediastinal Sertoli cell tumor in a 3-year-old girl.

Classical and noncanonical functions of miRNAs in cancers

Alterations in microRNAs (miRNAs) expression are causative in the initiation and progression of human cancers. The molecular events responsible for the widespread differential expression of miRNAs in malignancy are exemplified by their location in cancer-associated genomic regions, epigenetic mechanisms, transcriptional dysregulation, chemical modifications and editing, and alterations in miRNA biogenesis proteins. The classical miRNA function is synonymous with post-transcriptional repression of target protein genes. However, several studies have reported miRNAs functioning outside this paradigm and some of these novel modes of regulation of gene expression have been implicated in cancers. Here, we summarize key aspects of miRNA involvement in cancer, with a special focus on these lesser-studied mechanisms of action.

Effect of p53 and its N-terminally truncated isoform, Δ40p53, on breast cancer migration and invasion

Breast cancer is the most diagnosed malignancy in women, with over half a million women dying from this disease each year. In our previous studies, ∆40p53, an N‐terminally truncated p53 isoform, was found to be upregulated in breast cancers, and a high ∆40p53 : p53α ratio was linked with worse disease‐free survival. Although p53α inhibits cancer migration and invasion, little is known about the role of ∆40p53 in regulating these metastasis‐related processes and its role in contributing to worse prognosis. The aim of this study was to assess the role of ∆40p53 in breast cancer migration and invasion. A relationship between Δ40p53 and gene expression profiles was identified in oestrogen‐receptor‐positive breast cancer specimens. To further evaluate the role of Δ40p53 in oestrogen‐receptor‐positive breast cancer, MCF‐7 and ZR75‐1 cell lines were transduced to knockdown p53α or Δ40p53 and overexpress Δ40p53. Proliferation, migration and invasion were assessed in the transduced sublines, and gene expression was assessed through RNA‐sequencing and validated by reverse‐transcription quantitative PCR. Knockdown of both p53α and ∆40p53 resulted in increased proliferation, whereas overexpression of ∆40p53 reduced proliferation rates. p53α knockdown was also associated with increased cell mobility. ∆40p53 overexpression reduced both migratory and invasive properties of the transduced cells. Phenotypic findings are supported by gene expression data, including differential expression of LRG1, HYOU1, UBE2QL1, SERPINA5 and PCDH7. Taken together, these results suggest that, at the basal level, ∆40p53 works similarly to p53α in suppressing cellular mobility and proliferation, although the role of Δ40p53 may be cell context‐specific.

Wilms tumour

Wilms tumour (WT) is a childhood embryonal tumour that is paradigmatic of the intersection between disrupted organogenesis and tumorigenesis. Many WT genes play a critical (non-redundant) role in early nephrogenesis. Improving patient outcomes requires advances in understanding and targeting of the multiple genes and cellular control pathways now identified as active in WT development. Decades of clinical and basic research have helped to gradually optimize clinical care. Curative therapy is achievable in 90% of affected children, even those with disseminated disease, yet survival disparities within and between countries exist and deserve commitment to change. Updated epidemiological studies have also provided novel insights into global incidence variations. Introduction of biology-driven approaches to risk stratification and new drug development has been slower in WT than in other childhood tumours. Current prognostic classification for children with WT is grounded in clinical and pathological findings and in dedicated protocols on molecular alterations. Treatment includes conventional cytotoxic chemotherapy and surgery, and radiation therapy in some cases. Advanced imaging to capture tumour composition, optimizing irradiation techniques to reduce target volumes, and evaluation of newer surgical procedures are key areas for future research.

Emerging Role of isomiRs in Cancer: State of the Art and Recent Advances

The advent of Next Generation Sequencing technologies brought with it the discovery of several microRNA (miRNA) variants of heterogeneous lengths and/or sequences. Initially ascribed to sequencing errors/artifacts, these isoforms, named isomiRs, are now considered non-canonical variants that originate from physiological processes affecting the canonical miRNA biogenesis. To date, accurate IsomiRs abundance, biological activity, and functions are not completely understood; however, the study of isomiR biology is an area of great interest due to their high frequency in the human miRNome, their putative functions in cooperating with the canonical miRNAs, and potential for exhibiting novel functional roles. The discovery of isomiRs highlighted the complexity of the small RNA transcriptional landscape in several diseases, including cancer. In this field, the study of isomiRs could provide further insights into the miRNA biology and its implication in oncogenesis, possibly providing putative new cancer diagnostic, prognostic, and predictive biomarkers as well. In this review, a comprehensive overview of the state of research on isomiRs in different cancer types, including the most common tumors such as breast cancer, colorectal cancer, melanoma, and prostate cancer, as well as in the less frequent tumors, as for example brain tumors and hematological malignancies, will be summarized and discussed.

RNA-binding proteins of COSMIC importance in cancer

Herculean efforts by the Wellcome Sanger Institute, the National Cancer Institute, and the National Human Genome Research Institute to sequence thousands of tumors representing all major cancer types have yielded more than 700 genes that contribute to neoplastic growth when mutated, amplified, or deleted. While some of these genes (now included in the COSMIC Cancer Gene Census) encode proteins previously identified in hypothesis-driven experiments (oncogenic transcription factors, protein kinases, etc.), additional classes of cancer drivers have emerged, perhaps none more surprisingly than RNA-binding proteins (RBPs). Over 40 RBPs responsible for virtually all aspects of RNA metabolism, from synthesis to degradation, are recurrently mutated in cancer, and just over a dozen are considered major cancer drivers. This Review investigates whether and how their RNA-binding activities pertain to their oncogenic functions. Focusing on several well-characterized steps in RNA metabolism, we demonstrate that for virtually all cancer-driving RBPs, RNA processing activities are either abolished (the loss-of-function phenotype) or carried out with low fidelity (the LoFi phenotype). Conceptually, this suggests that in normal cells, RBPs act as gatekeepers maintaining proper RNA metabolism and the "balanced" proteome. From the practical standpoint, at least some LoFi phenotypes create therapeutic vulnerabilities, which are beginning to be exploited in the clinic.

