Anaplastic sarcoma of the kidney (DICER1-sarcoma of the kidney): A report from the International Pleuropulmonary Blastoma/DICER1 Registry.

BACKGROUND: Anaplastic sarcoma of the kidney (ASK) is a DICER1-related neoplasm first identified as a distinctive tumor type through the evaluation of unusual cases of putative anaplastic Wilms tumors. Subsequent case reports identified the presence of biallelic DICER1 variants as well as progression from cystic nephroma, a benign DICER1-related neoplasm. Despite increasing recognition of ASK as a distinct entity, the optimal treatment remains unclear. METHODS: Individuals with known or suspected DICER1-related tumors including ASK were enrolled in the International Pleuropulmonary Blastoma/DICER1 Registry. Additionally, a comprehensive review of reported cases of ASK was undertaken, and data were aggregated for analysis with the aim to identify prognostic factors and clinical characteristics to guide decisions regarding genetic testing, treatment, and surveillance. RESULTS: Ten cases of ASK were identified in the Registry along with 37 previously published cases. Staging data, per Children's Oncology Group guidelines, was available for 40 patients: 13 were stage I, 12 were stage II, 10 were stage III, and five were stage IV. Outcome data were available for 37 patients. Most (38 of 46) patients received upfront chemotherapy and 14 patients received upfront radiation. Two-year event-free survival (EFS) for stage I-II ASK was 81.8% (95% confidence interval [CI]: 67.2%-99.6%), compared with 46.6% EFS (95% CI: 24.7%-87.8%) for stage III-IV (p = .07). Two-year overall survival (OS) for stage I-II ASK was 88.9% (95% CI: 75.5%-100.0%), compared with 70.0% (95% CI: 46.7%-100.0%) for stage III-IV (p = .20). Chemotherapy was associated with improved EFS and OS with hazard ratios of 0.09 (95% CI: 0.02-0.31) and 0.08 (95% CI: 0.02-0.42), respectively. CONCLUSION: ASK is a rare DICER1-related renal neoplasm. In the current report, we identify clinical and treatment-related factors associated with outcome including the importance of chemotherapy in treating ASK. Ongoing data collection and genomic analysis are indicated to optimize outcomes for children and adults with these rare tumors.

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.

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.

Type I and Ir pleuropulmonary blastoma (PPB): A report from the International PPB/DICER1 Registry.

BACKGROUND: Pleuropulmonary blastoma (PPB) is the most common lung cancer of infancy and early childhood. Type I PPB is a purely cystic lesion that has a microscopic population of primitive small cells with or without rhabdomyoblastic features and may progress to type II or III PPB, whereas type Ir lacks primitive small cells. METHODS: Children with suspected PPB were enrolled in the International PPB/DICER1 Registry. Pathology was centrally reviewed, and follow-up was ascertained annually. RESULTS: Between 2006 and 2022, 205 children had centrally reviewed type I or Ir PPB; 39% of children with type I and 5% of children with type Ir PPB received chemotherapy. Outcomes were favorable, although 11 children (nine with type I and two with type Ir PPB) experienced progression to type II/III (n = 8) or regrowth of type I PPB at the surgical site (n = 3), none of whom received chemotherapy before progression. Age and cyst size in combination were more suitable than either factor alone in predicting whether a particular lesion was type I or Ir PPB. CONCLUSIONS: For young children with type I PPB, outcomes are favorable, but complete resection is indicated because of the risk for progression. Chemotherapy may be useful in a subset of children at increased risk for recurrence/progression. Efforts to risk stratify children with type I PPB to optimize outcomes while reducing treatment-related side effects are underway.

Outcomes for Children With Type II and Type III Pleuropulmonary Blastoma Following Chemotherapy: A Report From the International PPB/DICER1 Registry.

