Type I pleuropulmonary blastoma: pathology and biology study of 51 cases from the international pleuropulmonary blastoma registry. Am J Surg Pathol. 2008;32:282-295. [PMID: 18223332 DOI: 10.1097/pas.0b013e3181484165]

A complete spectrum of congenital cystic adenomatoid malformation of the lung deceptive clinical presentations and histological surprises; a single institutional study from a tertiary care hospital in North India

Background

Congenital Cystic Adenomatoid Malformations (CCAM) are rare congenital anomalies of the lungs characterised by bronchopulmonary foregut malformations due to a sudden arrest in the development of the bronchial tree in the first trimester of the gestational period.

Aim

: The present study was aimed to describe the clinical and histopathological profiles of the patients and study patient outcomes after 1 year of surgical resection.

Methods

All patients diagnosed with CCAM by histological examination of tissue obtained on surgical resection during the study period were included in the study. Data, such as patient demographics and clinical, radiological and histopathological findings, were recorded, and follow-up information was taken on OPD follow-up till 1 year after surgery regarding respiratory infections, haemoptysis or mortality.

Results

: Out of 21 patients, 11 were female and included in the study between the ages of 1 month and 32 years, with >50% younger than 2 years. Most patients in the study had recurrent pneumonia, with difficulty in breathing being the second most common presenting complaint. All patients had undergone computed tomography (CT) of the lungs, which was able to diagnose cystic lesions accurately in >80% of cases. Histologically, all cases were classified based on recent Strocker's classification, and Type 1 was the most commonly observed with 13 cases, followed by Type 2 in five and Type 3 in three patients. There was no evidence of malignant transformation in any of the cases. There was 100% survival at the end of 1 year, with six patients having respiratory infections and none of the patients getting hospitalised over 1 year after surgery.

Conclusion

CCAM is a rare congenital anomaly associated with significant morbidity and may present at any age. It can be histologically classified into three subtypes, with Type 1 being the most common. Early surgical management is mandatory to prevent complications such as recurrent infections, respiratory distress, pneumothorax, lung abscess and malignant transformation. All patients included in the study had undergone surgical resection, and there was 100% survival at 1-year follow-up.

DICER1 Syndrome: A Multicenter Surgical Experience and Systematic Review

DICER1 syndrome is a rare genetic disorder that predisposes patients to the development of malignant and non-malignant diseases. Presently, DICER1 syndrome diagnosis still occurs late, usually following surgical operations, affecting patients' outcomes, especially for further neoplasms, which are entailed in this syndrome. For this reason, herein we present a multicenter report of DICER1 syndrome, with the prospective aim of enhancing post-surgical surveillance. A cohort of seven patients was collected among the surgical registries of Pediatric Surgery at the University of Pisa with the General and Oncologic Surgery of Federico II, University of Naples, and the Pediatric Surgery, Regina Margherita Hospital, University of Turin. In each case, the following data were analyzed: sex, age at diagnosis, age at first surgery, clinical features, familial, genetic investigations, and follow-up. A comprehensive literature review of DICER1 cases, including case reports and multicenter studies published from 1996 to June 2022, was performed. Eventually, the retrieved data from the literature were compared with the data emerging from our cohort of patients.

Genomic characterization of DICER1-associated neoplasms uncovers molecular classes

DICER1 syndrome is a tumor predisposition syndrome that is associated with up to 30 different neoplastic lesions, usually affecting children and adolescents. Here we identify a group of mesenchymal tumors which is highly associated with DICER1 syndrome, and molecularly distinct from other DICER1-associated tumors. This group of DICER1-associated mesenchymal tumors encompasses multiple well-established clinicopathological tumor entities and can be further divided into three clinically meaningful classes designated "low-grade mesenchymal tumor with DICER1 alteration" (LGMT DICER1), "sarcoma with DICER1 alteration" (SARC DICER1), and primary intracranial sarcoma with DICER1 alteration (PIS DICER1). Our study not only provides a combined approach to classify DICER1-associated neoplasms for improved clinical management but also suggests a role for global hypomethylation and other recurrent molecular events in sarcomatous differentiation in mesenchymal tumors with DICER1 alteration. Our results will facilitate future investigations into prognostication and therapeutic approaches for affected patients.

Challenges in DICER1-Associated Lung Disease

Pleuropulmonary blastoma (PPB) is a tumor occurring almost exclusively in infants and young children. This is the most common primary-lung malignancy in childhood. There is age-associated progression through a distinctive sequence of pathologic changes, from a purely multicystic lesion type I to a high-grade sarcoma type II and III. While complete resection is the cornerstone treatment for type I PPB, aggressive chemotherapy with a less favorable prognosis is associated with type II and III. DICER1 germline mutation is positive in 70% of children with PPB. Diagnosis is challenging, as it resembles congenital pulmonary airway malformation (CPAM) in imaging. Although PPB is an extremely rare malignancy, over the past five years we have encountered several children diagnosed with PPB in our medical center. Herein, we present some of these children and discuss diagnostic, ethical, and therapeutic challenges.

