Pleuropulmonary blastoma: a marker for familial disease

Molecular Alterations in Pediatric Solid Tumors

Pediatric tumors can be divided into hematologic malignancies, central nervous system tumors, and extracranial solid tumors of bone, soft tissue, or other organ systems. Molecular alterations that impact diagnosis, prognosis, treatment, and familial cancer risk have been described in many pediatric solid tumors. In addition to providing a concise summary of clinically relevant molecular alterations in extracranial pediatric solid tumors, this review discusses conventional and next-generation sequencing-based molecular techniques, relevant tumor predisposition syndromes, and the increasing integration of molecular data into the practice of diagnostic pathology for children with solid tumors.

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.

DICER1-associated central nervous system sarcoma: A comprehensive clinical and genomic characterization of case series of young adult patients

Background

DICER1 alterations are associated with intracranial tumors in the pediatric population, including pineoblastoma, pituitary blastoma, and the recently described "primary DICER1-associated CNS sarcoma" (DCS). DCS is an extremely aggressive tumor with a distinct methylation signature and a high frequency of co-occurring mutations. However, little is known about its treatment approach and the genomic changes occurring after exposure to chemoradiotherapy.

Methods

We collected clinical, histological, and molecular data from eight young adults with DCS. Genomic analysis was performed by Next-generation Sequencing (NGS). Subsequently, an additional germline variants analysis was completed. In addition, an NGS analysis on post-progression tumor tissue or liquid biopsy was performed when available. Multiple clinicopathological characteristics, treatment variables, and survival outcomes were assessed.

Results

Median age was 20 years. Most lesions were supratentorial. Histology was classified as fusiform cell sarcomas (50%), undifferentiated (unclassified) sarcoma (37.5%), and chondrosarcoma (12.5%). Germline pathogenic DICER1 variants were present in two patients, 75% of cases had more than one somatic alteration in DICER1, and the most frequent commutation was TP53. Seven patients were treated with surgery, Ifosfamide, Cisplatin, and Etoposide (ICE) chemotherapy and radiotherapy. The objective response was 75%, and the median time to progression (TTP) was 14.5 months. At progression, the most common mutations were in KRAS and NF1. Overall survival was 30.8 months.

Conclusions

DCS is an aggressive tumor with limited therapeutic options that requires a comprehensive diagnostic approach, including molecular characterization. Most cases had mutations in TP53, NF1, and PTEN, and most alterations at progression were related to MAPK, RAS and PI3K signaling pathways.

All pineal tumors expressing germ cell tumor markers are not necessarily germ cell tumors: histopathological and molecular study of a midline primary intracranial sarcoma DICER1-mutant

Primary intracranial sarcoma DICER1-mutant is a rare and newly recognized tumor type introduced in the 2021 WHO Classification of Central Nervous System Tumors. It is defined as a spindle cell sarcoma dysplaying eosinophilic intracytoplasmic globules, myogenic differentiation, and DICER1 gene mutation, either somatic or germline. Most reported cases were hemispheric except one, recently described in the pineal region. Here, we report the case of a 12 year-old boy with a pineally located tumor. Despite midline location, poorly differenciated morphology and germ cell marker expression, the association of DICER1 and NF1 hotspot mutations and a specific DNA methylation signature finally lead to the diagnosis of primary intracranial sarcoma DICER1-mutant instead of germ cell tumor. Furthermore, our molecular exploratory results involved a pathway, which was not previously evidenced in those DICER1 mutated cerebral sarcoma that is the canonical Wnt signaling driving likely a part of oncogenesis in this newly described pineal entity.

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.

Congenital midline spinal hamartoma in an infant with DICER1 syndrome: A case report

Congenital spinal hamartomas are rare benign tumors. They are mostly seen in infants and are typically asymptomatic at presentation. Spinal hamartomas have not been associated with any known cancer predisposition syndrome. DICER1 syndrome is a well-characterized cancer predisposition syndrome caused by a germline mutation in the DICER1 gene, which shows variable expressivity. To our knowledge, spinal hamartoma has never been described in individuals with DICER1 syndrome. Here, we describe a rare association of congenital spinal hamartoma and DICER1 syndrome in a 5-week-old infant, with molecular findings suggestive of the implication of DICER1 in the pathogenesis of this tumor.