PURPOSE: Pleuropulmonary blastoma (PPB) is the most common primary lung neoplasm of infancy and early childhood. Type II and type III PPB have historically been associated with a poor prognosis. METHODS: Patients with known or suspected PPB were enrolled in the International PPB/DICER1 Registry. Medical records were abstracted with follow-up ascertained annually. All PPB diagnoses were confirmed by central pathology review. Beginning in 2007, the IVADo regimen (ifosfamide, vincristine, actinomycin-D, and doxorubicin) was recommended as a potential treatment regimen for children with type II and type III PPB. This regimen was compared with a historical control cohort. RESULTS: From 1987 to 2021, 314 children with centrally confirmed type II and type III PPB who received upfront chemotherapy were enrolled; 132 children (75 with type II and 57 with type III) received IVADo chemotherapy. Adjusted analyses suggest improved overall survival for children treated with IVADo in comparison with historical controls with an estimated hazard ratio of 0.65 (95% CI, 0.39 to 1.08). Compared with localized disease, distant metastasis at diagnosis was associated with worse PPB event-free survival and overall survival with hazard ratio of 4.23 (95% CI, 2.42 to 7.38) and 4.69 (95% CI, 2.50 to 8.80), respectively. CONCLUSION: The use of IVADo in children with type II and type III PPB resulted in similar-to-improved outcomes compared with historical controls. Inferior outcomes with metastatic disease suggest the need for novel therapies. This large cohort of uniformly treated children with advanced PPB serves as a benchmark for future multicenter therapeutic studies for this rare pediatric tumor.

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.

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.

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.

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.

Lack of pathogenic germline DICER1 variants in males with testicular germ-cell tumors.

BACKGROUND: Several studies have reported conflicting evidence on the inclusion of testicular germ cell tumors (TGCT) in the DICER1 tumor-predisposition phenotype. We evaluated the relationship between DICER1 and TGCT by reviewing scrotal ultrasounds of males with pathogenic germline variants in DICER1 and queried exome data from TGCT-affected men for DICER1 variants. METHODOLOGY: Fifty-four male DICER1-carriers and family controls (n=41) enrolled in the National Cancer Institute (NCI) DICER1 Natural History Study were offered scrotal ultrasounds. These studies were examined by a single radiologist for abnormalities. In parallel, DICER1 variants from two large exome-sequenced TGCT cohorts were extracted. We used previously published AMG-AMP criteria to characterize rare DICER1 variants. RESULTS: There was no observed difference in frequency of testicular cystic structures in DICER1-carriers versus controls. DICER1 variation was not associated with TGCT in the NCI DICER1-carriers. In 1,264 exome-sequenced men with TGCT, none harbored ClinVar- or InterVar-determined pathogenic or likely pathogenic variants in DICER1. Three DICER1 variants of uncertain significance (one case and two controls) were predicted "damaging" based on a priori criteria. CONCLUSION: Using two complementary approaches, we found no evidence of an association between pathogenic DICER1 variants and TGCT.

Pleuropulmonary blastoma-like peritoneal sarcoma: a newly described malignancy associated with biallelic DICER1 pathogenic variation.

Since the original description of pathogenic germline DICER1 variation underlying pleuropulmonary blastoma (PPB), the spectrum of extrapulmonary neoplasms known to be associated with DICER1 has continued to expand and now includes tumors of the ovary, thyroid, kidney, eye, and brain among other sites. This report documents our experience with another manifestation: a primitive sarcoma that resembles PPB and DICER1-associated sarcoma of the kidney. These tumors are distinguished by their unusual location in the peritoneal cavity, associated with visceral and/or parietal mesothelium. A total of seven cases were identified through pathology review in children presenting at a median age of 13 years (range 3-14 years). Primary sites of origin included the fallopian tube (four cases), serosal surface of the colon (one case), and pelvic sidewall (two cases). One case had pathologic features of type I PPB, another type Ir (regressed) PPB, and the remaining five had features of type II or III PPB with a mixed primitive sarcomatous pattern with or without cystic elements. All had a pathogenic DICER1 variation identified in germline and/or tumor DNA. PPB-like peritoneal tumors represent a newly described manifestation of DICER1 pathogenic variation whose pathologic features are also recapitulated in DICER1-related renal sarcoma, cervical embryonal rhabdomyosarcoma, and some Sertoli-Leydig cell tumors with heterologous elements. Tumors arising from the fallopian tube or elsewhere in the abdomen/pelvis, especially those with heterogeneous rhabdomyosarcomatous and/or cartilaginous differentiation, should prompt consideration of germline and tumor DICER1 testing.

Nasal chondromesenchymal hamartomas in a cohort with pathogenic germline variation in DICER1.

