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

The Histological Spectrum of DICER1-Associated Neoplasms

DICER1 syndrome is a heterogeneous cancer predisposition syndrome, characterized by a large variety of benign and malignant tumor types, and caused by germline heterozygous pathogenic variants in the DICER1 gene, which is essential in miRNA processing and RNA interference. The clinical manifestations are diverse, with pleuropulmonary blastoma, Sertoli-Leydig cell tumor, cystic nephroma, uterine cervical embryonal rhabdomyosarcoma, and thyroid follicular nodular disease being the most prevalent tumor types. Since these neoplasms are rare and particularly occur in the pediatric population, pathologists should be aware of the potential relationship of these tumors with an underlying DICER1 syndrome in order to perform or suggest additional molecular pathologic analysis and refer patients and their parents for genetic counseling and testing. This review describes the various DICER1-related tumor types with emphasis on the histological features, reflects on the molecular pathogenesis of DICER1, and aims to raise awareness of this syndrome to facilitate earlier diagnosis.

Data set for reporting paediatric renal tumours: recommendations from the international collaboration on cancer reporting (ICCR)

Tumours arising within the developing kidney of children vary widely in their histological appearance and outcome; optimal therapy requires accurate classification and staging. The two major paediatric cooperative groups provide different therapeutic protocols based on different staging and classification, initially developed to serve patients in North America and Europe, but also used in many other parts/regions of the world. The International Collaboration on Cancer Reporting (ICCR) has developed a structure whereby such complex information may be harmonised, and able to be applied to patients globally. An international expert panel consisting of paediatric pathologists and oncologists produced a set of items critical to cancer reporting and subjected these to review and discussion using the structured processes provided by the ICCR. A formal ICCR structure was assembled, and consensus surrounding elements and their application to different therapeutic protocols was developed. The data set underwent open international consultation. This resulted in the first international data set for Wilms tumour (WT) and other paediatric renal tumours, provided herein. The use of ICCR methods enables a full understanding of highly complex and often overlapping reporting elements by international experts, and the potential of developing a set of commonly applied data elements that are fully defined. This sets the groundwork for future consolidation of definitions and harmonisation of therapies for WT and other paediatric renal tumour patients. It also allows institutions outside the major paediatric cooperative groups to provide therapy based on known elements.

Germline Pathogenic DROSHA Variants Are Linked to Pineoblastoma and Wilms Tumor Predisposition

PURPOSE

DROSHA, DGCR8, and DICER1 regulate miRNA biogenesis and are commonly mutated in cancer. Although DGCR8 and DICER1 germline pathogenic variants (GPV) cause autosomal dominant tumor predisposition, no association between DROSHA GPVs and clinical phenotypes has been reported.

EXPERIMENTAL DESIGN

After obtaining informed consent, sequencing was performed on germline and tumor samples from all patients. The occurrence of germline DROSHA GPVs was investigated in large pediatric and adult cancer datasets. The population prevalence of DROSHA GPVs was investigated in the UK Biobank and Geisinger DiscovEHR cohorts.

RESULTS

We describe nine children from eight families with heterozygous DROSHA GPVs and a diagnosis of pineoblastoma (n = 8) or Wilms tumor (n = 1). A somatic second hit in DROSHA was detected in all eight tumors analyzed. All pineoblastoma tumors analyzed were classified as miRNA processing-altered 1 subtype. We estimate the population prevalence of germline DROSHA loss-of-function variants to be 1:3,875 to 1:4,843 but find no evidence for increased adult cancer risk.

CONCLUSIONS

This is the first report of DROSHA-related tumor predisposition. As pineoblastoma and Wilms tumor are also associated with DICER1 GPVs, our results suggest that the tissues of origin for these tumors are uniquely tolerant of general miRNA loss. The miRNA processing-altered 1 pineoblastoma subtype is associated with older age of diagnosis and better outcomes than other subtypes, suggesting DROSHA GPV status may have important clinical and prognostic significance. We suggest that genetic testing for DROSHA GPVs be considered for patients with pineoblastoma, Wilms tumor, or other DICER1-/DGCR8-related conditions and propose surveillance recommendations through research studies for individuals with DROSHA GPVs.

DICER1 associated cervical embryonal rhabdomyosarcoma in a 59-year-old woman

•We report a case of DICER1-associated ERMS in a 59-year-old woman.•Detection of pathogenic variants in DICER1 supports a diagnosis of ERMS.•Awareness of adult onset ERMS and molecular testing for DICER1 variants can lead to correct diagnosis.

Prognostic Significance of Germline DICER1 Pathogenic or Likely Pathogenic Variants in Outcomes of Ovarian Sertoli-Leydig Cell Tumor

PURPOSE

Sertoli-Leydig cell tumors (SLCTs) are rare sex cord-stromal tumors, representing <0.5% of all ovarian tumors. We analyze the role of germline DICER1 status in outcomes of ovarian SLCT.

METHODS

Patients with SLCT were enrolled in the International Pleuropulmonary Blastoma/DICER1 Registry and/or the International Ovarian and Testicular Stromal Tumor Registry. Medical records were systematically abstracted, and those with known germline DICER1 status were selected for analysis.

RESULTS

Of 162 patients with SLCT, 60% had a germline DICER1 pathogenic or likely pathogenic (P/LP) variant. The adjusted 3-year recurrence-free survival (RFS) was 87.2% (95% CI, 79.4 to 95.8) for patients with a germline DICER1 P/LP variant compared with 78.1% (95% CI, 66.4 to 91.9) for those without a germline DICER1 P/LP variant (P = .043). The adjusted 3-year and 5-year overall survival (OS) was 93.9% (95% CI, 87.3 to 100.0) for those with a germline DICER1 P/LP variant compared with the 3-year OS of 91.3% (95% CI, 83.4 to 100.0) and the 5-year OS of 78.2% (95% CI, 63.8 to 95.9) for those without a germline DICER1 P/LP variant (P = .021). Among patients with a germline DICER1 P/LP variant, the risk of a subsequent, nonrecurrent event was 36.2% (95% CI, 21.4 to 48.1) within 10 years. Previous/concurrent and subsequent neoplasms were rare among those without a germline DICER1 P/LP variant.

CONCLUSION

This cohort study of patients with SLCT demonstrated that those with germline DICER1 P/LP variants had superior RFS and OS even when adjusting for other prognostic factors. Beyond prognostic implications of a germline DICER1 P/LP variant, germline testing helps identify patients at risk of subsequent neoplasms, including metachronous SLCT.

Assessing Sarcoma Awareness Among the General Population in Minnesota: A Cross-Sectional Survey Study from the Minnesota State Fair in 2015 and 2022

Sarcomas are commonly misdiagnosed, and treatment delays negatively impact patient outcomes. The purpose of this study is to explore patient threshold for and timeline to medical evaluation, to identify providers most likely to be contacted first, and to assess general sarcoma knowledge in Minnesota's general population. Voluntary participants were recruited at the 2015 and 2022 Minnesota State Fair to complete a three-part survey. Part 1 assessed evaluation timeline and provider choice, part 2 evaluated sarcoma knowledge via a ten-question survey, and part 3 documented demographics. Responses were electronically recorded, and results were tabulated. Overall, 2124 participants completed some or all of the survey. Part 1: Participants indicated they would seek more urgent treatment for a painful mass compared to a non-painful mass (p < 0.001). The majority (77%) of participants indicated a family medicine physician would be their first contact for painful and non-painful masses. Part 2: There was no difference in overall score (percent correct) when comparing results from 2015 (mean = 40%) to 2022 (mean = 42%) (p = 0.183). Overall, 16% (349/2117) of participants had no correct responses. Individuals who self-identified as Hispanic or Latino ethnicity and a non-White race performed worse (p < 0.001). In general, scores improved with increased education and those with a graduate or professional degree had an estimated 2.515-point increase in score compared to participants with some high school education or high school diploma/general education diploma (p < 0.001). Participants with a healthcare background scored better (p < 0.001). Pain is a driving factor for patient-initiated evaluation, and primary care providers are the most likely first contact for patients. General sarcoma awareness remains low, even among those with advanced degrees and healthcare experience. Ongoing educational efforts are warranted for both the general public and healthcare communities in Minnesota.