PUMILIO competes with AUF1 to control DICER1 RNA levels and miRNA processing

DICER1 syndrome is a cancer pre-disposition disorder caused by mutations that disrupt the function of DICER1 in miRNA processing. Studying the molecular, cellular and oncogenic effects of these mutations can reveal novel mechanisms that control cell homeostasis and tumor biology. Here, we conduct the first analysis of pathogenic DICER1 syndrome allele from the DICER1 3'UTR. We find that the DICER1 syndrome allele, rs1252940486, abolishes interaction with the PUMILIO RNA binding protein with the DICER1 3'UTR, resulting in the degradation of the DICER1 mRNA by AUF1. This single mutational event leads to diminished DICER1 mRNA and protein levels, and widespread reprogramming of miRNA networks. The in-depth characterization of the rs1252940486 DICER1 allele, reveals important post-transcriptional regulatory events that control DICER1 levels.

Langerhans cell histiocytosis and associated malignancies: A retrospective analysis of 270 patients

PURPOSE

The frequency of Langerhans cell histiocytosis (LCH) and associated malignancies (AM) is greater than statistically expected. Here, we analyze LCH-AM co-occurrence in both children and adults.

METHODS

Between 1991 and 2015, data were collected by regular questionnaires to members of the Histiocyte Society and searches in PubMed and Abstract Books. Patients were grouped by age at LCH diagnosis (≤ and >18 years), and types and timing of AM occurrence were plotted with respect to the LCH diagnosis. For the statistical analysis, only the first AM were considered.

RESULTS

A total of 285 LCH-AM in 270 patients were identified, 116 (43%) ≤ 18 years, and 154 (57%) >18 years. In childhood LCH-AM pairs, leukemias and myeloproliferative disorders (n = 58; 50.0%) prevailed over solid tumors (n = 43; 37.1%) and lymphoma (n = 15; 12.9%). In adults, solid tumors were reported in 61 patients (39.6%), lymphoma, and leukemias and myeloproliferative disorders in 56 (36.4%) and 37 (24.0%) patients, respectively. In most children, AM followed LCH (n = 69, 59.5%), whereas in adults, LCH and AM occurred concurrently in 69 patients (44.8%). In children, T-lineage acute lymphoblastic leukemia (ALL) and promyelocytic acute myeloid leukemia (AML) and retinoblastoma were over-represented and thyroid carcinoma in adults.

CONCLUSIONS

The largest collection of data on LCH-AM to date clearly indicates inherent relationships between specific types of AM and LCH, which may be due to therapy effects, clonal evolution, and germ-line predisposition, respectively. Prospective thorough genetic analysis is warranted and will hopefully shed light on the association of LCH and second neoplasms.

A primary DICER1-sarcoma with KRAS and TP53 mutations in a child with suspected ECCL

A child had been followed since infancy by our multi-disciplinary neuro-oncology clinic with annual magnetic resonance imaging (MRI) under the presumed diagnosis of encephalocraniocutaneous lipomatosis (ECCL), with clinical features including nevus psiloliparus, scalp lipoma, nodular skin tag on and coloboma of the eyelid, cortical atrophy and meningeal angiomatosis. At the age of 4, she was found to have a large temporoparietal lesion causing elevated intracranial pressure requiring surgical resection. Histopathological exam of the tumor was suggestive of an intracranial sarcoma. Sequencing analysis of the tumor revealed mutations in DICER1, KRAS and TP53. Subsequent germline testing confirmed DICER1 syndrome and revealed an insignificant FGFR1 variant at a low frequency. Methylation profile of the tumor showed the tumor clustered most closely with sarcoma (rhabdomyosarcoma-like), confirming this tumor to be a primary DICER1-sarcoma. Compared to the previously reported cases, our unique case of primary DICER1-sarcoma also demonstrated neurofilament and chromogranin positivity, and genomic instability with loss of chromosome 4p, 4q, 8p, 11p, and 19p, as well as gains in chromosome 7p, 9p, 9q, 13q, and 15q on copy variant analysis. The detailed sequencing and methylation information discovered in this unique case of DICER1-sarcoma will hopefully help further our understanding of this rare and emerging entity.

Proceedings of the North American Society of Head and Neck Pathology, Los Angeles, CA, March 20, 2022: DICER1-Related Thyroid Tumors

DICER1 syndrome is an autosomal dominant tumor predisposition syndrome caused by germline DICER1 mutations. In the thyroid, DICER1 syndrome is associated with early-onset multinodular goiter and thyroid carcinomas. Subsequent studies have shown that somatic DICER1 mutations, though rare, can occur in follicular-patterned thyroid tumors, such as follicular adenomas and follicular thyroid carcinomas, with a higher rate seen in pediatric follicular thyroid carcinomas and in follicular thyroid carcinomas with a macrofollicular architecture. Somatic DICER1 mutations have also been reported in pediatric papillary thyroid carcinomas lacking other alterations typically associated with thyroid tumorigenesis. Although thyroid carcinomas with underlying DICER1 mutations are usually indolent, recent studies have shown that pediatric poorly differentiated thyroid carcinoma and thyroblastoma, both aggressive tumors, also harbor DICER1 mutations. This review will discuss mechanisms of DICER1 tumorigenesis and describe thyroid tumors associated with germline and somatic DICER1 mutations.