BACKGROUND: Nasal chondromesenchymal hamartomas are benign, rare nasal tumors associated with DICER1 pathogenic germline variation. They can be locally destructive and recurrent if not completely resected. METHODOLOGY: In this single-center, case-control study, otorhinolaryngology evaluations and review of systems questionnaires of DICER1-carriers and controls enrolled in the DICER1 Natural History Study at the National Cancer Institute were collected. Review of these medical records were analyzed to determine if DICER1-carriers experienced different sinonasal clinical manifestations compared to controls. Additionally, the number of diagnoses of nasal chondromesenchymal hamartoma cases in the NCI DICER1 study was compared against the total person years of observation of DICER1-carriers in the study to determine the total number of cases per person-years of observation. Lastly, both the NCI DICER1 study and the International Pleuropulmonary Blastoma/DICER1 Registry were queried for unpublished cases of nasal chondromesenchymal hamartomas. RESULTS: There were no clinical differences in sinonasal symptomatology between DICER1-carriers and control patients seen in the ENT clinic. We observed of two cases of nasal chondromesenchymal hamartoma in a total of 555 person-years of monitoring DICER1-carriers. We include six unpublished nasal chondromesenchymal hamartoma cases. When combined with a comprehensive literature review, 38% of nasal chondromesenchymal hamartoma cases had at least one additional DICER1-associated tumor and 24% of the NCMH were found in the ethmoid sinus, the most commonly involved paranasal sinus. CONCLUSIONS: We quantify the risk of developing nasal chondromesenchymal hamartomas in our cohort of 236 DICER1-carriers, report six unpublished cases, and provide an updated review of the literature.

Presacral malignant teratoid neoplasm in association with pathogenic DICER1 variation.

We report two malignant sacrococcygeal tumors in infants that were associated with pathogenic DICER1 variation. These tumors were composed of primitive neuroepithelium, embryonal rhabdomyosarcoma, and cartilage and initially diagnosed as immature teratomas. One child developed intracranial metastasis and died. The second child underwent surgery and chemotherapy and achieved complete remission. This child subsequently developed five additional DICER1-associated neoplasms by age nine. Genetic analysis revealed that both tumors harbored biallelic pathogenic DICER1 variation. We believe these cases represent another novel subtype of DICER1-associated tumor. This new entity, which we propose to call DICER1-associated presacral malignant teratoid neoplasm, may be difficult initially to distinguish from immature teratoma, but recognizing it as an entity can prompt appropriate classification as an aggressive malignancy and facilitate appropriate genetic counseling, DICER1 germline variant testing, screening, and education.

Neoplasm Risk Among Individuals With a Pathogenic Germline Variant in DICER1.

PURPOSE: DICER1 syndrome is an autosomal-dominant, pleiotropic tumor-predisposition disorder caused by pathogenic germline variants in DICER1. We sought to quantify risk, hazard rates, and the probability of neoplasm incidence accounting for competing risks ("cumulative incidence") of neoplasms (benign and malignant) and standardized incidence ratios for malignant tumors in individuals with DICER1 pathogenic variation. PATIENTS AND METHODS: We combined data from three large cohorts of patients who carry germline pathogenic variation in DICER1. To reduce ascertainment bias, we distinguished probands from nonprobands. Neoplasm diagnoses were confirmed by review of pathology reports and/or central review of surgical pathology materials. Standardized cancer incidence ratios were determined relative to the SEER program, which does not capture all DICER1-associated neoplasms. For all malignancies and benign tumors ("neoplasms," excluding type Ir pleuropulmonary blastoma and thyroid nodules), we used the Kaplan-Meier method and nonparametric cumulative incidence curves to estimate neoplasm-free survival. RESULTS: We calculated the age at first neoplasm diagnosis (systematically ascertained cancers plus DICER1-associated neoplasms pleuropulmonary blastoma, cystic nephroma, and nasal chondromesenchymal hamartoma) in 102 female and male nonproband DICER1 carriers. By age 10 years, 5.3% (95% CI, 0.6% to 9.7%) of nonproband DICER1 carriers had developed a neoplasm (females, 4.0%; males, 6.6%). By age 50 years, 19.3% (95% CI, 8.4% to 29.0%) of nonprobands had developed a neoplasm (females, 26.5%; males, 10.2%). After age 10 years, female risk was elevated compared with male risk. Standardized cancer incidence ratio analysis of 102 nonproband DICER1 carriers, which represented 3,344 person-years of observation, showed significant cancer excesses overall, particularly of gynecologic and thyroid cancers. CONCLUSION: This work provides the first quantitative analysis of site-specific neoplasm risk and excess malignancy risk in 102 systematically characterized nonproband DICER1 carriers. Our findings inform DICER1 syndrome phenotype, natural history, and genetic counseling.