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.

Surgical Management of Congenital Lung Malformations

Congenital lung malformations (CLMs) are commonly diagnosed prenatal lesions with varied natural history. Prenatal diagnosis and monitoring help to guide fetal interventions, delivery planning, and need for urgent perinatal surgical interventions. All prenatally diagnosed CLMs should be evaluated postnatally, typically with cross-sectional imaging, because many lesions persist despite the appearance of complete 'regression' in utero. Management of CLMs in asymptomatic infants weighs the surgical and anesthetic risk of prophylactic resection against the risk of expectant management, including the possibility of infection, malignant degeneration, and more complicated surgical resection later with loss of compensatory lung growth.

Accuracy of Chest Computed Tomography in Distinguishing Cystic Pleuropulmonary Blastoma From Benign Congenital Lung Malformations in Children

IMPORTANCE

The ability of computed tomography (CT) to distinguish between benign congenital lung malformations and malignant cystic pleuropulmonary blastomas (PPBs) is unclear.

OBJECTIVE

To assess whether chest CT can detect malignant tumors among postnatally detected lung lesions in children.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective multicenter case-control study used a consortium database of 521 pathologically confirmed primary lung lesions from January 1, 2009, through December 31, 2015, to assess diagnostic accuracy. Preoperative CT scans of children with cystic PPB (cases) were selected and age-matched with CT scans from patients with postnatally detected congenital lung malformations (controls). Statistical analysis was performed from January 18 to September 6, 2020. Preoperative CT scans were interpreted independently by 9 experienced pediatric radiologists in a blinded fashion and analyzed from January 24, 2019, to September 6, 2020.

MAIN OUTCOMES AND MEASURES

Accuracy, sensitivity, and specificity of CT in correctly identifying children with malignant tumors.

RESULTS

Among 477 CT scans identified (282 boys [59%]; median age at CT, 3.6 months [IQR, 1.2-7.2 months]; median age at resection, 6.9 months [IQR, 4.2-12.8 months]), 40 cases were extensively reviewed; 9 cases (23%) had pathologically confirmed cystic PPB. The median age at CT was 7.3 months (IQR, 2.9-22.4 months), and median age at resection was 8.7 months (IQR, 5.0-24.4 months). The sensitivity of CT for detecting PPB was 58%, and the specificity was 83%. High suspicion for malignancy correlated with PPB pathology (odds ratio, 13.5; 95% CI, 2.7-67.3; P = .002). There was poor interrater reliability (κ = 0.36 [range, 0.06-0.64]; P < .001) and no significant difference in specific imaging characteristics between PPB and benign cystic lesions. The overall accuracy rate for distinguishing benign vs malignant lesions was 81%.

CONCLUSIONS AND RELEVANCE

This study suggests that chest CT, the current criterion standard imaging modality to assess the lung parenchyma, may not accurately and reliably distinguish PPB from benign congenital lung malformations in children. In any cystic lung lesion without a prenatal diagnosis, operative management to confirm pathologic diagnosis is warranted.

DICER1-associated hepatic cystic neoplasm with pleuropulmonary blastoma-like features: a novel clinicopathologic diagnosis

This report documents a unique multicystic neoplasm of the liver in an 8-month-old boy with a heterozygous germline pathogenic DICER1 variant. This neoplasm, initially considered most likely a mesenchymal hamartoma based on imaging, demonstrated the characteristic histologic pattern of embryonal rhabdomyosarcoma residing in the subepithelial or cambium layer-like zone of the epithelial-lined cysts. Thus, although the differential diagnosis includes mesenchymal hamartoma, a young child with a multicystic mass lesion in the liver, lung, or kidney should both raise the possibility of a germline pathogenic DICER1 variant and also not be mistaken for one of the other hepatic neoplasms of childhood.

Congenital lung lesions: a radiographic pattern approach

Congenital lung malformations represent a spectrum of abnormalities that can overlap in imaging appearance and frequently coexist in the same child. Imaging diagnosis in the neonatal period can be challenging; however, the recognition of several archetypal radiographic patterns can aid in narrowing the differential diagnosis. Major radiographic archetypes include (1) hyperlucent lung, (2) pulmonary cysts, (3) focal opacity and (4) normal radiograph. Here we review the multimodality imaging appearances of the most commonly seen congenital lung malformations, categorized by their primary imaging archetypes. Along with the congenital lung malformations, we present several important imaging mimickers.

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 (PPB) in Child with DICER1 Mutation: The First Case Report in the State of Qatar

Pleuropulmonary blastoma (PPB) is a rare intrathoracic malignancy, which arises from the lung parenchyma and/or pleura. PPB has strong genetic association with mutations in DICER1 gene. Despite being rare, PPB is the most common lung tumor in children below 6 years of age. International registry of the disease has a total of 350 cases worldwide. We report the first case of PPB in the state of Qatar, which presented as a large cystic lung lesion. The patient was first thought to have benign congenital pulmonary airway malformation (CPAM) based on chest X-ray findings. The diagnosis of PPB was suspected based on chest CT scan findings and was confirmed after surgical resection of the cystic mass. The case highlights the need to consider PPB in the differential diagnosis of cystic lung lesions in children and the need for further radiological imaging (i.e., CT scan), genetic testing, and/or excisional biopsy to confirm the diagnosis.