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

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

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

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

Pleuropulmonary blastoma: A report of three cases and review of literature

Pleuropulmonary blastoma is a rare and highly aggressive pulmonary malignancy in children. Clinically, the malignancy is often mistaken for symptoms of respiratory tract infection or pneumothorax. The neoplasm is histologically characterized by primitive blastema and a malignant mesenchymal stroma that demonstrates multidirectional differentiation. The patients with PPB are managed by multimodal therapy. We present a report of 3 cases of histopathologically diagnosed pleuropulmonary blastoma. The patients presented with chief complaints of difficulty in breathing, cough, fever and chest pain. Radiographs of the patients showed partial to complete opacification of hemithorax. Contrast enhanced computed tomography scans revealed large well defined heterogenously enhancing solid mass lesions in the hemithorax. Knowledge of types, imaging findings, staging and association with other tumors is crucial for correct diagnosis of pleuropulmonary blastoma and subsequent adequate management.

Type II pleuropulmonary blastoma in a 3-years-old female with dyspnea: a case report and review of literature

Pleuropulmonary blastoma (PPB) is a rare but aggressive pediatric tumor originates from either lung or pleura. It was recently linked to the DICER I mutation as a part of predisposition syndrome for different type of tumor. It is characterized histologically by a primitive, variably mixed blastomatous and sarcomatous tissue. PPB is classified into four subtypes: cystic (type I and type Ir); cystic and solid (type II); solid (type III). PPB has no characteristic imaging findings. Integrated imaging can help to make a differential diagnosis and to recognize the subtypes in order to set up therapy. An early recognition and differentiation from congenital airway malformations and other benign cysts are very important. The treatment consists in a multimodal therapy including surgery and chemoterapy. We report a case of 3 years old female admitted at our hospital with fever, non productive cough and dyspnea, who was diagnosed with type II PPB.

Molecular Alterations in Pediatric Solid Tumors

Pediatric tumors can be divided into hematologic malignancies, central nervous system tumors, and extracranial solid tumors of bone, soft tissue, or other organ systems. Molecular alterations that impact diagnosis, prognosis, treatment, and familial cancer risk have been described in many pediatric solid tumors. In addition to providing a concise summary of clinically relevant molecular alterations in extracranial pediatric solid tumors, this review discusses conventional and next-generation sequencing-based molecular techniques, relevant tumor predisposition syndromes, and the increasing integration of molecular data into the practice of diagnostic pathology for children with solid tumors.

Molecular characterization of DICER1-mutated pituitary blastoma

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

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.

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

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

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

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

DICER1 Syndrome and Cancer Predisposition: From a Rare Pediatric Tumor to Lifetime Risk

DICER1 syndrome is a rare genetic condition predisposing to hereditary cancer and caused by variants in the DICER1 gene. The risk to present a neoplasm before the age of 10 years is 5.3 and 31.5% before the age of 60. DICER1 variants have been associated with a syndrome involving familial pleuropulmonary blastoma (PPB), a rare malignant tumor of the lung, which occurs primarily in children under the age of 6 years and represents the most common life-threatening manifestation of DICER1 syndrome. Type I, II, III, and Ir (type I regressed) PPB are reported with a 5-year overall survival ranging from 53 to 100% (for type Ir). DICER1 gene should be screened in all patients with PPB and considered in other tumors mainly in thyroid neoplasms (multinodular goiter, thyroid cancer, adenomas), ovarian tumors (Sertoli-Leydig cell tumor, sarcoma, and gynandroblastoma), and cystic nephroma. A prompt identification of this syndrome is necessary to plan a correct follow-up and screening during lifetime.

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.

Pediatric Renal Tumors: Updates in the Molecular Era

Molecular characterization has led to advances in the understanding of pediatric renal tumors, including the association of pediatric cystic nephromas with DICER1 tumor syndrome, the metanephric family of tumors with somatic BRAF mutations, the characterization of ETV6-NTRK3-negative congenital mesoblastic nephromas, the expanded spectrum of gene fusions in translocation renal cell carcinoma, the relationship of clear cell sarcoma of the kidney with other BCOR-altered tumors, and the pathways affected by SMARCB1 alterations in rhabdoid tumors of the kidney. These advances have implications for diagnosis, classification, and treatment of pediatric renal tumors.