Structural renal abnormalities in the DICER1 syndrome: a family-based cohort study.

BACKGROUND: The DICER1 syndrome is a tumor-predisposition disorder caused by germline pathogenic variation in DICER1 and is associated with cystic nephroma and other renal neoplasms. Dicer1 mouse and rare human DICER1 syndrome case reports describe structural kidney and collecting system anomalies. We investigated renal function and the frequency of structural abnormalities of the kidney and collecting system in individuals with germline loss-of-function variants in DICER1. METHODS: In this family-based cohort study, prospectively ascertained germline DICER1-mutation carriers (DICER1-carriers) and unaffected family controls were evaluated at the National Institutes of Health Clinical Center with renal ultrasound and comprehensive laboratory testing. Two radiologists reviewed the imaging studies from all participants for structural abnormalities, cysts, and tumors. RESULTS: Eighty-nine DICER1-carriers and 61 family controls were studied. Renal cysts were detected in 1/33 DICER1-carrier children without history of cystic nephroma. Similar proportions of adult DICER1-carriers (8/48; 17%) and controls (11/50; 22%) had ultrasound-detected renal cysts (P = 0.504). 8/89 (9%) DICER1-carriers harbored ultrasound-detected structural abnormalities of varying severity within the collecting system or kidney, nephrolithiasis, or nephrocalcinosis. None of the family controls (0/61) had similar findings on ultrasound (P = 0.02). No meaningful differences in renal laboratory values between DICER1-carriers and unaffected family controls were observed. CONCLUSIONS: Our report is the first to systematically characterize renal function and anatomy in a large prospective cohort of DICER1-carriers and DICER1-negative family controls. DICER1-carriers may be at increased risk of structural anomalies of the kidney or collecting system. The role for DICER1 in renal morphogenesis merits additional investigation.

DICER1 and Associated Conditions: Identification of At-risk Individuals and Recommended Surveillance Strategies.

Pathogenic germline DICER1 variants cause a hereditary cancer predisposition syndrome with a variety of manifestations. In addition to conferring increased cancer risks for pleuropulmonary blastoma (PPB) and ovarian sex cord-stromal tumors, particularly Sertoli-Leydig cell tumor, individuals with pathogenic germline DICER1 variants may also develop lung cysts, cystic nephroma, renal sarcoma and Wilms tumor, nodular hyperplasia of the thyroid, nasal chondromesenchymal hamartoma, ciliary body medulloepithelioma, genitourinary embryonal rhabdomyosarcoma, and brain tumors including pineoblastoma and pituitary blastoma. In May 2016, the International PPB Registry convened the inaugural International DICER1 Symposium to develop consensus testing and surveillance and treatment recommendations. Attendees from North America, Europe, and Russia provided expert representation from the disciplines of pediatric oncology, endocrinology, genetics, genetic counseling, radiology, pediatric surgery, pathology, and clinical research. Recommendations are provided for genetic testing; prenatal management; and surveillance for DICER1-associated pulmonary, renal, gynecologic, thyroid, ophthalmologic, otolaryngologic, and central nervous system tumors and gastrointestinal polyps. Risk for most DICER1-associated neoplasms is highest in early childhood and decreases in adulthood. Individual and caregiver education and judicious imaging-based surveillance are the primary recommended approaches. These testing and surveillance recommendations reflect a consensus of expert opinion and current literature. As DICER1 research expands, guidelines for screening and treatment will continue to be updated. Clin Cancer Res; 24(10); 2251-61. ©2018 AACR.

DICER1-related Sertoli-Leydig cell tumor and gynandroblastoma: Clinical and genetic findings from the International Ovarian and Testicular Stromal Tumor Registry.