Primary Biphasic Hepatic Sarcoma in DICER1 Syndrome

DICER1 tumor predisposition syndrome is a rare genetic disorder that predisposes individuals to multiple benign and malignant neoplasms. The phenotype is vast and includes pleuropulmonary blastoma (PPB), thyroid nodules, cystic nephroma, Wilms tumor, ovarian Sertoli-Leydig cell tumor, and medulloepithelioma, among others. Herein, we describe a patient with a DICER1 germline pathogenic variant presenting with two neoplasms that are not commonly encountered in the context of DICER1 syndrome. The first tumor is a multiloculated cystic hepatic lesion with a biphasic pattern, composed of cysts lined by bland biliary type (CK19-positive) epithelium surrounded by a condensation of sarcomatous spindled cell proliferation in a myxoid stroma. This neoplasm resembled PPB or cystic nephroma with malignant transformation. The second tumor is a chest nodule consistent with low-grade hidradenocarcinoma. Although it is difficult to speculate with just a single case, these unusual neoplasms occurring in particular at a young age raises the possibility that they can be inherent to, and thus, be part of the DICER1 tumor predisposition syndrome phenotype.

Embryonal rhabdomyosarcoma of the uterine corpus: a clinicopathological and molecular analysis of 21 cases highlighting a frequent association with DICER1 mutations

Herein we evaluated a series of 21 embryonal rhabdomyosarcomas of the uterine corpus (ucERMS), a rare neoplasm, to characterize their morphology, genomics, and behavior. Patients ranged from 27 to 73 (median 52) years and tumors from 4 to 15 (median 9) cm, with extrauterine disease noted in two. Follow-up (median 16 months) was available for 14/21 patients; nine were alive and well, four died of disease, and one died from other causes. Most tumors (16/21) showed predominantly classic morphology, comprised of alternating hyper- and hypocellular areas of primitive small cells and differentiating rhabdomyoblasts in a loose myxoid/edematous stroma. A cambium layer was noted in all; seven had heterologous elements (six with fetal-type cartilage) and eight displayed focal anaplasia. The remaining five neoplasms showed only a minor component (≤20%) of classic morphology, with anaplasia noted in four and tumor cell necrosis in three. The most frequent mutations detected were in DICER1 (14/21), TP53 (7/20), PI3K/AKT/mTOR pathway (7/20), and KRAS/NRAS (5/20). Copy-number alterations were present in 10/19 tumors. Overall, 8/14 DICER1-associated ucERMS showed concurrent loss of function and hotspot mutations in DICER1, which is a feature more likely to be seen in tumors associated with DICER1 syndrome. Germline data were available for two patients, both DICER1 wild type (one with concurrent loss of function and hotspot alterations). DICER1-associated ucERMS were more likely to show a classic histological appearance including heterologous elements than DICER1-independent tumors. No differences in survival were noted between the two groups, but both patients with extrauterine disease at diagnosis and two with recurrences died from disease. As no patients had a known personal or family history of DICER1 syndrome, we favor most DICER1-associated ucERMS to be sporadic.

Recent advances in Wilms' tumor predisposition

Wilms' tumor (WT), the most common childhood kidney cancer, develops in association with an underlying germline predisposition in up to 15% of cases. Germline alterations affecting the WT1 gene and epigenetic alterations affecting the 11p15 locus are associated with a selective increase in WT risk. Nevertheless, WT also occurs in the context of more pleiotropic cancer predispositions, such as DICER1, Li-Fraumeni and Bloom syndrome, as well as Fanconi anemia. Recent germline genomic investigations have increased our understanding of the host genetic factors that influence WT risk, with sequencing of rare familial cases and large WT cohorts revealing an expanding array of predisposition genes and associated genetic conditions. Here, we describe evidence implicating WT1, the 11p15 locus, and the recently identified genes CTR9, REST and TRIM28 in WT predisposition. We discuss the clinical features, mode of inheritance and biological aspects of tumorigenesis, when known. Despite these described associations, many cases of familial WT remain unexplained. Continued investigations are needed to fully elucidate the landscape of germline genetic alterations in children with WT. Establishing a genetic diagnosis is imperative for WT families so that individuals harboring a predisposing germline variant can undergo surveillance, which should enable the early detection of tumors and use of less intensive treatments, thereby leading to improved overall outcomes.

Clinicopathologic and molecular analysis of embryonal rhabdomyosarcoma of the genitourinary tract: evidence for a distinct DICER1-associated subgroup

Embryonal rhabdomyosarcoma (ERMS) of the uterus has recently been shown to frequently harbor DICER1 mutations. Interestingly, only rare cases of extrauterine DICER1-associated ERMS, mostly located in the genitourinary tract, have been reported to date. Our goal was to study clinicopathologic and molecular profiles of DICER1-mutant (DICER1-mut) and DICER1-wild type (DICER1-wt) ERMS in a cohort of genitourinary tumors. We collected a cohort of 17 ERMS including nine uterine (four uterine corpus and five cervix), one vaginal, and seven urinary tract tumors. DNA sequencing revealed mutations of DICER1 in 9/9 uterine ERMS. All other ERMS of our cohort were DICER1-wt. The median age at diagnosis of patients with DICER1-mut and DICER1-wt ERMS was 36 years and 5 years, respectively. Limited follow-up data (available for 15/17 patients) suggested that DICER1-mut ERMS might show a less aggressive clinical course than DICER1-wt ERMS. Histological features only observed in DICER1-mut ERMS were cartilaginous nodules (6/9 DICER1-mut ERMS), in one case accompanied by foci of ossification. Recurrent mutations identified in both DICER1-mut and DICER1-wt ERMS affected KRAS, NRAS, and TP53. Copy number analysis revealed similar structural variations with frequent gains on chromosomes 2, 3, and 8, independent of DICER1 mutation status. Unsupervised hierarchical clustering of array-based whole-genome DNA methylation data of our study cohort together with an extended methylation data set including different RMS subtypes from genitourinary and extra-genitourinary locations (n = 102), revealed a distinct cluster for DICER1-mut ERMS. Such tumors clearly segregated from the clusters of DICER1-wt ERMS, alveolar RMS, and MYOD1-mutant spindle cell and sclerosing RMS. Only one tumor, previously diagnosed as ERMS arising in the maxilla of a 6-year-old boy clustered with DICER1-mut ERMS of the uterus. Subsequent sequencing analysis identified two DICER1 mutations in the latter case. Our results suggest that DICER1-mut ERMS might qualify as a distinct subtype in future classifications of RMS.