DICER1-associated central nervous system sarcoma in children: comprehensive clinicopathologic and genetic analysis of a newly described rare tumor

The spectrum of neoplasms associated with DICER1 variants continues to expand, with the recent addition of primary "DICER1-associated central nervous system sarcoma" (DCS). DCS is a high-grade malignancy predominantly affecting pediatric patients. Six pediatric DCS were identified through a combination of clinical diagnostic studies, archival inquiry, and interinstitutional collaboration. Clinical, histologic, immunohistologic, and molecular features were examined. Genomic findings in the 6 DCS were compared with those in 14 additional DICER1-associated tumors sequenced with the same assay. The six patients presented at ages 3-15 years with CNS tumors located in the temporal (n = 2), parietal (n = 1), fronto-parietal (n = 1), and frontal (n = 2) lobes. All underwent surgical resection. Histologic examination demonstrated high-grade malignant spindle cell tumors with pleuropulmonary blastoma-like embryonic "organoid" features and focal rhabdomyoblastic differentiation; immature cartilage was seen in one case. Immunohistochemically, there was patchy desmin and myogenin staining, and patchy loss of H3K27me3, and within eosinophilic cytoplasmic globules, alfa-fetoprotein staining. Biallelic DICER1 variants were identified in all cases, with germline variants in two of five patients tested. DCS demonstrated genomic alterations enriched for Ras pathway activation and TP53 inactivation. Tumor mutational burden was significantly higher in the 6 DCS tumors than in 14 other DICER1-associated tumors examined (mean 12.9 vs. 6.8 mutations/Mb, p = 0.035). Postoperative care included radiation (n = 5) and chemotherapy (n = 3); at the last follow-up, three patients were alive without DCS, and three had died of disease. Our analysis expands the clinical, histologic, immunohistological, and molecular spectrum of DCS, identifying distinctive features that can aid in the diagnosis, multidisciplinary evaluation, and treatment of DCS.

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.

An update on the central nervous system manifestations of DICER1 syndrome

DICER1 syndrome is a rare tumor predisposition syndrome with manifestations that predominantly affect children and young adults. The syndrome is typically caused by heterozygous germline loss-of-function DICER1 alterations accompanied on the other allele by somatic missense mutations occurring at one of a few mutation hotspots within the sequence encoding the RNase IIIb domain. DICER1 encodes a member of the microRNA biogenesis machinery. The syndrome spectrum is highly pleiotropic and features a unique constellation of benign and malignant neoplastic and dysplastic lesions. Pleuropulmonary blastoma (PPB), the most common primary lung cancer in children, is the hallmark tumor of the syndrome. Other manifestations include ovarian Sertoli-Leydig cell tumor, cystic nephroma arising in childhood, multinodular goiter, thyroid carcinoma, anaplastic sarcoma of the kidney, embryonal rhabdomyosarcoma, and nasal chondromesenchymal hamartoma, in addition to other rare entities. Several central nervous system (CNS) manifestations have also been defined, including metastases of PPB to the cerebrum, pituitary blastoma, pineoblastoma, ciliary body medulloepithelioma, and most recently primary DICER1-associated CNS sarcomas and ETMR-like infantile cerebellar embryonal tumor. Macrocephaly is a recently reported non-neoplastic, haploinsufficient phenotype. In this manuscript, we review the CNS manifestations of DICER1 syndrome.

Primary malignant lung tumors in children: A report from the Australian Childhood Cancer Registry, 1983-2015

Lung cancers in children under the age of 15 are very uncommon, with a scarcity of literature describing patient characteristics and survival. This study assessed first primary malignant cancers occurring in the trachea, bronchus, or lung (International Classification of Diseases for Oncology, 3rd edition [ICD-O-3] codes C33-C34) for the period 1983-2015, using data from the population-based Australian Childhood Cancer Registry. Variables of interest included morphology, sex, age group, and metastatic status at diagnosis. Mode of treatment was also assessed where possible. The Kaplan-Meier method was used to calculate 5-year observed survival. Of the 53 in-scope patients, almost half (n = 23, 43%) were diagnosed with pleuropulmonary blastoma and a further 8 (15%) had a carcinoid tumor. Few of the patients with details available on stage at diagnosis (n = 7 of 43, 16%) presented with metastatic disease. Surgical excision was the most common treatment (30 of 37 children, 81%), with two-thirds (n = 28 of 43, 65%) receiving chemotherapy. Five-year observed survival was estimated to be 74% (95% CI = 61%-85%). Our results represent one of the largest and most complete population-based cohorts of children with primary malignant lung cancers available to date. Detection of childhood lung cancer can be difficult due to the rarity of this disease and symptoms that are typically nonspecific.