Fine Regulation of MicroRNAs in Gene Regulatory Networks and Pathophysiology

MicroRNAs (miRNAs) are ~22-nucleotide small non-coding RNAs that play critical roles in gene regulation. The discovery of miRNAs in Caenorhabditis elegans in 1993 by the research groups of Victor Ambros and Gary Ruvkun opened a new era in RNA research. Typically, miRNAs act as negative regulators of gene expression by binding to complementary sequences within the 3' untranslated regions of their target mRNAs. This interaction results in translational repression and/or target destabilization. The expression levels and activities of miRNAs are fine-tuned by multiple factors, including the miRNA biogenesis pathway, variability in target recognition, super-enhancers, post-transcriptional modifications, and target-directed miRNA degradation. Together, these factors form complex mechanisms that govern gene regulation and underlie several pathological conditions, including Argonaute syndrome, genetic diseases driven by super-enhancer-associated miRNAs, and miRNA-deadenylation-associated bone marrow failure syndromes. In addition, as miRNA genes have evolved rapidly in vertebrates, miRNA regulation in the brain is characterized by several unique features. In this review, we summarize recent insights into the role of miRNAs in human diseases, focusing on miRNA biogenesis; regulatory mechanisms, such as super-enhancers; and the impact of post-transcriptional modifications. By exploring these mechanisms, we highlight the intricate and multifaceted roles of miRNAs in health and disease.

Nodule-Specific NRF2-Targeted Upregulation in Patients With KEAP1 Mutations and Familial Nontoxic Multinodular Goiter

CONTEXT

Kelch-like ECH-associated protein 1 (KEAP1) is associated with nuclear factor erythroid-2-related factor 2 (NRF2) and promotes NRF2 degradation in normal conditions. Genetic abnormality in KEAP1 is a rare disease and presents with familial multinodular goiter.

OBJECTIVE

This study assessed the clinical and molecular findings concerning nodular formation in the thyroid gland of patients harboring KEAP1 germline mutations.

METHODS

Next-generation sequencing analysis targeting goiter-associated genes was performed on 39 patients with familial multinodular goiter. The expression of NRF2-targeted genes from surgical thyroid specimens of patients with KEAP1 mutations were analyzed using a whole-transcript expression array and immunohistochemistry.

RESULTS

We found 5 probands with pathogenic heterozygous mutations in KEAP1 (p.Q86*, p.L136P, p.V411fs, p.R415C, and p.R483H) that had no meaningful concomitance with mutations of other goiter-associated genes at germline and somatic levels. Their common histopathological features showed multinodular goiters in the entire thyroid gland with few degenerative lesions or complications of malignancy and slow proliferation indicating less than 1% at the Ki-67 labeling index. Among 42 NRF2-targeted genes, antioxidant genes were most frequently upregulated (11/12) in the nodule, followed by detoxification genes (6/11). Immunohistochemical analysis showed relatively high expression of glutathione peroxidase 2 and NAD(P)H quinone oxidoreductase 1 (representative NRF2-targeted genes) in the nodules of various patients harboring KEAP1 mutations.

CONCLUSION

KEAP1 germline heterozygous mutations exert excessive NRF2 activity in the thyroid gland and may confer cytoprotective effects even under abundant reactive oxygen species associated with thyroid hormone production, resulting in thyroid hyperplasia with scarce degradation.

Type III pleuropulmonary blastoma: A case report

Pleuropulmonary blastoma (PPB) is an uncommon malignant neoplasm occurring in infants. The disease is intimately linked to mutations in the Dcr-1 homolog and ribonuclease type III (DICER1) genes. Imaging techniques are crucial for diagnosing PPB, yet distinguishing PPB from other pulmonary masses proves challenging. Early detection of PPB is problematic, and it is often diagnosed at an advanced pathological stage with a poor prognosis. The present report discusses a PPB case and evaluates its clinical manifestations, imaging characteristics, pathological features and molecular genetic changes. The patient was a 3-year-old female who presented to Affiliated Hospital of Zunyi Medical University (Zunyi, China) with an unexplained cough. Chest computed tomography revealed a mass in the right thoracic cavity, which was identified as a neoplastic lesion and considered a potential PPB. Surgical intervention was performed. The postoperative pathological examination confirmed PPB (type III) with rhabdomyomatous and chondroid differentiation. After surgery, the patient was treated with regular chemotherapy and at follow-up was doing well without recurrence. In conclusion, PPB represents a rare pathological diagnosis. The present report highlights the significance of noting clinical symptoms in infants, promptly performing pulmonary imaging and pathological examinations, and performing genetic testing when required. Furthermore, long-term surveillance of families with DICER1 syndrome is vital for infants diagnosed with PPB.

Mesenchymal Neoplasms of the Kidney and Perinephric Soft Tissue

Mesenchymal neoplasms of the kidney present challenges because they are uncommon, and because perinephric soft tissue biopsies are sometimes submitted as "kidney" masses, causing diagnostic confusion. Here, the author thoroughly reviews mesenchymal neoplasms of the kidney, including metanephric stromal tumor, classic and cellular congenital mesoblastic nephroma, anaplastic sarcoma and clear cell sarcoma of the kidney, malignant rhabdoid tumor, PEComa/angiomyolipoma, and anastomosing hemangioma. The author also discusses perinephric myxoid pseudotumor of fat, as well as diagnostic pitfalls presented by well-differentiated/dedifferentiated liposarcoma and sarcomatoid carcinoma.

High familial risks in some rare cancers may pinpoint to hidden germline genetics: focus on esophageal, stomach, small intestinal, testis, thyroid and bone cancers

BACKGROUND

Germline genetic susceptibilities of rare cancers of the esophagus, stomach, small intestine, testis, (nonmedullary) thyroid gland and bone with high familial risks are not well known. Here, we use familial risk data from the Swedish Family-Cancer Database which contains records of cancers in Swedish families obtained over a century. We compare familial risks for offspring diagnosed with any of these cancers when their parent had or had not that cancer. We review the global literature of the reported constitutional variants that may explain part of the familial risk.

MAIN BODY

Familial risks for esophageal and stomach cancers are about 2.0 and apart from early-onset stomach cancer few high-risk variants are known. Genetic studies may be hampered by dominant environmental risk factors for these cancers. Small intestinal carcinoids have a very high familial risk (28 between siblings) but no high-risk genes have been identified to explain this. Low-risk polygenic variants have been identified. Small intestinal adenocarcinoma is a manifestation in Lynch syndrome. Testicular and thyroid cancers are characterized by high familial risk (about 5) which may be explained largely by a polygenic background, although thyroid cancer is a component in a number of rare cancer syndromes. Several predisposing genes have been identified for bone cancer (familial risk 7).