Childhood Rhabdomyosarcoma of the Female Genital Tract: Association with Pathogenic DICER1 Variation, Clinicopathological Features, and Outcomes

STUDY OBJECTIVE

Rhabdomyosarcomas (RMSs) of the female genital tract (FGT) have been recently shown to be associated with germline pathogenic variation in DICER1, which can underlie a tumor predisposition disorder. We sought to determine the incidence of a pathogenic variation in DICER1 in a cohort of RMSs of the FGT, as well as to evaluate the clinicopathological features and outcomes of the patients. DESIGN, SETTING, PARTICIPANTS, INTERVENTIONS, AND MAIN OUTCOME MEASURES: We retrospectively reviewed medical records of the patients diagnosed with RMS of the FGT between 1990 and 2019. Molecular genetic sequencing of the tumor to detect an RNase IIIb domain hot spot mutation in DICER1 samples was performed in 7 patients. Individuals with a missense mutation in the tumor were also screened for a loss of function germline mutation in DICER1.

RESULTS

Of 210 cases of pediatric RMS, 11 arose from the FGT. Molecular genetic sequencing of the tumor samples revealed a somatic missense mutation in the RNase IIIb domain of DICER1 in a total of 3 patients, 2 patients with embryonal RMS of the cervix/uterus, and 1 patient with ovarian embryonal RMS. As a result of genetic testing for the loss of function germline mutation in DICER1, a heterozygous pathogenic variant was also found in 2 of these patients.

CONCLUSION

Despite the limited number of patients, our findings suggest that it is important to be aware of the possible association between RMS of FGT and pathogenic germline DICER1 variants because the detection of this mutation in a patient or relatives can provide the opportunity for surveillance of related conditions that might improve long-term outcomes and survival.

DICER1-associated malignancies mimicking germ cell neoplasms: Report of two cases and review of the literature

DICER1 syndrome is characterized by a unique combination of features and a growing list of associated rare tumors. Traditionally, gonadal or extra-gonadal teratomas have not been considered part of this spectrum, with only rare DICER1-related teratoid neoplasms recently reported. Besides, their methylation profiles remain elusive. We report two DICER1-associated malignancies involving the lumbar spine of a 22-year-old man (case 1) and the pelvic cavity of a 14-year-old girl (case 2). Both tumors exhibited teratoma-like features with a high-grade malignant somatic component, including rhabdomyosarcomatous elements for case 1 and a malignant neuroectodermal neoplasm with features of an embryonal tumor with multilayered rosettes (ETMR) for case 2. Both tumors showed strong SALL4 expression and H3K27me3 loss by immunohistochemistry. Next-generation sequencing studies confirmed biallelic DICER1 mutations with additional pathogenic missense mutations in KRAS (case 1) and CTNNB1 (case 2). The methylation profile of case 1 clustered with DICER1-associated sarcomas, whereas case 2 classified as an ETMR (albeit low raw and calibrated score). In conclusion, we report two DICER1-related malignancies with teratoma-like features, further expanding their morphologic spectrum and highlighting the multipotentiality of their presumed cell of origin. Notably, we describe the first ETMR identified outside the CNS with a documented DICER1 biallelic inactivation. Our findings also highlight the potential role of other molecular alterations such as KRAS and CTNNB1 mutations in defining the phenotype of embryonal and primitive DICER1-associated neoplasms, a notion that deserves further studies.

Next-Generation Sequencing Enhances the Diagnosis Efficiency in Thyroid Nodules

BACKGROUND

Though fine-needle aspiration (FNA) improved the diagnostic methods of thyroid nodules, there are still parts of nodules that cannot be determined according to cytology. In the Bethesda system for reporting thyroid cytopathology, there are two uncertain cytology results. Thanks to the development of next-generation sequencing technology, it is possible to gain the genetic background of pathological tissue efficiently. Therefore, a combination of the cytology and genetic background may enhance the accuracy of diagnosis in thyroid nodules.

METHODS

DNA from 73 FNA samples of thyroid nodules belonging to different cytology types was extracted and exome sequencing was performed by the ThyroLead panel. Test for BRAF mutation was also performed by ARMS-qPCR. Information including age, sex, preoperative cytology, BRAF mutation status tested by ARMS-qPCR, and surgical pathology was collected in electronic medical record system.

RESULTS

A total of 71 single nucleotide variants, three fusion gene, and two microsatellite instability-high status were detected in 73 FNA samples. BRAF V600E mutation is the most common mutation in these malignant thyroid nodules. After combining the cytology and genetic background detected by next-generation sequencing, the diagnosis sensitivity was increased from 0.582 (95% CI: 0.441-0.711) to 0.855 (95% CI: 0.728-0.930) (P < 0.001) in our group, while the specificity, 1,000 (95% CI: 0.732-1.000) compared to 0.857 (95% CI: 0.562-0.975) (P = 0.25), did not get affected.

CONCLUSIONS

Next-generation sequencing in thyroid nodules can enhance the preoperative diagnosis sensitivity by fine-needle aspiration alone. It can also provide genetic background for direction of medication. It is possible for clinicians to combine cytology with genetic alterations for a more precise diagnosis strategy of thyroid nodules.