Pleuropulmonary blastoma: A report of two cases

Pleuropulmonary blastoma is a rare and aggressive childhood tumor of mesenchymal origin. It has a poor prognosis and mainly classified as cystic (type 1), mixed type (type 2), and solid (type 3). Herein, we present two cases of pleuropulmonary blastoma type 3 presenting with pneumothorax, a rare clinical presentation of pleuropulmonary blastoma, which was successfully treated with surgery.

Imaging of DICER1 syndrome

DICER1 syndrome is a highly pleiotropic tumor predisposition syndrome that has been increasingly recognized in the last 10 years. Diseases in the syndrome result from mutations in both copies of the gene DICER1, a highly conserved gene that is critically implicated in micro-ribonucleic acid (miRNA) biogenesis and hence modulation of messenger RNAs. In general, susceptible individuals carry an inherited germline mutation that disables one copy of DICER1; within tumors, a very characteristic second mutation alters function of the other gene copy. About 20 hamartomatous, hyperplastic or neoplastic conditions comprise DICER1 syndrome. Most are not life-threatening, but some are aggressive malignancies. There are many unaffected carriers because penetrance is generally low; however, clinically occult thyroid nodules and lung cysts are frequent. Rare diseases of early childhood were the first recognized conditions in DICER1 syndrome, while other conditions affect adolescents and adults. The hallmarks of DICER1 syndrome are certain rare tumors including pleuropulmonary blastoma; cystic nephroma; ovarian Sertoli-Leydig cell tumor; sarcomas of the cervix, kidneys and cerebrum; pituitary blastoma; ciliary body medulloepithelioma; and nasal chondromesenchymal hamartoma. Radiologists are often the first practitioners to observe these diverse manifestations and play a primary role in recognizing DICER1 syndrome.

Germline Genetics and Childhood Cancer: Emerging Cancer Predisposition Syndromes and Psychosocial Impacts

PURPOSE OF REVIEW

Germline genetic variants contribute to a substantial proportion of cases of cancer in childhood. The purpose of this review is to describe two emerging pediatric cancer predisposition syndromes, including published surveillance protocols, as well as the psychological impacts related to childhood cancer predisposition.

RECENT FINDINGS

DICER1 syndrome is pleotropic, predisposing to a variety of tumors and likely phenotypically broader than currently realized. Rhabdoid tumor predisposition syndrome carries a risk for development of aggressive malignancies occurring in nearly any tissue. New pediatric hereditary cancer syndromes are likely to be identified as genetic evaluation evolves. Advantages and disadvantages of genetic testing and surveillance protocols need to be discussed with patients and families in a team-based approach, with the input of a genetic counselor holding expertise in pediatric cancer predisposition. Finally, literature on psychosocial impacts of hereditary cancer syndromes in pediatric patients is sparse, necessitating further research.

Current Management of Pleuropulmonary Blastoma: A Surgical Perspective

Pleuropulmonary blastomas (PPB) are pediatric, embryonal cancers of the lung parenchyma and pleural surfaces and are among the most common DICER1-related disorders. These tumors undergo evolution through several forms, allowing division into types I, Ir, II, and III, with correlates to the age of diagnosis and prognosis. We sought to provide a comprehensive review of the relevant literature describing the characteristics of these tumors and their multidisciplinary treatment, with an emphasis on surgical management. We describe the complementary roles of chemotherapy and surgery in the successful management of this disease. We discuss the timing of surgery and options for surgical approaches. We address the differentiation of PPB from congenital pulmonary airway malformation and the role of DICER1 testing for children with pulmonary cysts.

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.

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.