CONCLUSIONS

The discussed cancers are rare and they present with a relatively high familial risk, in spite of lacking identified high-penetrant constitutional variants. It is possible that the polygenic component, already recognized for testis cancer, is stronger than previously expected. Thus polygenic models with rare high/moderate- and low-risk variants could fit the familial risk and shape the germline genetic landscape of these cancers. Polygenic background may have clinical implications.

A Novel Pathogenic Variant of DICER1 Gene in a Young Greek Patient with 2 Different Sex-Cord Ovarian Tumors and Multinodular Goiter

DICER1 syndrome (DICERs) represents a tumor predisposition genetic syndrome, inherited in an autosomal dominant manner. Germline loss-of-function variants of the DICER1 gene lead to impaired processing of microRNA, gene expression, and increased risk of tumorigenesis. Although pleuropulmonary blastoma (PPB) is the hallmark of the syndrome, multiple extrapulmonary malignant and non-malignant conditions have also been described, including multinodular goiter (MNG) and sex-cord stromal tumors. MNG is one of the most common components and is associated with an increased risk of thyroid carcinoma. Sertoli-Leydig cell tumor (SLCT) represents the most prevalent type of sex-cord stromal tumor associated with the syndrome, whereas juvenile granulosa cell tumor (JGCT) is considered to be a very rare phenotype. They both may present with abdominal pain due to mass effect and menstrual irregularities in case of hormone production. Although they exhibit low rates of mortality, recurrence rates highly depend on the grade of malignancy. Herein, we report a novel pathogenic DICER1 variant associated with MNG, bilateral ovarian SLCT, and JGCT in a young Greek patient. Clinicians should be aware of a potential germline DICER1 variant when evaluating MNG in young patients, especially if it coexists with other neoplasms.

Recent Advances in Pineoblastoma Research: Molecular Classification, Modelling and Targetable Vulnerabilities

Pineoblastoma (PB) is a rare yet lethal pediatric brain cancer of the pineal gland, a small endocrine organ that secretes melatonin to regulate the circadian rhythm. For PB patients ≤5 years of age, the overall survival rate is approximately 15%; metastatic PB is incurable. Standard treatment, including surgical resection, radiation, and systemic chemotherapy, improves survival but compromises neurocognitive function. A better understanding of the disease and the generation of preclinical models may enable re-evaluation of previous clinical trials, development of precision therapeutic strategies and improve patient outcome. Over the past 5 years, PB has been recognized to include several major subtypes driven by (i) loss of microRNA processing factors DICER and DROSHA characterized by a relatively good prognosis; (ii) loss of the retinoblastoma tumor suppressor RB1; and (iii) amplification or induction of the cMYC protooncogene, with the latter two subtypes exhibiting exceedingly poor prognosis. Recently, mouse models for the major PB subtypes (RB1-, DICER1- and DROSHA-) except MYC- have been established. This progress, including better understanding of the disease, cell of origin, tumor progression, role of autophagy, and targetable vulnerabilities, holds promise for novel therapeutic strategies to combat each subtype of this lethal childhood malignancy.

Investigating Gene Expression Noise Reduction by MicroRNAs and MiRISC Reinforcement by Self-Feedback Regulation of mRNA Degradation

MicroRNA (miRNA) induced silencing complex (miRISC) is the targeting apparatus and arguably rate-limiting step of the miRNA-mediated regulatory subsystem - the major noise reducing though metabolically wasteful mechanism. Recently, we reported that miRISC channels miRNA-mediated regulatory activity back onto their own mRNAs to form negative self-feedback loops, a noise-reduction technique in engineering and synthetic/systems biology. Here, we describe mathematical modeling that predicts mRNA expression noise to correlate negatively with degradation rate (K deg ) and noise reduction by self-feedback control ofK deg . We also calculatedK deg and expression noise of mRNAs detected in a cutting-edge total-RNA single-cell RNA-seq (scRNA-seq) dataset. As predicted, miRNA-targeted mRNAs exhibited higherK deg values in conjunction with lower inter-cell expression noise. Moreover, as predicted by our self-feedback loop model, miRISC mRNAs (AGO1/2/3 and TNRC6A/B/C) exhibited further reduced expression noise. In short, mathematical-modeling and total-RNA scRNA-seq data-analysis shed insight into operational trade-off between noise reduction and metabolic/energetic expenditure in producing miRNA-targeted mRNAs destined for enhanced degradation and translational inhibition, as well as negative self-feedback loop reinforcement of miRISC - the core of miRNA-mediated noise-reduction subsystem. To our knowledge, this is the first report of concurrent mRNA degradation and expression noise analyses and of noise reduction by self-feedback control of mRNA degradation.

Diagnosis and treatment of thyroblastoma: a case report and review of literature

Background and objective

The diagnosis of thyroblastoma initially identified as a thyroid malignant teratoma was subsequently classified as a distinct entity by the World Health Organization (WHO) in 2022. This classification was based on the observation that the tumor presents with independent primitive multilineage elements and is frequently associated with DICER1 hotspot mutations.The objective of this study was to explore and investigate the clinicopathologic characteristics, molecular features and treatment strategies of patients with thyroblastoma, followed by a review of the previous relevant literature.

Methods

The clinical manifestations, pathological characteristics, molecular features and treatment strategies of the initial case of thyroblastoma pathologically confirmed in China were analyzed.

Results

The tumor was revealed to have high invasive potential, rapid disease progression, and primitive multilineage elements of pathology, including immature thyroid epithelium, spindled mesenchymal proliferations, and neuroepithelial blastema. Next-generation sequencing (NGS) confirmed the presence of germline DICER1 heterozygous pathogenic mutation at p.G1784* in patient, accompanied by the somatic hotspot mutation at p.E1813D of the RNase IIIb domain. Despite local thyroid tumor resection, the disease continued to progress rapidly. However, chemotherapy with BEP led to a reduction in the tumor. The patient's progression-free survival (PFS) reached 15 months following the administration of BEP chemotherapy in conjunction with local radiotherapy. The patient ultimately died of cardiac arrest resulting from the progression of the cancer thrombus to the right atrium and right ventricle.

Conclusion

Although thyroblastoma has been treated as a separate entity with its distinctive morphologic and molecular characteristics, its clinicopathological features, diagnosis and treatment methods and prognosis remain poorly understood, which requires more accumulated clinical case data to provide basis for the correct diagnosis and treatment in the future.

Integrated molecular characterization reveals the pathogenesis and therapeutic strategies of pulmonary blastoma

Background

Pulmonary blastoma (PB) is a rare subtype of lung cancer. Currently, the underlying pathogenesis mechanisms of PB have not been fully illustrated, and the therapeutic approach for this entity is limited.

Methods

Whole-exome sequencing (WES), RNA sequencing, and DNA methylation profiling are applied to seven PB patients. Multi-omics data of pulmonary sarcomatoid carcinoma (PSC) and pituitary blastoma (PitB) from previous studies are invoked to illuminate the associations among PB and these malignacies.

Results

We portray the genomic alteration spectrum of PB and find that DICER1 is with the highest alteration rate (86 %). We uncover that DICER1 alterations, Wnt signaling pathway dysregulation and IGF2 imprinting dysregulation are the potential pathogenesis mechanisms of PB. Moreover, we reveal that the integrated molecular features of PB are distinct from PSC, and the molecular characteristics of PB are more similar to PitB than to PSC. Pancancer analysis show that the tumor mutation burden (TMB) and leukocyte fraction (LF) of PB are low, while some cases are positive for PD-L1 or have CD8-positive focal areas, implying the potential applicability of immunotherapy in selected PB patients.