BACKGROUND: Ovarian sex cord-stromal tumors (OSCST) include juvenile granulosa cell tumors (JGCT), Sertoli-Leydig cell tumor (SLCT) and gynandroblastoma (GAB) among others. These ovarian sex cord-stromal tumors as well as other tumors including pleuropulmonary blastoma (PPB) may be associated with DICER1 mutations. We sought to describe the clinical and genetic findings from the first 107 individuals enrolled in the International Ovarian and Testicular Stromal Tumor Registry. METHODS: Medical and family history were obtained for individuals consecutively enrolled in the International Ovarian and Testicular Stromal Tumor Registry. Pathology was centrally reviewed. DICER1 sequencing was performed on blood and tumor tissue. RESULTS: Of the 107 participants, 49 had SLCT, 25 had JGCT and 5 had GAB. Nearly all (36/37) SLCTs and 4/4 GAB tested had a DICER1 mutation in an RNase IIIb domain hotspot; approximately half of these individuals had a predisposing germline DICER1 mutation. Metachronous SLCTs were seen in 3 individuals with germline DICER1 mutations. Other DICER1-associated conditions were seen in 19% of patients with SLCT or GAB. Three children of women with SLCT were diagnosed with PPB based on genetic testing and clinical screening during the course of this study. All were diagnosed with PPB in its earliest and most curable form (Type I), were treated with surgery alone, and are alive without evidence of disease. CONCLUSIONS: Recognition of the distinct genetic basis for a group of these tumors improves precise classification in difficult cases and promotes mutation-based screening and early detection.

Quantification of Thyroid Cancer and Multinodular Goiter Risk in the DICER1 Syndrome: A Family-Based Cohort Study.

Context: The risk of thyroid cancer and multinodular goiter (MNG) in DICER1 syndrome, a rare tumor-predisposition disorder, is unknown. Objective: To quantify the risk of thyroid cancer and MNG in individuals with DICER1 syndrome. Design: Family-based cohort study. Setting: National Institutes of Health (NIH) Clinical Center (CC). Participants: The National Cancer Institute DICER1 syndrome cohort included 145 individuals with a DICER1 germline mutation and 135 family controls from 48 families. Interventions: Each individual completed a detailed medical history questionnaire. A subset underwent a 3-day evaluation at the NIH CC. Main Outcome Measures: The cumulative incidence of MNG (or thyroidectomy) was quantified using the complement of the Kaplan-Meier product limit estimator. We compared the observed number of thyroid cancers in the NCI DICER1 cohort with matched data from the Surveillance, Epidemiology, and End Results (SEER) Program. We performed germline and somatic (thyroid cancer, MNG) DICER1 sequencing. Results: By the age of 40 years, the cumulative incidence of MNG or thyroidectomy was 75% in women and 17% in men with DICER1 syndrome compared with 8% of control women (P < 0.001) and 0% of control men (P = 0.0096). During 3937 person-years of observation, individuals with DICER1 syndrome had a 16-fold increased risk of thyroid cancer (95% confidence interval, 4.3 to 41; P < 0.05) compared with the SEER rates. Of 19 MNG nodules and 3 thyroid cancers, 16 (84%) and 3 (100%), respectively, harbored germline and somatic pathogenic DICER1 mutations. Conclusions: We propose a model of thyroid carcinogenesis in DICER1 syndrome. Early-onset, familial, or male MNG should prompt consideration of the presence of DICER1 syndrome.

Macrocephaly associated with the DICER1 syndrome.

PURPOSE: Germ-line mutations in DICER1 increase the risk of various tumors, including pleuropulmonary blastoma. Macrocephaly and symmetric overgrowth have been reported in some, but not all, patients with mosaic DICER1 RNase IIIb mutations. The prevalence of these features in individuals with constitutional germ-line DICER1 mutations is unknown. METHODS: We analyzed prospectively collected auxology data from 67 DICER1 mutation carriers and 43 family controls. We assessed differences between groups using an exact test for proportions and generalized estimating equations for continuous dependent variables. RESULTS: Twenty-eight DICER1 mutation carriers (42%) were macrocephalic, and none had an occipitofrontal circumference (OFC) below the third centile, which significantly differed from family controls, of whom five were macrocephalic (12%) and two had OFC below the third centile (5%) (P < 0.001). DICER1 mutation carriers were taller than familial controls after controlling for gender (P = 0.048), but similar proportions of both groups were above the 97th centile of population norms. Head circumference remained increased after adjusting for differences in height. CONCLUSION: For the first time, we establish macrocephaly as a common finding in the DICER1 syndrome. Like some other tumor-predisposition disorders, macrocephaly may be a useful, albeit a subtle, clinical clue to the DICER1 syndrome diagnosis.Genet Med 19 2, 244-248.