Strong Expression and Amplification of IGF1R in Pleuropulmonary Blastomas

Pleuropulmonary blastoma (PPB) is a rare malignant intrathoracic tumor primarily affecting children under 5 years of age. PPBs are histologically divided into 3 subtypes: Type 1 PPBs are composed of multiple cysts, and type 3 is a solid lesion with a variable morphologic appearance. Type 2 has a mixed morphology consisting of cystic and solid areas. The genetics of PPB are poorly understood. We analyzed 16 cases of the Kiel Paediatric Tumor Registry with the diagnosis of PPB by comparative genomic hybridization and confirmed some genetic changes by fluorescence in situ hybridization. Furthermore, we performed immunohistochemistry to evaluate insulin-like growth factor type 1 (IGF1R) protein expression. Frequent findings by comparative genomic hybridization were losses on 4q, 5q, 9p and gains on chromosome 8, 17, and 20q. Genomic amplification was observed in 5 cases, 4 related to 15q25qter and 1 to 1p. Fluorescence in situ hybridization could confirm 7 gains of chromosome 8 (7/16, 44%) and 4 amplifications of the IGF1R-gene on 15q26 (4/16, 25%). All of the tumors with IGF1R amplification were type 3 PPBs. One of the PPBs with gain of chromosome 8 was a type 2 tumor and 6 tumors were type 3 PPBs. All but one PPB showed an IGF1R expression by immunohistochemistry. In our series of 16 PPBs, 25% of the tumors have an amplification of the IGF1R gene and 44% show a gain of chromosome 8. All of the tumors with IGF1R amplification were PPBs type 3, indicating that it is a later event in tumor progression, while the gain of chromosome 8 was found in both type 2 and type 3 tumors indicating that these changes are probably earlier events in tumor development. Furthermore, the strong IGF1R protein expression could be a possible therapeutic target in refractory chemoresistant PPBs.

Pediatric imaging in DICER1 syndrome

BACKGROUND

DICER1 syndrome, arising from a mutation in the DICER1 gene mapped to chromosome 14q32, is associated with an increased risk of a range of benign and malignant neoplasms.

OBJECTIVE

To determine the spectrum of abnormalities and imaging characteristics in patients with DICER1 syndrome at a tertiary pediatric hospital.

MATERIALS AND METHODS

This retrospective analysis evaluated imaging in patients ≤18 years with DICER1 germline variants between January 2004 and July 2016. An imaging database search including keywords pleuropulmonary blastoma, cystic nephroma, pineoblastoma, embryonal rhabdomyosarcoma, ovarian sex cord-stromal tumor, ovarian Sertoli-Leydig cell tumor and DICER1 syndrome, was cross-referenced against the institutional Cancer Genetics Program database, excluding patients with negative/unknown DICER1 gene testing.

RESULTS

Sixteen patients were included (12 females; mean age at presentation: 4.2 years, range: 14 days to 17 years), with surveillance imaging encompassing the following modalities: chest X-ray and CT; abdominal, pelvic and neck US; and brain and whole-body MRI. Malignant lesions (68.8% of patients) included pleuropulmonary blastoma (5), pineoblastoma (3), ovarian Sertoli-Leydig cell tumor (1), embryonal rhabdomyosarcoma (1) and renal sarcoma (1); benign lesions (37.5% of patients) included thyroid cysts (2), thyroid nodules (2), cystic nephroma (2), renal cysts (1) and pineal cyst (1). A common lesional appearance observed across modalities and organs was defined as the "cracked windshield" sign.

CONCLUSION

The spectrum of DICER1-related tumors and the young age at presentation suggest early surveillance of at-risk patients is critical, while minimizing exposure to ionizing radiation.

Multimorbidity and Genetic Characteristics of DICER1 Syndrome Based on Systematic Review

It has been reported that germline DICER1 mutations correlate with a distinctive human disease syndrome. Many published studies within this field have been conducted based on rare cases. We systematically searched bibliographic databases, including PubMed, Embase, and COSMIC for articles which are related to diseases covered by DICER1 syndrome. The weighted summary of mutation frequencies among patients with pleuropulmonary blastoma (PPB), cystic nephroma (CN), and Sertoli-Leydig cell tumor (SLCT) were calculated. Forty-nine eligible articles were included. In total, 72 cases with multimorbidity of DICER1 syndrome were identified. More females (n=46, 64%) presented with multimorbidity than males (n=18, 25%) and the remaining 8 patients' sex were unknown. Nineteen of 72 patients with multimorbidity suffered from another disease that was not yet included in DICER1 syndrome, which would provide potential phenotypes of DICER1 syndrome. The germline DICER1 mutation frequencies in PPB, CN, and SLCT were 66.9%, 73.2%, and 57.1%, respectively. The somatic DICER1 mutation frequencies of PPB, CN, and SLCT were 92.4%, 87.9%, and 43.3%, respectively. Majority of patients with multimorbidity of DICER1 syndrome were mutation positive individuals so that multimorbidity may suggest the possible germline mutation of these patients and their relatives.