Surveillance recommendations for DICER1 pathogenic variant carriers: a report from the SIOPE Host Genome Working Group and CanGene-CanVar Clinical Guideline Working Group

DICER1 syndrome is a rare genetic disorder that predisposes to a wide spectrum of tumors. Developing surveillance protocols for this syndrome is challenging because uncertainty exists about the clinical efficacy of surveillance, and appraisal of potential benefits and harms vary. In addition, there is increasing evidence that germline DICER1 pathogenic variants are associated with lower penetrance for cancer than previously assumed. To address these issues and to harmonize DICER1 syndrome surveillance programs within Europe, the Host Genome Working Group of the European branch of the International Society of Pediatric Oncology (SIOPE HGWG) and Clinical Guideline Working Group of the CanGene-CanVar project in the United Kingdom reviewed current surveillance strategies and evaluated additional relevant literature. Consensus was achieved for a new surveillance protocol and information leaflet that informs patients about potential symptoms of DICER1-associated tumors. The surveillance protocol comprises a minimum program and an extended version for consideration. The key recommendations of the minimum program are: annual clinical examination from birth to age 20 years, six-monthly chest X-ray and renal ultrasound from birth to age 6 years, and thyroid ultrasound every 3 years from age 8 to age 40 years. The surveillance program for consideration comprises additional surveillance procedures, and recommendations for DICER1 pathogenic variant carriers outside the ages of the surveillance interval. Patients have to be supported in choosing the surveillance program that best meets their needs. Prospective evaluation of the efficacy and patient perspectives of proposed surveillance recommendations is required to expand the evidence base for DICER1 surveillance protocols.

The Role of MicroRNAs in Lung Cancer: Implications for Diagnosis and Therapy

Lung cancer is the first cause of cancer death in the world due to its high prevalence, aggressiveness, late diagnosis, lack of effective treatment and poor prognosis. It also shows high rate of recurrence, metastasis and drug resistance. All these problems highlight the urgent needs for developing new strategies using noninvasive biomarkers for early detection, metastasis and recurrence of disease. MicroRNAs (miRNAs) are a class of small noncoding RNAs that regulate gene expression post-transcriptionally. These molecules found to be abnormally expressed in increasing number of human disease conditions including cancer. miRNAs could be detected in body fluids such as blood, serum, urine and sputum, which leads us towards the idea of using them as non-invasive biomarker for cancer detection and monitoring cancer treatment and recurrence. miRNAs are found to be deregulated in lung cancer initiation and progression and could regulate lung cancer cell proliferation and invasion. In this review, we summarized recent progress and discoveries in microRNAs regulatory role in lung cancer initiation and progression. In addition, the role of microRNAs in EGFR signaling pathway regulation is discussed briefly.

Molecular characterization of DICER1-mutated pituitary blastoma

Pituitary blastoma (PitB) has recently been identified as a rare and potentially lethal pediatric intracranial tumor. All cases that have been studied molecularly possess at least one DICER1 pathogenic variant. Here, we characterized nine pituitary samples, including three fresh frozen PitBs, three normal fetal pituitary glands and three normal postnatal pituitary glands using small-RNA-Seq, RNA-Seq, methylation profiling, whole genome sequencing and Nanostring® miRNA analyses; an extended series of 21 pituitary samples was used for validation purposes. These analyses demonstrated that DICER1 RNase IIIb hotspot mutations in PitBs induced improper processing of miRNA precursors, resulting in aberrant 5p-derived miRNA products and a skewed distribution of miRNAs favoring mature 3p over 5p miRNAs. This led to dysregulation of hundreds of 5p and 3p miRNAs and concomitant dysregulation of numerous mRNA targets. Gene expression analysis revealed PRAME as the most significantly upregulated gene (500-fold increase). PRAME is a member of the Retinoic Acid Receptor (RAR) signaling pathway and in PitBs, the RAR, WNT and NOTCH pathways are dysregulated. Cancer Hallmarks analysis showed that PI3K pathway is activated in the tumors. Whole genome sequencing demonstrated a quiet genome with very few somatic alterations. The comparison of methylation profiles to publicly available data from ~ 3000 other central nervous system tumors revealed that PitBs have a distinct methylation profile compared to all other tumors, including pituitary adenomas. In conclusion, this comprehensive characterization of DICER1-related PitB revealed key molecular underpinnings of PitB and identified pathways that could potentially be exploited in the treatment of this tumor.

Pleuropulmonary blastoma in children and adolescents: The EXPeRT/PARTNER diagnostic and therapeutic recommendations

Pleuropulmonary blastoma (PPB) is a rare cancer occurring mainly during early childhood and often associated with germline DICER1 mutations. It is classified by the macroscopic appearance into three interrelated clinico-pathologic entities on a developmental continuum. Complete tumor resection is a main prognostic factor and can be performed at diagnosis or after neoadjuvant treatment that includes chemotherapy and in some cases radiotherapy. Optimal modalities of neo- or adjuvant treatments can be challenging taking into account potential long-term toxicities in this young population. This paper presents the recommendations for diagnosis and treatment of children and adolescents with PPB elaborated by the European Cooperative Study Group for Pediatric Rare Tumors (EXPeRT) within the European Union-funded project PARTNER (Paediatric Rare Tumours Network - European Registry).

Expression of p53 is significantly associated with recurrence-free survival and overall survival in pleuropulmonary blastoma (PPB): a report from the International Pleuropulmonary Blastoma/DICER1 Registry

Pleuropulmonary blastoma (PPB) is a primary embryonal malignancy of childhood that is characterized by distinct morphologic types: type Ir (regressed), type I (cystic), type II (cystic and solid), and type III (solid). Prognosis varies by PPB type. Most cases are associated with a germline pathogenic mutation in DICER1; however, there is limited data on the factor(s) at a cellular level that drive progression from type I to type III. In this study, we evaluated the expression of p53 and its prognostic implications. A total of 143 PPB cases were included in the study with the following distribution in PPB types: Ir (14%), I (23%), II (32%), and III (31%). P53 expression by immunohistochemistry (IHC) was recorded as four groups: 0%, 1-25%, 26-75%, and 76-100%. All type I PPBs showed 0-25% p53 expression compared to the higher p53 expression (>25%) in type III PPB (p < 0.0001), to support the argument that p53 has a role in tumor progression. In addition, type Ir with the architectural hallmarks of type I PPB, but lacking the primitive cell population, has negligible p53 expression. High p53 expression (staining observed in >25% of the tumor cells) was significantly associated with age over 1 year (p = 0.0033), neoadjuvant therapy (p = 0.0009), positive resection margin (p = 0.0008) and anaplasia (p < 0.0001). P53 expression was significantly associated with recurrence-free survival (p < 0.0001) and overall survival (p = 0.0350), with higher p53 expression associated with worse prognosis. Comparisons of concordance statistics showed no significant difference in prognostication when using morphologic types compared to p53 expression groups (p = 0.647). TP53 sequence was performed in 16 cases; the most common variant identified was a missense variant (12 cases), and in one case a frameshift truncating variant was noted. Based on these findings, we recommend performing p53 IHC in all newly diagnosed cases of types II and III PPB to further aid in risk stratification.