Conclusion

This study depicts the integrated molecular characteristics of PB and offers novel insights into the pathogenesis and therapeutic strategies of PB.

Pleuropulmonary blastoma and DICER1-related tumor predisposition: from clinicopathologic observations to clinical trial

PURPOSE OF REVIEW

Pleuropulmonary blastoma (PPB) is a rare primary lung neoplasm of infancy and childhood. The purpose of this review is to highlight recent developments in our understanding of PPB and research strategies to facilitate future rare cancer research.

RECENT FINDINGS

The International PPB/DICER1 Registry has recently assembled the largest-ever cohorts of type I and Ir PPB and type II and III PPB. These analyses were strengthened by robust histologic, genetic and longitudinal data made possible by systematic data collection and abstraction and dedicated central pathology review. These cohorts have laid the groundwork for a prospective consortium-based clinical trial to assess response to camptothecins in type II and III PPB and standardize the use of chemotherapy in type I PPB.

SUMMARY

Significant strides in the study of PPB have been made through clinical, laboratory and translational research, multidisciplinary collaborations and the generous contributions of patients, families and referring physicians. Ongoing advancements will continue to depend on multidisciplinary, multiperspective global collaborations.

Update on Pediatric Surveillance Recommendations for PTEN Hamartoma Tumor Syndrome, DICER1-Related Tumor Predisposition, and Tuberous Sclerosis Complex

Phosphate and tensin homolog hamartoma tumor syndrome, DICER1-related tumor predisposition, and tuberous sclerosis complex are rare conditions, which each increases risk for distinct spectra of benign and malignant neoplasms throughout childhood and adulthood. Surveillance considerations for each of these conditions focus on patient and family education, early detection, and multidisciplinary care. In this article, we present updated surveillance recommendations and considerations for children and adolescents with phosphate and tensin homolog hamartoma tumor syndrome, DICER1-related tumor predisposition, and tuberous sclerosis complex and provide suggestions for further research in each of these conditions.

Cystic masses of the pediatric lung: update on congenital pulmonary airway malformation and its differential diagnosis

Localized cystic lung lesions in pediatric patients encompass a spectrum of benign and rare malignant conditions that are quite distinct from cystic lung disease arising in adulthood. The majority have historically fallen under the diagnostic category of "congenital pulmonary airway malformation," a term that has been used to denote a diverse group of diseases ranging in etiology from ectopia to bronchial atresia to mosaic oncogenic mutation or neoplasia. This article reviews the clinical characteristics, gross and histologic features, and pathogenetic underpinnings of congenital pulmonary airway malformation as well as lesions that enter its histologic differential diagnosis. In light of ongoing advances in the field, previously proposed pathology-based classification schemes are critically appraised, and a new diagnostic framework is considered.

Rhabdomyosarcoma in children and young adults

Rhabdomyosarcoma (RMS) is the most common soft tissue malignancy in childhood, accounting for 3% of all pediatric malignancies and 50% of all pediatric soft tissue sarcomas. In adolescents and young adults (AYA) however, RMS comprises only 6.5% of all soft tissue sarcomas. Historically, diagnosis and treatment of RMS was based on histologic recognition of the alveolar subtype, which was associated with a worse prognosis. Within the past 20 years, the biologic characteristics of RMS have become clearer, with canonical fusion drivers, PAX3/7::FOXO1, characterizing the alveolar subtype (ARMS) and in turn associated with poor outcome, while chromosomal gains/losses in addition to RAS pathway alterations characterize the embryonal subtype (ERMS). Accordingly, detection of a FOXO1 gene fusion has become a commonplace diagnostic and prognostic tool allowing tumors to be treated based on presence or absence of a FOXO1 gene fusion. However, these cytogenetic and molecular alterations represent only a portion of the molecular landscape found in RMS, and other alterations are found with increasing frequency in various subsets of RMS. Clinical trials basing risk stratification on the presence or absence of the canonical PAX3/7::FOXO1 fusions have had success in identifying the poor responders. Due to poor outcomes, the presence of MYOD1 and TP53 alterations which are common in spindle cell sclerosing RMS (SSRMS) and RMS with anaplasia have also been integrated into trial risk stratification. Therefore, complete histologic and immunophenotypic characterization remain important to better recognize and study these rare subsets of RMS. This article will discuss the challenges of RMS classification including how to combine morphologic, immunophenotypic and molecular data to arrive at an integrated diagnosis. The use of newer techniques such as liquid biopsy and methylation profiling, will also continue to shape the classification of RMS and may further refine risk stratification and prognosis.

Primary intracranial sarcoma associated with DICER1 mutant: a case report and preclinical investigation

Primary intracranial sarcoma (PIS) is a rare and aggressive pediatric brain tumor, which is partially associated with DICER1 mutant. Although the molecular genetic characteristics of this tumor have previously been investigated, novel therapeutic targets remain unclear. Further, the lack of faithful preclinical models has hampered the development of novel therapeutic strategies. Herein, we describe a pediatric case of PIS with DICER1 mutant and describe the development of the first novel patient-derived xenograft (PDX) model of this rare tumor. Somatic genomic profiling of the tumor revealed mutations in DICER1, TP53, and ATRX. Germline analysis further revealed a pathogenic variant of DICER1, significant for the diagnosis and management of hereditary tumor predisposition syndrome. Overall, we demonstrated that the PDX model faithfully retained the phenotype and genotype of the patient's tumor, as well as the DNA methylation profile. Through high-throughput drug screening using PDX tumor cells, we found that activation of the retinoic acid receptor (RAR) signaling pathway reduced tumor cell viability. These findings indicate that the RAR signaling pathway is a potential therapeutic target for PIS in DICER1 mutant.

DICER1-Related Tumor Predisposition: Identification of At-risk Individuals and Recommended Surveillance Strategies

PURPOSE

DICER1-related tumor predisposition increases risk for a spectrum of benign and malignant tumors. In 2018, the International Pleuropulmonary Blastoma (PPB)/DICER1 Registry published guidelines for testing- and imaging-based surveillance of individuals with a known or suspected germline DICER1 pathogenic or likely pathogenic (P/LP) variant. One of the goals of the Registry is to continue to refine these guidelines as additional data become available.

EXPERIMENTAL DESIGN

Individuals were enrolled in the International PPB/DICER1 Registry, the International Ovarian and Testicular Stromal Tumor Registry, and/or the NCI Natural History of DICER1 Syndrome study.

RESULTS

Review of participant records identified 713 participants with a germline DICER1 P/LP variant from 38 countries. To date, 5 cases of type I and 29 cases of type Ir PPB have been diagnosed by surveillance in enrolled individuals. One hundred and three individuals with a germline P/LP variant developed a primary ovarian Sertoli-Leydig cell tumor at a median age of 14 years (range: 11 months-66 years); 13% were diagnosed before 8 years of age, the current age of onset of pelvic surveillance. Additionally, 4% of Sertoli-Leydig cell tumors were diagnosed before 4 years of age.

CONCLUSIONS

Ongoing data collection highlights the role of lung surveillance in the early detection of PPB and suggests that imaging-based detection and early resection may decrease the risk of advanced PPB. DICER1-related ovarian tumors were detected before 8 years of age, prompting the Registry to recommend earlier initiation of ovarian surveillance with pelvic ultrasound beginning at the time of detection of a germline DICER1 P/LP variant.