DICER1 mutations in twelve Chinese patients with pleuropulmonary blastoma

Our aim is to examine the impact of DICER1 mutations on the pathogenesis of pleuropulmonary blastoma (PPB) by evaluating the mutation frequency and investigating the family history of Chinese patients with PPB. The family histories of 12 children with PPB recruited consecutively were surveyed. Blood samples from patients and their first-degree relatives were tested for DICER1 mutations. Whole-genome sequencing of blood samples and formalin-fixed and paraffin-embedded (FFPE) tumor tissue was performed in one family with twins. Twelve patients with PPB included six type II and six type III cases. Seven of the 12 patients harbored DICER1 mutations, six of which were frameshift or nonsense mutations. Another case carried a germline DICER1 mutation affecting the splice site. FFPE sample had a nonsense mutation in TDG and missense mutations in DICER1. In addition, two cases with DICER1 mutations were found to have lung cysts preceding the diagnosis of PPB. Furthermore, one patient had a family history remarkable for thyroid diseases. Our results indicate that the germline mutation frequency in Chinese patients with PPB is similar to the ones reported for patients from USA, UK, and Japan. Moreover, our study strongly suggests that investigating the family history and detecting germline DICER1 mutations might be of benefit to increasing awareness and improving the accuracy of the differential diagnosis of PPB from non-malignant lung cysts.

Sequencing of DICER1 in sarcomas identifies biallelic somatic DICER1 mutations in an adult-onset embryonal rhabdomyosarcoma

BACKGROUND

Sarcomas are rare and heterogeneous cancers. We assessed the contribution of DICER1 mutations to sarcoma development.

METHODS

The coding region of DICER1 was sequenced in 67 sarcomas using a custom Fluidigm Access Array. The RNase III domains were Sanger sequenced in six additional sarcomas to identify hotspot DICER1 variants.

RESULTS

The median age of sarcoma diagnosis was 45.7 years (range: 3 months to 87.4 years). A recurrent embryonal rhabdomyosarcoma (ERMS) of the broad ligament, first diagnosed at age 23 years, harboured biallelic pathogenic somatic DICER1 variants (1 truncating and 1 RNase IIIb missense). We identified nine other DICER1 variants. One somatic variant (p.L1070V) identified in a pleomorphic sarcoma and one germline variant (c.2257-7A>G) may be pathogenic, but the others are considered to be benign.

CONCLUSIONS

We show that deleterious DICER1 mutations underlie the genetic basis of only a small fraction of sarcomas, in particular ERMS of the urogenital tract.

A Case Report of Pleuropulmonary Blastoma Presenting as Tension Pneumothorax

Pleuropulmonary blastoma (PPB) is a very rare, highly aggressive, and malignant tumor that originates from either lungs or pleura. It occurs mainly in children aged <5 or 6 years. It has poor prognosis with three different subtypes: cystic (type I), combined cystic and solid (type II), and solid (type III). PPB is treated with aggressive multimodal therapies including surgery and chemotherapy. We present a case of PPB in a 3-year-old girl who presented with tension pneumothorax.

Metachronous Type I pleuropulmonary blastoma and atypical choroid plexus papilloma in a young child

Pleuropulmonary blastoma (PPB) is a rare childhood tumor, often associated with germline DICER1 mutations and a risk for development of other benign and malignant tumors, a constellation termed DICER1 syndrome. A 1-year-old male was diagnosed with Type I PPB and screened regularly thereafter for detection of intrathoracic and intraabdominal disease. Ten months after diagnosis of PPB, he presented with headaches and vomiting. He was diagnosed with atypical choroid plexus papilloma, a lesion not previously reported with PPB. The presence of central nervous system symptoms in patients with PPB or a phenotype suggestive of DICER1 syndrome should prompt early intracranial imaging.

Pulmonary and pleural pathology: Contributions of Dr. Louis "Pepper" Dehner

Dr. Louis Dehner is an internationally renowned surgical pathologist who has published multiple textbooks and has authored or co-authored nearly 400 original articles in the medical literature. While many think of him as a pediatric pathologist, he has contributed to the literature across virtually the entire breadth of surgical pathology, and the lung and pleura is no exception. This review will highlight Dr. Dehner׳s contributions to the pulmonary and pleural pathology literature in the areas of infectious disease, medical lung disease and transplant pathology, and a number of neoplasms of the lung and pleura, with the remainder of this manuscript dedicated to the still evolving story of the pleuropulmonary blastoma as the signature contribution of his long and distinguished career.