Intrathyroidal Thymus (Incidentaloma) Mimicking Thyroid Neoplasia in DICER1 Syndrome

INTRODUCTION

With the use of ultrasonography for the evaluation of thyroid and nonthyroid neck diseases, the incidental discovery of previously unsuspected thyroid nodules/nonpalpable lesions has increased. Intrathyroidal thymus arises due to aberrant thymic migration during embryogenesis. It is thought to be rare, fulfils the classiccriteria for diagnosis of an incidentaloma and it can be mistaken for a thyroid nodule. Multinodular goiter is the main endocrine manifestation of DICER1 syndrome, a tumor predisposition syndrome. Careful thyroid examination including ultrasound is thus necessary for DICER1 syndrome patients.

CASE REPORT

A 4-year-old prepubertal boy was referred to the pediatric endocrinology department following an earlier diagnosis of pleuropulmonary blastoma (PPB) type III, which is a hallmark component of DICER1 syndrome. The patient underwent surgery followed by chemotherapy. Genetic analysis identified a germline DICER1 pathogenic variant (c.2062C>T, p.R688*)in the child and in 5 relatives. A second somatic DICER1 RNase IIIb hotspot mutation(c.5438A>G, p.E1813G) was identified in DNA extracted from the proband's PPB. He had no goiter on clinical examination, but a heterogenous, well-delineated, avascular, solid and hypoechogenic lesion with pseudomicrocalcifications was observed in the right lobe (4.1 × 3.1 × 2.6 mm), suggestive of thyroid neoplasia. Diagnostic work-up and a 3-year follow-up excluded thyroid neoplasia and confirmed the diagnosis of an intrathyroid benign thymic lesion.

DISCUSSION AND CONCLUSION

This case exemplifies that thyroid incidentalomas in DICER1 syndrome patients should be viewed with great suspicion, but that not all thyroid disorders are indeed DICER1-related in these patients.

Multimodality treatment including whole pleura radiation therapy for DICER1-associated pediatric pleuropulmonary blastoma

Limited data are available regarding radiation therapy in pediatric pleuropulmonary blastoma (PPB). We report the case of a 3-year-old girl with type II PPB successfully treated with trimodality therapy including multiagent chemotherapy, resection, and whole pleura radiation therapy. While longer follow-up is required to confirm ultimate local tumor control and long-term post-treatment sequelae, currently 3.5 years following therapy, she is well, without recurrent disease or observable toxicity. The goal of this report is to add our experience to the literature regarding PPB, its management, and treatment, as prospective randomized controlled trials are not feasible due to the rarity of this disease.

Macrofollicular variant follicular thyroid tumors are DICER1 mutated and exhibit distinct histological features

AIMS

DICER1 germline mutations cause DICER1 syndrome, in which multinodular goitre is a common feature. Recently, somatic DICER1 mutations have been reported in sporadic thyroid carcinomas, of which the newly described macrofollicular variant of follicular thyroid carcinoma (MV-FTC) seems particularly enriched for this aberrancy. We report here histological and genetic findings in five follicular thyroid tumours with macrofollicular architecture (four carcinomas and one adenoma).

METHODS AND RESULTS

We have diagnosed five cases during a year-long period at the Karolinska University Hospital, a tertiary thyroid cancer center with a catchment area of approximately 2.3 million inhabitants. Tumour DNA was interrogated using a commercially available massive parallel sequencing platform. All cases were female patients, ranging from 13 to 33 years at surgery. A single patient was a DICER1 syndrome carrier; the others were sporadic cases. All tumours displayed a macrofollicular architecture with a broad capsule. The MV-FTCs displayed capsular invasion, but never vascular invasion. Areas with degenerative changes (microinfarctions) were noted in all cases, and focal papillary growth was observed in the majority. The Ki-67 proliferation index was always above 4%. All cases displayed DICER1 gene mutations, of which four of five cases displayed RNase IIIb hot-spot missense mutations adjoined by a second, deleterious variant in three of five tumouurs.

CONCLUSIONS

Macrofollicular variants of follicular thyroid tumours are predominantly found in younger females and are strongly linked to somatic DICER1 gene mutations. Histological features such as a broad tumorous capsule, focal infarctions and areas with papillae could constitute clues prompting further genetic analyses.

Genetics of Familial Non-Medullary Thyroid Carcinoma (FNMTC)

Non-medullary thyroid carcinoma (NMTC) is the most frequent endocrine tumor and originates from the follicular epithelial cells of the thyroid. Familial NMTC (FNMTC) has been defined in pedigrees where two or more first-degree relatives of the patient present the disease in absence of other predisposing environmental factors. Compared to sporadic cases, FNMTCs are often multifocal, recurring more frequently and showing an early age at onset with a worse outcome. FNMTC cases show a high degree of genetic heterogeneity, thus impairing the identification of the underlying molecular causes. Over the last two decades, many efforts in identifying the susceptibility genes in large pedigrees were carried out using linkage-based approaches and genome-wide association studies, leading to the identification of susceptibility loci and variants associated with NMTC risk. The introduction of next-generation sequencing technologies has greatly contributed to the elucidation of FNMTC predisposition, leading to the identification of novel candidate variants, shortening the time and cost of gene tests. In this review we report the most significant genes identified for the FNMTC predisposition. Integrating these new molecular findings in the clinical data of patients is fundamental for an early detection and the development of tailored therapies, in order to optimize patient management.