Shedding light on the DICER1 mutational spectrum of uncertain significance in malignant neoplasms

The Dicer protein is an indispensable player in such fundamental cell pathways as miRNA biogenesis and regulation of protein expression in a cell. Most recently, both germline and somatic mutations in DICER1 have been identified in diverse types of cancers, which suggests Dicer mutations can lead to cancer progression. In addition to well-known hotspot mutations in RNAase III domains, DICER1 is characterized by a wide spectrum of variants in all the functional domains; most are of uncertain significance and unstated clinical effects. Moreover, various new somatic DICER1 mutations continuously appear in cancer genome sequencing. The latest contemporary methods of variant effect prediction utilize machine learning algorithms on bulk data, yielding suboptimal correlation with biological data. Consequently, such analysis should be conducted based on the functional and structural characteristics of each protein, using a well-grounded targeted dataset rather than relying on large amounts of unsupervised data. Domains are the functional and evolutionary units of a protein; the analysis of the whole protein should be based on separate and independent examinations of each domain by their evolutionary reconstruction. Dicer represents a hallmark example of a multidomain protein, and we confirmed the phylogenetic multidomain approach being beneficial for the clinical effect prediction of Dicer variants. Because Dicer was suggested to have a putative role in hematological malignancies, we examined variants of DICER1 occurring outside the well-known hotspots of the RNase III domain in this type of cancer using phylogenetic reconstruction of individual domain history. Examined substitutions might disrupt the Dicer function, which was demonstrated by molecular dynamic simulation, where distinct structural alterations were observed for each mutation. Our approach can be utilized to study other multidomain proteins and to improve clinical effect evaluation.

DICER1 Mutations Define the Landscape of Poorly Differentiated Thyroid Carcinoma in Children and Young Adults : Case Report and Literature Review

Poorly differentiated thyroid carcinoma (PDTC) is a rare malignancy, representing ~1% of all thyroid tumors. It is characterized by high-grade histologic features without the anaplastic characteristics observed in anaplastic thyroid carcinoma. Although rare in children and young adults, there is emerging evidence of clinical and genetic differences with PDTC in adults. We present a case of a 19-year-old female with a right thyroid lobe nodule classified as an EU-TIRADS 5 lesion. Subsequent FNAC showed a cellular aspirate of solitary cells and scant microfollicles with variable nuclear irregularities, which was designated a Bethesda class IV lesion. Thyroidectomy revealed histopathological features consistent with PDTC, including solid/trabecular growth, increased mitotic activity, central necrosis, and extensive vascular invasion. Molecular analysis identified germline and somatic DICER1 mutations in the absence of other established driver mutations of PDTC. This case report describes the fourth reported patient with a PDTC and germline DICER1 mutation. Our findings contribute to a limited body of literature on pediatric/young adult PDTC cases and highlight the pivotal role of DICER1 mutations. Emerging evidence suggests that pediatric PDTC may exhibit unique clinical and genetic characteristics, prompting further research into its molecular profile.

Exomic and epigenomic analysis of pulmonary blastoma

OBJECTIVE

Pulmonary blastoma is a rare, biphasic, adult-onset lung tumor. In this study, we investigate whether DICER1 pathogenic variants are a feature of pulmonary blastomas through in-depth analysis of the molecular events defining them.

METHODS

We performed exome-wide sequencing and DNA methylation profiling of 8 pulmonary blastomas from 6 affected persons.

RESULTS

We identified biallelic somatic DICER1 pathogenic variants in 7 of 8 cases. The remaining case had a solitary missense pathogenic variant in the RNase IIIb domain of DICER1. Six of 8 cases carried a CTNNB1 hotspot variant and 4 of 8 had a somatic pathogenic variant in TP53. Methylation analysis showed that the pulmonary blastomas clustered with other DICER1-mutated tumors and not with other more common types of lung cancer.

CONCLUSION

We conclude somatic DICER1 pathogenic variants are the major driver of pulmonary blastoma and are likely to act in conjunction with CTNNB1 hotspot variants that are often present.

Botryoid-type Embryonal Rhabdomyosarcoma: A Comprehensive Clinicopathologic and Molecular Appraisal With Cross-comparison to its Conventional-type Counterpart

Embryonal rhabdomyosarcoma (ERMS) is the most common subtype of RMS, occurring in soft tissue and visceral sites of young children, and is associated with favorable outcomes. A subset occurs in mucosal-lined luminal structures, displaying a unique grape-like growth termed as "botryoid-type." To further delineate the differences between conventional (cERMS) and botryoid-type (bERMS) RMS, we performed a comparative histologic review and comprehensive molecular profiling of 48 cases (25 bERMS and 23 cERMS). All tumors were subjected to a hybridization capture-based targeted matched tumor-normal DNA NGS assay. The mean age was 17 and 7 years for bERMS and cERMS, respectively. Most bERMS were female with a predilection for the gynecologic tract (75%), while cERMS had a slight male predominance and were preferentially located in abdominopelvic and paratesticular sites (30%, each). All bERMS exhibited an exophytic, bulbous architecture accompanied by a subepithelial "cambium layer." Distinctive germline alterations were detected, with DICER1 (18%) and FH (6%) mutations only in bERMS, and rare TP53, VHL, and APC mutations in cERMS. Similarly, contrasting somatic genomic landscapes were observed, with frequent DICER1 (52%, P**<0.0001) and TP53 (36%, P*<0.05) alterations exclusively in bERMS. Cartilaginous differentiation was only observed in DICER1-mutated bERMS. All patients had longitudinal follow-up. bERMS patients with somatic/germline DICER1 mutations showed significantly improved recurrence-free survival compared with that of DICER1-wild type patients (P*<0.05). Moreover, bERMS showed improved disease-specific survival compared with that of cERMS, with 8% versus 30% (P*<0.05) dead of disease, respectively. In summary, we compare the molecular underpinnings of the largest cohort of bERMS and cERMS with targeted DNA sequencing and long-term follow-up data. Our findings reveal divergent genomic topographies between the 2 groups, with bERMS showing unique germline and somatic abnormalities, including enrichment in DICER1 and TP53 alterations, and a trend towards improved survival.

Sertoli-Leydig tumor and DICER1 gene mutation: A case series and literature review

OBJECTIVE

Sertoli-Leydig cell tumors (SLCTs) are rare neoplasms occurring in young women with 60% associated with DICER1 mutations. This is only the second published case series of patients with SLCTs with associated DICER1 gene alterations. DICER1 syndrome is a rare inherited tumor-susceptibility syndrome affecting organs such as the ovaries. We use this case series to inform readers on this increasingly important condition in gynecology.

METHODS AND RESULTS

We present three young females presenting with secondary amenorrhoea, hirsutism, acne and in one case tonic-clonic seizures. All cases had high testosterone levels and an adnexal mass on ultrasound. Following surgical removal, pathology confirmed SLCTs and genetic testing followed. All three patients had DICER1 syndrome with two patients subsequently found to be related.

DISCUSSION

The prevalence of DICER1 syndrome in the population is estimated to be 1 in 10 000 with a spectrum of sex cord stromal tumors affecting young women. The associated pathological classifications and management. This paper describes the DICER1 gene and the associated tumor predisposition syndrome alongside a surveillance protocol for use in clinical practice. It promotes discussion over the importance of early clinical genetics involvement in sex-cord stromal tumors and the associated difficulties in counseling in a young patient population. Genetic testing and early detection are imperative for targeted surveillance of at-risk organs to be performed but despite this there is no international guidance. The cases highlight the psychological impact of tumors in young patients and provokes an ethical discussion over DICER1 gene's inclusion in preimplantation genetics.