Gynecologic Manifestations of the DICER1 Syndrome

Patients with germline DICER1 mutations are at increased risk of developing a wide range of tumors, most of which are relatively rare in the general population. In the gynecologic tract, these include ovarian sex cord-stromal tumors, particularly Sertoli-Leydig cell tumor, and embryonal rhabdomyosarcoma of the cervix. In some cases, these are the sentinel neoplasms. DICER1-associated tumors may have distinctive morphologic appearances that may prompt the pathologist to consider an underlying tumor predisposition syndrome and therefore consideration of genetic evaluation in the patient and her family.

DICER1 pleuropulmonary blastoma familial tumour predisposition syndrome: What the paediatric urologist needs to know

INTRODUCTION

Germline-inactivating DICER1 mutations are responsible of a familial tumour susceptibility syndrome with an increased risk of tumours, mainly pleuropulmonary blastoma (PPB). DICER1 mutations also cause a range of other tumours, some of them in urogenital organs (cystic nephroma [CN], ovarian sex cord-stromal tumours, bladder and cervix embryonal rhabdomyosarcoma [ERMS]).

OBJECTIVE

The aim was to clarify the range of urogenital phenotypes associated with DICER1 mutations and to give practical course of action to paediatric urologist that are exposed to DICER1-related conditions.

STUDY DESIGN

A literature review was performed. Pertinent papers focused on urogenital diseases associated with DICER1 mutations were reviewed.

RESULTS

Seventy per cent of CN have a DICER1 germline mutation. The majority of them (80%) have PPB. Like PPB, CN could undergo a malignant progression to a primitive sarcoma. Some rare cases of Wilms tumours were reported. Regarding gonadal manifestations, sex-cord stromal neoplasia of the ovary, especially Sertoli-Leydig cell tumour (SLCT), is the most frequent tumour associated with DICER1 germline mutation. Germline DICER1 mutations also predispose to uterine cervix and bladder ERMS.

DISCUSSION

The presence of unusual tumours suggesting DICER1 mutations may alert clinicians. The first step is to obtain a complete familial history. The variable clinical presentation and the modest penetrance raise concerns about the appropriateness of genetic testing to patients and their relatives. The education of DICER1 mutations carriers about tumour-related symptoms is consensual. In the first 5 years of life, a yearly chest X-ray and abdominal ultrasound are recommended.

CONCLUSION

The presence of a CN, ovarian SLCT or urogenital ERMS in a child should alert the clinician to the possibility of DICER1 mutation and the associated risk of PPB. Individuals with one of the typical DICER1 conditions should be offered DICER1 analysis. Despite the low penetrance, a genetic counselling and testing should be offered to the family of the affected child.

Insulin-like Growth Factor 2 Gene Expression Molecularly Differentiates Pleuropulmonary Blastoma and Embryonal Rhabdomyosarcoma

The sarcomatous element in pleuropulmonary blastoma (PPB) is often histologically indistinguishable from embryonal rhabdomyosarcoma (ERMS). A diagnosis of PPB is often made after definitive surgical resection based on pathologic features, most notably the presence of hamartomatous pulmonary elements. Samples from seven PPB patients were obtained from the rhabdomyosarcomatous portion of the tumor by macrodissection. Representative ERMS tumor tissue was selected from 21 ERMS patient samples. Formalin-fixed paraffin-embedded tissue scrolls from each sample were analyzed using the Affymetrix Human Exon arrays. All PPB patients and 7 of 21 ERMS patients were 3 years old and younger. Twenty transcripts (10 annotated, 10 noncoding RNAs) were significantly differentially expressed in ERMS when compared with PPB samples. Insulin-like growth factor 2 (IGF2) was uniformly overexpressed in ERMS (19/21>400) but was expressed at low levels in PPB (P<0.001). Two ERMS cases that had low level IGF2 expression were 3 years and younger of age. No other differences between the 2 approached this degree of significance, despite a common rhabdomyogenic phenotype in the sarcomatous areas of PPB. PPB, unlike most ERMS, appears not to be driven by autocrine IGF2 signaling.

Pleuropulmonary blastoma in adolescence: A rare tumor beyond first decade of life

Pleuropulmonary blastoma (PPB) is a unique dysontogenetic and a primitive neoplasm occuring almost exclusively in the first decade of life, as a pulmonary- and/or pleural-based tumor with cystic, solid, or combined cystic and solid features. It is characterized histologically by a primitive, variably mixed blastematous and sarcomatous tissues. These tumors are usually associated with a poor prognosis. However, with a multimodality treatment approach, the survival of the patient can be prolonged. We herein report two cases of PPB in adolescence, a rare presentation beyond first decade of life with a short review of literature.