Micro-RNA: The darkhorse of cancer

The discovery of micro RNAs (miRNA) in cancer has opened up new vistas for researchers in recent years. Micro RNAs area set of small, endogenous, highly conserved, non-coding RNAs that control the expression of about 30% genes at post-transcriptional levels. Typically, microRNAs impede the translation and stability of messenger RNAs (mRNA), control genes associated with cellular processes namely inflammation, cell cycle regulation, stress response, differentiation, apoptosis, and migration. Compelling findings revealed that miRNA mutations or disruption correspond to diverse human cancers and suggest that miRNAs can function as tumor suppressors or oncogenes. Here we summarize the literature on these master regulators in clinical settings from last three decades as both abrupt cancer therapeutics and as an approach to sensitize tumors to chemotherapy. This review highlights (I) the prevailing perception of miRNA genomics, biogenesis, as well as function; (II) the significant advancements in regulatory mechanisms in the expression of carcinogenic genes; and (III) explains, how miRNA is utilized as a diagnostic and prognostic biomarker for the disease stage indicating survival as well as therapeutic targets in cancer.

Prevalence and Spectrum of DICER1 Mutations in Adult-onset Thyroid Nodules with Indeterminate Cytology

CONTEXT

DICER1 mutations are found in multinodular goiter and differentiated thyroid carcinoma in children, and can be a manifestation of DICER1 syndrome, but the prevalence of DICER1 mutations and their significance in adult-onset thyroid nodules is unknown.

OBJECTIVE

Determine (1) the prevalence of DICER1 hotspot mutations in thyroid nodules; (2) the frequency of a second DICER1 pathogenic variant in thyroid nodules with DICER1 hotspot mutations; (3) the prevalence of other thyroid cancer driver mutations in thyroid nodules with and without DICER1 hotspot mutations.

METHODS

Population-based study of 14 993 consecutive fine needle aspiration biopsies of thyroid nodules evaluated by ThyroSeq v3. From 214 DICER1 hotspot-positive cases, we selected 61, matched to DICER1 hotspot-negative nodules. We performed full sequencing of all exons and exon-intron boundaries of DICER1.

SETTING

Commercial and university-based laboratories in the United States and Canada.

RESULTS

Among 14 993 thyroid nodules, 214 (1.4%) revealed a DICER1 hotspot mutation. A second pathogenic/likely pathogenic variant in DICER1 was found in 45/59 (76%) DICER1 hotspot-positive nodules studied while no other DICER1 variant was identified in the DICER1 hotspot-negative group by full DICER1 sequencing. Other alterations in thyroid-related genes were significantly more frequent in DICER1 hotspot-negative nodules (32/61) than in DICER1 hotspot--positive nodules (4/59) (P < .0001).

CONCLUSION

DICER1 alterations occur in a proportion of adult thyroid nodules and appear mutually exclusive with alterations in other thyroid cancer-related genes. DICER1 hotspot mutations occur with a second hit in most cases and could suggest occult DICER1 syndrome in adults with thyroid nodules.

Pathological Features of Tumors of the Nervous System in Hereditary Cancer Predisposition Syndromes: A Review

Hereditary cancer predisposition syndromes (HCS) become more recognizable as the knowledge about them expands, and genetic testing becomes more affordable. In this review, we discussed the known HCS that predispose to central and peripheral nervous system tumors. Different genetic phenomena were highlighted, and the important cellular biological alterations were summarized. Genetic mosaicism and germline mutations are features of HCS, and recently, they were described in normal population and as modifiers for the genetic landscape of sporadic tumors. Description of the tumors arising in these conditions was augmented by representative cases explaining the main pathological findings. Clinical spectrum of the syndromes and diagnostic criteria were tabled to outline their role in defining these disorders. Interestingly, precision medicine has found its way to help these groups of patients by offering targeted preventive measures. Understanding the signaling pathway alteration of mammalian target of rapamycin (mTOR) in tuberous sclerosis helped introducing mTOR inhibitors as a prophylactic treatment in these patients. More research to define the germline genetic alterations and resulting cellular signaling perturbations is needed for effective risk-reducing interventions beyond prophylactic surgeries.

Inherited Follicular Epithelial-Derived Thyroid Carcinomas: From Molecular Biology to Histological Correlates

Cancer derived from thyroid follicular epithelial cells is common; it represents the most common endocrine malignancy. The molecular features of sporadic tumors have been clarified in the past decade. However the incidence of familial disease has not been emphasized and is often overlooked in routine practice. A careful clinical documentation of family history or familial syndromes that can be associated with thyroid disease can help identify germline susceptibility-driven thyroid neoplasia. In this review, we summarize a large body of information about both syndromic and non-syndromic familial thyroid carcinomas. A significant number of patients with inherited non-medullary thyroid carcinomas manifest disease that appears to be sporadic disease even in some syndromic cases. The cytomorphology of the tumor(s), molecular immunohistochemistry, the findings in the non-tumorous thyroid parenchyma and other associated lesions may provide insight into the underlying syndromic disorder. However, the increasing evidence of familial predisposition to non-syndromic thyroid cancers is raising questions about the importance of genetics and epigenetics. What appears to be "sporadic" is becoming less often truly so and more often an opportunity to identify and understand novel genetic variants that underlie tumorigenesis. Pathologists must be aware of the unusual morphologic features that should prompt germline screening. Therefore, recognition of harbingers of specific germline susceptibility syndromes can assist in providing information to facilitate early detection to prevent aggressive disease.

Rare DICER1 and Absent FOXL2 Mutations Characterize Ovarian Juvenile Granulosa Cell Tumors

FOXL2 somatic mutation occurs in a high percentage of ovarian adult granulosa cell tumors and DICER1 mutations in a high proportion of Sertoli-Leydig cell tumors. These mutations have only been studied in a limited number of juvenile granulosa cell tumors (JGCTs), and their occurrence and frequency in these neoplasms is controversial. We aimed to determine the frequency of FOXL2 and DICER1 mutations in a large cohort of 50 JGCTs, and to evaluate the prognostic impact of these mutations. A FOXL2 hotspot mutation was found in 2/50 JGCTs. Review of these 2 cases reclassified them as adult granulosa cell tumors. Thus, FOXL2 mutation was absent from our large cohort of JGCTs. DICER1 mutations in the RNase IIIb domain were found in 4 cases. After review of the mutated cases, 1 was reclassified as a gynandroblastoma with a prominent JGCT component. Thus, DICER1 mutations were detected in 3/47 (6%) of pathologically confirmed JGCTs. Our results show that FOXL2 mutations are not present in JGCT, whereas a small percentage of these neoplasms exhibit DICER1 mutations.