CONCLUSIONS

DICER1 syndrome is a rare but increasingly important condition in pediatric and adolescent gynecology with a paucity of published data and case reports. This makes international consensus on management and surveillance difficult.

Outcomes in ovarian Sertoli-Leydig cell tumor: A report from the International Pleuropulmonary Blastoma/DICER1 and Ovarian and Testicular Stromal Tumor Registries

OBJECTIVE

Sertoli-Leydig cell tumors (SLCTs) are rare sex cord-stromal tumors, representing <0.5% of all ovarian tumors. We sought to describe prognostic factors, treatment and outcomes for individuals with ovarian SLCT.

METHODS

Individuals with SLCT were enrolled in the International Pleuropulmonary Blastoma/DICER1 Registry and/or the International Ovarian and Testicular Stromal Tumor Registry. Medical records were systematically abstracted, and pathology was centrally reviewed when available.

RESULTS

In total, 191 participants with ovarian SLCT enrolled, with most (92%, 175/191) presenting with FIGO stage I disease. Germline DICER1 results were available for 156 patients; of these 58% had a pathogenic or likely pathogenic germline variant. Somatic (tumor) DICER1 testing showed RNase IIIb hotspot variants in 97% (88/91) of intermediately and poorly differentiated tumors. Adjuvant chemotherapy was administered in 40% (77/191) of cases, and among these, nearly all patients received platinum-based regimens (95%, 73/77), and 30% (23/77) received regimens that included an alkylating agent. Three-year recurrence-free survival for patients with stage IA tumors was 93.6% (95% CI: 88.2-99.3%) compared to 67.1% (95% CI: 55.2-81.6%) for all stage IC and 60.6% (95% CI: 40.3-91.0%) for stage II-IV (p < .001) tumors. Among patients with FIGO stage I tumors, those with mesenchymal heterologous elements treated with surgery alone were at higher risk for recurrence (HR: 74.18, 95% CI: 17.99-305.85).

CONCLUSION

Most individuals with SLCT fare well, though specific risk factors such as mesenchymal heterologous elements are associated with poor prognosis. We also highlight the role of DICER1 surveillance in early detection of SLCT, facilitating stage IA resection.

Nasal and sinonasal tumors formed by atypical adenomatous lesions arising in respiratory epithelial adenomatoid hamartoma/seromucinous hamartoma

Two benign adenomatous lesions are commonly recognized within the sinonasal tract, namely respiratory epithelial adenomatoid hamartoma (REAH) and seromucinous hamartoma (SH). We present 10 hitherto unrecognized benign polypoid nasal and sinonasal tumoriform lesions having in average 3.6 cm in largest dimension, which are histogenetically related to SH and REAH. In addition to typical structures of REAH and SH, these lesions contained an additional characteristic and slightly atypical adenomatous component, which we termed atypical sinonasal glands arising in SH (ASGSH). ASGSH often produced deep red colored secretion with peripheral clearing similar to that seen in thyroid follicles. In contrast to SH, ASGSH was endowed by both secretory and myoepithelial layers and had mostly angulated shapes with snout-like protrusions into the lumens. Both layers were formed by an irregular, disorganized, and often incomplete cell lining, which had slightly atypical cytological features without mitoses. In 3 cases, ASGSHs revealed sebaceous differentiation, and in 3 cases the stroma produced a well-differentiated cartilage. Neoplastic nature of ASGSH was supported by finding of various mutations as revealed by next generation sequencing in five cases. In two cases each, we found identical mutations in BRAF gene (Val600Glu), and RET gene (Arg912Trp), respectively and in one case FAT1 gene alteration (Pro1665Leu).

DICER1 Syndrome Discovered Through an Eye Tumor

This case report describes a patient with medulloepithelioma of the ciliary body that was subsequently diagnosed as DICER1 syndrome.

DICER1 Tumor Syndrome: A Retrospective Review and Future Perspectives

DICER1 syndrome, a rare autosomal dominant genetic disorder, stems from mutations in the DICER1 gene, disrupting RNA interference and leading to various tumors. These tumors, affecting organs like the lung, kidney, ovaries, and brain, pose diagnostic challenges due to diverse presentations. Understanding DICER1-associated tumors, including pleuropulmonary blastoma, ovarian Sertoli–Leydig cell tumors, and others, is vital for early detection and management. Surgical resection, chemotherapy, and targeted therapies are primary treatment modalities, with genetic counseling playing a crucial role. Multidisciplinary care is essential for optimal management, offering hope for improved outcomes in affected individuals.

Prevalence of lung cysts in adolescents and adults with a germline DICER1 pathogenic/likely pathogenic variant: a report from the National Institutes of Health and International Pleuropulmonary Blastoma/DICER1 Registry

BACKGROUND

Pleuropulmonary blastoma (PPB), the hallmark tumour associated with DICER1-related tumour predisposition, is characterised by an age-related progression from a cystic lesion (type I) to a high-grade sarcoma with mixed cystic and solid features (type II) or purely solid lesion (type III). Not all cystic PPBs progress; type Ir (regressed), hypothesised to represent regressed or non-progressed type I PPB, is an air-filled, cystic lesion lacking a primitive sarcomatous component. This study aims to evaluate the prevalence of non-progressed lung cysts detected by CT scan in adolescents and adults with germline DICER1 pathogenic/likely pathogenic (P/LP) variants.

METHODS

Individuals were enrolled in the National Cancer Institute Natural History of DICER1 Syndrome study, the International PPB/DICER1 Registry and/or the International Ovarian and Testicular Stromal Tumor Registry. Individuals with a germline DICER1 P/LP variant with first chest CT at 12 years of age or older were selected for this analysis.

RESULTS

In the combined databases, 110 individuals with a germline DICER1 P/LP variant who underwent first chest CT at or after the age of 12 were identified. Cystic lung lesions were identified in 38% (42/110) with a total of 72 cystic lesions detected. No demographic differences were noted between those with lung cysts and those without lung cysts. Five cysts were resected with four centrally reviewed as type Ir PPB.

CONCLUSION

Lung cysts are common in adolescents and adults with germline DICER1 variation. Further study is needed to understand the mechanism of non-progression or regression of lung cysts in childhood to guide judicious intervention.

Recurrent primary intracranial sarcoma, DICER1-mutant in a pediatric patient with DICER1 syndrome: the importance of molecular testing

Pediatric intracranial sarcomas are rare, aggressive tumors with a poor prognosis in general. Here we report the case of a child who was initially diagnosed with a primary intracranial sarcoma, DICER1-mutant; subsequent genetic analyses confirmed a pathogenic germline DICER1 mutation. She received multimodal standard treatments consisting of surgery, radiotherapy and chemotherapy. The tumor recurred 2.5 years later within the surgical cavity. Following the gross tumor resection of this new lesion, the same multimodal standard approach was used. From a molecular perspective, evidence of hyperactivation of the MAPK-kinase pathway with a pathogenic KRAS mutation at both diagnosis and recurrence was present. The patient is currently in remission, 18 months post-end of treatment.