Pleuropulmonary Blastoma with Hotspot Mutations in RNase IIIb Domain of DICER 1: Clinicopathologic Study of 10 Cases in a Single-Institute Experience

INTRODUCTION

Pleuropulmonary blastoma (PPB) is a rare sarcomatous malignancy involving the lung and pleura which occurs in early childhood. Cystic PPB in the early stage can be misdiagnosed as other cystic diseases. Early detection of this entity is important for appropriate treatment and prevention of disease progression. Hotspot mutations in the ribonuclease IIIb (RNase IIIb) domain of DICER1 have been reported to have a crucial role as genetic factors of PPB and DICER1 familial syndrome. We reviewed the clinicopathologic findings of PPB and the status of DICER1 hotspot mutation and patients' clinical course.

METHODS

We retrospectively reviewed all patients with histologically confirmed PPB at Asan Medical Center between 2000 and 2017. Ten cases were identified in the database, and their clinicopathologic parameters were evaluated. PPB was classified into the following 3 pathologic subtypes: type I (purely cystic), type II (mixed cystic and solid), and type III (entirely solid). The status of DICER1 mutation in 2 hotspot regions of the RNase IIIb domain was evaluated by Sanger sequencing.

RESULTS

The most frequent PPB type was II (6 cases), followed by I and III (2 cases each). The age at diagnosis ranged from 16 months to 15 years. All patients underwent surgery, and all patients received adjuvant or neoadjuvant chemotherapy. Four of 7 patients had missense mutations in the RNase IIIb hotspot; the base and predicted corresponding amino acid changes were c.5113 G>A (p.E1705K), c.5407 G>A (p.E1803K), c.5425 G>A (p.G1809R), and c.5428 G>T (p.D1810Y). There was no particular association between the presence of the hotspot mutation and histologic type. Nine patients survived with no evidence of disease for a median interval of 93 (range, 13-199) months. Only 1 patient diagnosed with type III PPB at the age of 18 years had recurrence after 20.8 months and eventually died 66 months after the initial diagnosis.

CONCLUSIONS

Late detection of solid PPB is associated with poor prognosis. Considering the rarity of PPB disease and the importance of DICER1 hotspot mutation in pathogenesis, DICER1 hotspot mutation testing and identification in the early cystic stage can improve patient outcomes.

A Cystic Renal Mass in the Setting of a Pneumothorax: More Than Meets the Eye?

DICER1 syndrome is a rare hereditary cancer predisposition syndrome that has relevance to pediatric urology providers due to its association with many various pediatric genitourinary malignancies. We describe the case of a pediatric patient who was eventually diagnosed with a pathogenic DICER1 germline variant after undergoing resection of a cystic nephroma and pleuropulmonary blastoma.

A Genome-First Approach to Characterize DICER1 Pathogenic Variant Prevalence, Penetrance, and Phenotype

IMPORTANCE

Genetic disorders are historically defined through phenotype-first approaches. However, risk estimates derived from phenotype-linked ascertainment may overestimate severity and penetrance. Pathogenic variants in DICER1 are associated with increased risks of rare and common neoplasms and thyroid disease in adults and children. This study explored how effectively a genome-first approach could characterize the clinical traits associated with germline DICER1 putative loss-of-function (pLOF) variants in an unselected clinical cohort.

OBJECTIVE

To examine the prevalence, penetrance, and phenotypic characteristics of carriers of germline DICER1 pLOF variants via genome-first ascertainment.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study classifies DICER1 variants in germline exome sequence data from 92 296 participants of the Geisinger MyCode Community Health Initiative. Data for each MyCode participant were used from the start of the Geisinger electronic health record to February 1, 2018.

MAIN OUTCOMES AND MEASURES

Prevalence of germline DICER1 variation; penetrance of malignant tumors and thyroid disease in carriers of germline DICER1 variation; structured, manual review of electronic health records; and DICER1 sequencing of available tumors from an associated cancer registry.

RESULTS

A total of 92 296 adults (mean [SD] age, 59 [18] years; 98% white; 60% female) participated in the study. Germline DICER1 pLOF variants were observed in 1 in 3700 to 1 in 4600 participants, more than double the expected prevalence. Malignant tumors (primarily thyroid carcinoma) were observed in 4 of 25 participants (16%) with DICER1 pLOF variants, which is comparable (by 50 years of age) to the frequency of neoplasms in the largest registry- and clinic-based (phenotype-first) DICER1 studies published to date. DICER1 pLOF variants were significantly associated with risks of thyroidectomy (odds ratio [OR], 6.0; 95% CI, 2.2-16.3; P = .007) and thyroid cancer (OR, 9.2; 95% CI, 2.1-34.7; P = .02) compared with controls, but there was not a significant increase in the risk of goiter (OR, 1.8; 95% CI, 0.7-4.9). A female patient in her 80s who was a carrier of a germline DICER1 hotspot variant was apparently healthy on electronic health record review. The term DICER1 did not appear in any of the medical records of the 25 participants with a pLOF DICER1 variant, even in those affected with a known DICER1-associated tumor or thyroid phenotype.

CONCLUSIONS AND RELEVANCE

This cohort study was able to ascertain individuals with germline DICER1 variants based on a genome-first approach rather than through a previously established DICER1-related phenotype. Use of the genome-first approach may complement more traditional approaches to syndrome delineation and may be an efficient approach for risk estimation.

Analyzing the Role of DICER1 Germline Variations in Papillary Thyroid Carcinoma

INTRODUCTION

DICER1 is a member of RNase III family that has a pivotal role in the biogenesis of microRNAs, being important for normal development. Dysregulation of DICER1 has been described in different human tumours; however, there is insufficient data on the risk of thyroid cancer in the presence of germline DICER1 variants, particularly when focusing on the background of papillary thyroid carcinoma (PTC). For this purpose, we ascertained the presence of DICER1 variants in 502 (PTC) cases available from The Cancer Genome Atlas (TCGA) research network in a well-characterized pathological context.

MATERIAL AND METHODS

in this study we analyzed 502 samples from 502 patients, described as PTC in the TCGA database. Tumour diagnoses were re-evaluated by 2 pathologists (S.C. and M.S.-S.) on slides available from the database, and clinicopathological and demographic data was examined. Data concerning germline and sporadic DICER1 gene variants as well as frequent mutations in the genes involved in thyroid carcinogenesis (e.g., RAS and BRAFV600E) was retrieved from the database.

RESULTS AND DISCUSSION

We report 1 new germline possibly pathogenic variant, besides 15 others already been identified in ClinVar. We found that the DICER1-positive PTC group more frequently includes PTC variants, namely the oncocytic, follicular, and aggressive (hobnail variant of PTC) variants. A previous association of DICER1 had been demonstrated, mainly with the follicular variant of PTC and follicular thyroid carcinomas. Tumours harbouring germline DICER1 mutations were more frequently "bilateral" and "encapsulated." The frequent association of DICER1 germline variants with other mutations associated with thyroid cancer can reflect an haploinsufficiency tumour suppressor gene function of DICER1, as suggested from the study of animal models.

Predisposition to cancer in children and adolescents

Childhood malignancies are rarely related to known environmental exposures, and it has become increasingly evident that inherited genetic factors play a substantial causal role. Large-scale sequencing studies have shown that approximately 10% of children with cancer have an underlying cancer predisposition syndrome. The number of recognised cancer predisposition syndromes and cancer predisposition genes are constantly growing. Imaging and laboratory technologies are improving, and knowledge of the range of tumours and risk of malignancy associated with cancer predisposition syndromes is increasing over time. Consequently, surveillance measures need to be constantly adjusted to address these new findings. Management recommendations for individuals with pathogenic germline variants in cancer predisposition genes need to be established through international collaborative studies, addressing issues such as genetic counselling, cancer prevention, cancer surveillance, cancer therapy, psychological support, and social-ethical issues. This Review represents the work by a group of experts from the European Society for Paediatric Oncology (SIOPE) and aims to summarise the current knowledge and define future research needs in this evolving field.

Hereditary ovarian tumour syndromes: current update on genetics and imaging

Hereditary ovarian tumour syndromes are a diverse group of hereditary syndromes characterised by the development of specific histotypes of ovarian neoplasms. While BRCA syndromes are exclusively associated with high-grade serous carcinomas, patients with Lynch syndrome show a preponderance of endometrioid subtype of ovarian and endometrial carcinomas. Distinct non-epithelial phenotypes, such as sex cord stromal tumours with annular tubules, Sertoli-Leydig cell tumours, and small cell carcinoma of the hypercalcaemic type occur in patients with Peutz-Jeghers, DICER1, and rhabdoid tumour predisposition syndromes, respectively. Gorlin-Goltz syndrome is characterised by the development of bilateral, multiple ovarian fibromas in 14-24% of patients. Ovarian steroid cell tumours and broad ligament papillary cystadenomas are characteristically found in women with von Hippel-Lindau syndrome. Recent studies have allowed the characterisation of tumour genetics and associated oncological pathways that contribute to tumourigenesis. Implications of the diagnosis of these syndromes on screening, management, and prognosis are discussed.

Hematologic indices in individuals with pathogenic germline DICER1 variants

Pathogenic germline variants in DICER1 underlie an autosomal dominant, pleiotropic tumor-predisposition disorder. Murine models with the loss of DICER1 in hematopoietic stem cell progenitors demonstrate hematologic aberrations that include reductions in red and white blood cell counts, hemoglobin volume, and impaired maturation resulting in dysplasia. We investigated whether hematologic abnormalities such as those observed in DICER1-deficient mice were observed in humans with a pathogenic germline variant in DICER1. A natural history study of individuals with germline pathogenic DICER1 variants and family controls conducted through the National Cancer Institute (NCI) evaluated enrollees at the National Institutes of Health Clinical Center during a comprehensive clinical outpatient visit that included collecting routine clinical laboratory studies. These were compared against normative laboratory values and compared between the DICER1 carriers and controls. There were no statistical differences in routine clinical hematology laboratory studies observed in DICER1 carriers and family controls. A review of the medical history of DICER1 carriers showed that none of the individuals in the NCI cohort developed myelodysplastic syndrome or leukemia. Query of the International Pleuropulmonary Blastoma/DICER1 Registry revealed 1 DICER1 carrier who developed a secondary leukemia after treatment of pleuropulmonary blastoma. We found limited evidence that the hematologic abnormalities observed in murine DICER1 models developed in our cohort of DICER1 carriers. In addition, no cases of myelodysplastic syndrome were observed in either the NCI cohort or the International Pleuropulmonary Blastoma/DICER1 Registry; 1 case of presumed secondary leukemia was reported. Abnormalities in hematologic indices should not be solely attributed to DICER1. This trial was registered at www.clinicaltrials.gov as #NCT01247597.

Programmed Death Ligand 1 Expression and Related Markers in Pleuropulmonary Blastoma

INTRODUCTION

Pleuropulmonary blastoma (PPB), a rare childhood neoplasm of the lung, is linked to pathogenic DICER1 variants. We investigated checkpoint inhibitor markers including Programmed Death Ligand 1 (PD-L1), PD1, CD8 and tumor mutational burden (TMB) in PPB.

MATERIAL AND METHODS

Cases were collected from departmental archives and the International PPB/DICER1 Registry. Immunohistochemistry (IHC) for PD-L1, PD-1, CD8 and DNA mismatch repair (MMR) genes were performed. In addition, normal-tumor paired whole exome sequencing (WES) was performed in two cases.

RESULTS

Twenty-five PPB cases were studied, consisting of Type I (n = 8, including 2 Ir), Type II (n = 8) and Type III (n = 9). PD-L1 combined positive score (CPS) of 1, 4 and 80 was seen in three (3/25, 12.0%) cases of Type II PPB with negative staining in the remaining cases. PD-1 and CD8 stains demonstrated positive correlation (P < .05). The density of PD1 and CD8 in the interface area was higher than within tumor (P < .05). The MMR proteins were retained. TMB was 0.65 mutations/Mb in type II PPB with high expression of PD-L1, and 0.94 mutations/Mb in one negative PD-L1 case with metastatic tumor.

CONCLUSION

A small subpopulation of PPB patient might benefit from checkpoint immunotherapy due to positive PD-L1 staining.