Extraskeletal chondroma of the toe in a child with DICER1 tumor predisposition syndrome: support for a dominant negative mechanism

DICER1 tumor predisposition syndrome is a pleiotropic disorder that gives rise to various mainly pediatric-onset lesions. We report an extraskeletal chondroma (EC) of the great toe occurring in a child who, unusually, carries a germline "hotspot" missense DICER1 variant rather than the more usual loss-of-function (LOF) variant. No heterozygous LOF allele was identified in the EC. We demonstrate this variant impairs 5p cleavage of precursor-miRNA (pre-miRNA) and competes with wild-type (WT) DICER1 protein for pre-miRNA processing. These results suggest a mechanism through which a germline RNase IIIb variant could impair pre-miRNA processing without complete LOF of the WT DICER1 allele.

Presentation and Care for Children with Peripheral Precocious Puberty

Peripheral precocious puberty (PPP) refers to the early onset of sexual maturation that is independent of central nervous system control. The extensive differential diagnosis includes congenital and acquired causes. Presenting features depend on which class of sex steroids is involved, and diagnosis rests on hormonal and, if indicated, imaging and/or genetic studies. Effective treatment exists for nearly all causes of PPP. Ongoing research will advance our therapeutic armamentarium and understanding of the pathophysiologic basis of these conditions.

Familial syndromes associated with testicular and paratesticular neoplasms: a comprehensive review

A syndromic association between a subset of testicular/paratesticular neoplasms is well established. Such examples include Carney complex and large cell calcifying Sertoli cell tumor, Peutz-Jeghers syndrome and intratubular large cell hyalinizing Sertoli cell neoplasia, and VHL syndrome and clear cell papillary cystadenoma of the epididymis.However, recent studies proposed potential novel links between some testicular and paratesticular neoplasms with certain tumor syndromes. While more studies are still needed to solidify these associations, recent research suggests that a subset of Leydig cell tumors may arise in patients with hereditary leiomyomatosis and renal cell carcinoma syndrome or that some seminomas may occur in Lynch syndrome patients. Additionally, an association between testicular sex cord stromal tumors and paratesticular sarcomas with Familial adenomatous polyposis syndrome and DICER1 syndrome, respectively, has been proposed as well. This review provides a comprehensive overview of the intricate relationship between familial syndromes and associated testicular and paratesticular tumors, shedding light on their clinicopathological and molecular characteristics.

Pathogenic Somatic Mutation of DICER1 and Clinicopathological Features in Nasal Chondromesenchymal Hamartomas: A Series of Nine Cases

Nasal chondromesenchymal hamartoma (NCMH) is a rare benign polypoid mesenchymal tumor arising in the nasal cavity and/or paranasal sinuses. Recognizing these sporadic, rare lesions is crucial, as surgical complete removal of the mass is the common treatment approach. This retrospective study analyzed the demographics, symptoms, and imaging data of 9 patients diagnosed with NCMH between January 2017 and June 2023, possibly representing the largest single-center adult case cohort to date. Diagnostic techniques included nasal endoscopy, CT/MRI scan, immunohistological studies, and morphologic comparisons. Pathologic specimens were subjected to Sanger sequencing of exons 24 and 25 of DICER1. The average age of 9 cases was 24.4 years, and the oldest was 55 years. Four of the patients were children, ranging from 1 year old to 11 years old, with an average of 4.5 years. Nasal congestion is the most common registered symptom. Endoscopic findings showed that most patients had smooth pink neoplasms or polypoid masses in the nasal meatus. Radiologic scanning revealed soft-tissue density masses that occupied the nasal cavity. Histologically, the characteristic structure of NCMHs is immature cellular cartilage nodules and mature cartilage nodules distributed in a loose mucoid matrix. Five of the 9 patients had somatic DICER1 missense mutations. Four of the patients with DICER1-mutated NCMH exhibited a p.E1813 missense hotspot mutation. We also report a case of a rare p.P1836H missense mutation. The detected DICER1 somatic mutations provide compelling evidence of an association with the DICER1 tumor family. We emphasize the importance of pathologic consultation and the need for pathologists to accumulate experience in NCMH diagnosis to avoid misdiagnosis.

Ultrasound-Histopathological Presentation of Thyroid and Ovary Lesions in Adolescent Patients with DICER1 Syndrome: Case Reports and Literature Overview

BACKGROUND

DICER1, a cancer predisposition syndrome (CPS), seems to escape timely diagnosis in pediatric patients. Case report 1: A 16-year-old female patient was referred to the endocrinology ward due to a large goiter. Her medical history indicated normal sexual maturation, with menarche occurring at 13.5 years. Over the past 2.5 years, she had developed pronounced androgenic symptoms, including a deepened male voice; facial, back, and neckline acne; hirsutism; and menstrual irregularities leading to secondary amenorrhea. A thyroid ultrasound identified a multinodular goiter (MNG) with cystic-solid lesions containing calcifications. An abdominal ultrasound identified a 5.7 × 6.9 cm solid mass in the right adnexal region, displacing the uterus to the left. Histopathological examination confirmed a Sertoli-Leydig cell tumor. The patient was subjected to a total thyroidectomy. Histopathology revealed benign follicular cell-derived neoplasms. Thyroid follicular nodular disease (TFND) was diagnosed bilaterally. DNA analysis using NGS, confirmed via the Sanger method, revealed a pathogenic heterozygotic variant c.2953C>T [p.Gln985*] in exon 18 of the DICER1 gene. Case report 2: A 12-year-old male patient was admitted to the pediatric surgery unit due to a 33 mL goiter. A month prior to his admission, the patient discovered a palpable nodule in his neck, accompanied by hoarseness. An ultrasound revealed MNG. Molecular analysis revealed a pathogenic heterozygotic variant c.2782C>T [p.Gln928*] in exon 17 of the DICER1 gene. Subsequently, a total thyroidectomy was performed, and histopathological examination revealed TFND bilaterally.

CONCLUSIONS

Recent advances in genetic evaluation and in histological approaches indicate that MNG/TFND, although rare in the pediatric population, when accompanied by characteristic ultrasound and histopathological features, and by additional features such as androgenization, may warrant assessment also of the DICER1 gene within CPS molecular panel screening.

No Pathogenic DICER1 Gene Variants in a Cohort Study of 28 Children With Congenital Pulmonary Airway Malformation

BACKGROUND

Distinguishing congenital pulmonary airway malformations (CPAMs) from pleuropulmonary blastoma (PPB) can be challenging. Previously diagnosed patients with CPAM may have been misdiagnosed and we may have missed DICER1-associated PPBs, a diagnosis with important clinical implications for patients and their families. To gain insight in potential misdiagnoses, we systematically assessed somatic DICER1 gene mutation status in an unselected, retrospective cohort of patients with a CPAM diagnosis.

METHODS

In the Amsterdam University Medical Center (the Netherlands), it has been standard policy to resect CPAM lesions. We included all consecutive cases of children (age 0-18 years) with a diagnosis of CPAM between 2007 and 2017 at this center. Clinical and radiographic features were reviewed, and DICER1 gene sequencing was performed on DNA retrieved from CPAM tissue samples.

RESULTS

Twenty-eight patients with a surgically removed CPAM were included. CPAM type 1 and type 2 were the most common subtypes (n = 12 and n = 13). For 21 patients a chest CT scan was available for reassessment by two pediatric radiologists. In 9 patients (9/21, 43%) the CPAM subtype scored by the radiologists did not correspond with the subtype given at pathology assessment. No pathogenic mutations and no copy number variations of the DICER1 gene were found in the DNA extracted from CPAM tissue (0/28).

CONCLUSIONS

Our findings suggest that the initial CPAM diagnoses were correct. These findings should be validated through larger studies to draw conclusions regarding whether systematic DICER1 genetic testing is required in children with a pathological confirmed diagnosis of CPAM or not.

LEVEL OF EVIDENCE

Level IV.

DICER1-related Sertoli-Leydig cell tumor and rhabdomyosarcoma: An evolving disease with a challenging clinical course and treatment: A case report

DICER1 syndrome is a rare genetic disorder predisposing young patients to multiple types of cancer. A 17-year-old woman with a history of mixed Sertoli-Leydig cell tumor and juvenile granulosa cell tumor of the left ovary at age 14 presented with a pelvic mass. She underwent fertility preservation cytoreductive surgery and the pathology showed high-grade sarcoma with rhabdomyosarcomatous differentiation. After the surgery, patient received one cycle of chemotherapy but her disease continued to progress. She therefore underwent total hysterectomy, right salpingo-oophorectomy and hyperthermic intraperitoneal chemotherapy followed by consolidation chemotherapy. Magnetic resonance imaging revealed no evidence of the disease before and after the completion of her chemotherapy. Genetic testing confirmed the DICER1 pathogenic variant. However, she presented again with a recurrence of the disease 6 months later and ultimately died of the disease 11 months after the surgery. Our case demonstrates the challenging management of this rare disease in a young patient and the need for new and effective treatments.

Molecular features for timely cancer diagnosis and treatment - tumors of the ovary, fallopian tube and endometrium

Gynecologic pathology has moved, within only a few years, from being a diagnostic area devoid of molecular testing into a diagnostic discipline in which such analyses are becoming routine. The direct relevance of molecular characterization to the choice of treatment of patients with carcinomas originating in both the uterus and adnexae makes it likely that such testing will only expand along with our understanding of the molecular make-up of these tumors. As a consequence, gynecologic pathologists have become an integral part of patient management, rather than lab personnel providing external services.In parallel, molecular testing is expanding as a tool for diagnosing rare tumors affecting these organs, including soft tissue tumors, sex cord-stromal tumors and germ cell tumors, as well as other rare entities. Increased knowledge in this area bears directly on the ability to diagnose these tumors in a reproducible manner, as well as recognize and consult on genetic diseases. Hopefully, despite the inherent difficulty in studying rare cancers, it will also translate into new therapeutic options for the malignant ones among these rare cancers.

Molecular pathology of endocrine gland tumors: genetic alterations and clinicopathologic relevance

Tumors of the endocrine glands are common. Knowledge of their molecular pathology has greatly advanced in the recent past. This review covers the main molecular alterations of tumors of the anterior pituitary, thyroid and parathyroid glands, adrenal cortex, and adrenal medulla and paraganglia. All endocrine gland tumors enjoy a robust correlation between genotype and phenotype. High-throughput molecular analysis demonstrates that endocrine gland tumors can be grouped into molecular groups that are relevant from both pathologic and clinical point of views. In this review, genetic alterations have been discussed and tabulated with respect to their molecular pathogenetic role and clinicopathologic implications, addressing the use of molecular biomarkers for the purpose of diagnosis and prognosis and predicting response to molecular therapy. Hereditary conditions that play a key role in determining predisposition to many types of endocrine tumors are also discussed.

Expanding Our Knowledge of DICER1 Gene Alterations and Their Role in Thyroid Diseases

Mutations in DICER1, a gene involved in RNA interference, have been associated with a wide range of multi-organ neoplastic and non-neoplastic conditions. Historically known for its association with pleuropulmonary blastoma, DICER1 syndrome has received more attention due to the association with newly discovered diseases and tumors. Recent studies evaluating DICER1 mutations and DICER1-driven thyroid disease in both pediatric and adult thyroid nodules revealed thyroid disease as the most common manifestation of DICER1 mutations. This study undertakes a comprehensive investigation into DICER1 mutations, focusing on their role in thyroid diseases. Specific attention was given to thyroid follicular nodular disease and differentiated thyroid carcinomas in infancy as highly indicative of germline DICER1 mutation or DICER1 syndrome. Additionally, poorly differentiated thyroid carcinoma and thyroblastoma were identified as potential indicators of somatic DICER1 mutations. Recognizing these manifestations should prompt clinicians to expedite genetic evaluation for this neoplastic syndrome and classify these patients as high risk for additional multi-organ malignancies. This study comprehensively synthesizes the current knowledge surrounding this genetically associated entity, providing intricate details on histologic findings to facilitate its diagnosis.

The Enrichment of miRNA-Targeted mRNAs in Translationally Less Active over More Active Polysomes

miRNAs moderately inhibit the translation and enhance the degradation of their target mRNAs via cognate binding sites located predominantly in the 3'-untranslated regions (UTR). Paradoxically, miRNA targets are also polysome-associated. We studied the polysome association by the comparative translationally less-active light- and more-active heavy-polysome profiling of a wild type (WT) human cell line and its isogenic mutant (MT) with a disrupted DICER1 gene and, thus, mature miRNA production. As expected, the open reading frame (ORF) length is a major determinant of light- to heavy-polysome mRNA abundance ratios, but is rendered less powerful in WT than in MT cells by miRNA-regulatory activities. We also observed that miRNAs tend to target mRNAs with longer ORFs, and that adjusting the mRNA abundance ratio with the ORF length improves its correlation with the 3'-UTR miRNA-binding-site count. In WT cells, miRNA-targeted mRNAs exhibit higher abundance in light relative to heavy polysomes, i.e., light-polysome enrichment. In MT cells, the DICER1 disruption not only significantly abrogated the light-polysome enrichment, but also narrowed the mRNA abundance ratio value range. Additionally, the abrogation of the enrichment due to the DICER1 gene disruption, i.e., the decreases of the ORF-length-adjusted mRNA abundance ratio from WT to MT cells, exhibits a nearly perfect linear correlation with the 3'-UTR binding-site count. Transcription factors and protein kinases are the top two most enriched mRNA groups. Taken together, the results provide evidence for the light-polysome enrichment of miRNA-targeted mRNAs to reconcile polysome association and moderate translation inhibition, and that ORF length is an important, though currently under-appreciated, transcriptome regulation parameter.

Relevance of Molecular Pathology for the Diagnosis of Sex Cord-Stromal Tumors of the Ovary: A Narrative Review

Ovarian sex cord-stromal tumors (SCSTs) account for 8% of all primary ovarian neo-plasms. Accurate diagnosis is crucial since each subtype has a specific prognostic and treatment. Apart from fibrosarcomas, stromal tumors are benign while sex cord tumors may recur, sometimes with a significant time to relapse. Although the diagnosis based on morphology is straightforward, in some cases the distinction between stromal tumors and sex cord tumors may be tricky. Indeed, the immunophenotype is usually nonspecific between stromal tumors and sex cord tumors. Therefore, molecular pathology plays an important role in the diagnosis of such entities, with pathognomonic or recurrent alterations, such as FOXL2 variants in adult granulosa cell tumors. In addition, these neoplasms may be associated with genetic syndromes, such as Peutz-Jeghers syndrome for sex cord tumors with annular tubules, and DICER1 syndrome for Sertoli-Leydig cell tumors (SLCTs), for which the pathologist may be in the front line of syndromic suspicion. Molecular pathology of SCST is also relevant for patient prognosis and management. For instance, the DICER1 variant is associated with moderately to poorly differentiated SLCTS and a poorer prognosis. The present review summarizes the histomolecular criteria useful for the diagnosis of SCST, using recent molecular data from the literature.