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

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

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

STUDY OBJECTIVE

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

RESULTS

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

CONCLUSION

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

A rare case report of simultaneous occurrence of a pediatric pleuropulmonary blastoma and an intralobar pulmonary sequestration

We are presenting a rare case with the simultaneous occurrence of pleuropulmonary blastoma and an intra lobar pulmonary sequestration. Although there have been cases reported previously with pleuropulmonary blastoma associated with congenital pulmonary malformations, the association with an intra lobar pulmonary sequestration is very rare. The patient, a female, 6-month-old child arrived at our pediatric service with the clinic of cough, respiratory distress, and fever after being treated for 2 weeks for left lung bronchopneumonia according clinical signs and radiographic description but without clinical improvements. Contrast enhanced CT images showed the simultaneous presence of 2 different lesions in the left lung, a heterogeneous mass in the superior lobe without delineation with mediastinal structure compatible with a pleuropulmonary blastoma and a consolidation in the inferior lobe with bronchogram present and a systemic vessel feeding compatible with an intra lobar pulmonary sequestration, both confirmed by histologic examinations after the surgical intervention. Although it is very rare, the simultaneous presence of these distinct embryogenic lesions may occur and radiologist should be aware as the imaging diagnosis may be very helpful for the further management of the patient.

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.

Pleuropulmonary Blastoma in Pediatric Lung Lesions

BACKGROUND

Pediatric lung lesions are a group of mostly benign pulmonary anomalies with a broad spectrum of clinical disease and histopathology. Our objective was to evaluate the characteristics of children undergoing resection of a primary lung lesion and to identify preoperative risk factors for malignancy.

METHODS

A retrospective cohort study was conducted by using an operative database of 521 primary lung lesions managed at 11 children's hospitals in the United States. Multivariable logistic regression was used to examine the relationship between preoperative characteristics and risk of malignancy, including pleuropulmonary blastoma (PPB).

RESULTS

None of the 344 prenatally diagnosed lesions had malignant pathology (P < .0001). Among 177 children without a history of prenatal detection, 15 (8.7%) were classified as having a malignant tumor (type 1 PPB, n = 11; other PPB, n = 3; adenocarcinoma, n = 1) at a median age of 20.7 months (interquartile range, 7.9-58.1). Malignancy was associated with the DICER1 mutation in 8 (57%) PPB cases. No malignant lesion had a systemic feeding vessel (P = .0427). The sensitivity of preoperative chest computed tomography (CT) for detecting malignant pathology was 33.3% (95% confidence interval [CI]: 15.2-58.3). Multivariable logistic regression revealed that increased suspicion of malignancy by CT and bilateral disease were significant predictors of malignant pathology (odds ratios of 42.15 [95% CI, 7.43-340.3; P < .0001] and 42.03 [95% CI, 3.51-995.6; P = .0041], respectively).

CONCLUSIONS

In pediatric lung masses initially diagnosed after birth, the risk of PPB approached 10%. These results strongly caution against routine nonoperative management in this patient population. DICER1 testing may be helpful given the poor sensitivity of CT for identifying malignant pathology.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Type II Pleuropulmonary Blastoma in a 4 Month Old Infant with Negative Dicer1 Mutation on Next Generation Sequencing

INTRODUCTION

Pleuropulmonary blastoma (PPB) is a rare, but aggressive tumor in the pediatric population. PPB is a dysontogenetic neoplasm of childhood that involves the lungs and/or pleura. Young relatives of children with PPB have an increased incidence of neoplasias and dysplasias. According to tumor tissue histopathology, PPB evolves from a cystic to solid state over time. PPBs can be sub-classified as type I (purely cystic), type II (having both cystic and solid elements), and type III (completely solid). Type II and type III tumors may be associated with metastasis, with the brain being the most common metastatic site. Due to the primitive nature of cells in the tumor mass, PPBs are very aggressive tumors that are resistant to therapy. The prognosis depends on the histopathology content and tumor type. Respiratory problems are the main complaint and diagnosis can be made only after additional examinations. Genetic relations through family members are associated with mutations in the DICER1 gene; between 60-80% of patients with PPBs are positive for DICER1 mutations. Mosaicism has also been reported.

AIM

The aim was to present a case of a 4 month-old infant with type II PPB, who had a negative result for DICER1 mutation in next generation sequencing. To detail the clinical presentation of this patient, we present radiographic and ultrasound findings and results of histopathological analysis, as well as genetic and scintigraphic findings and chemotherapy treatment.

CASE REPORT

Here we describe the genetic analysis of a patient with PPB who was negative for mutations in DICER1 and who had no relatives with disease. This patient underwent radical resection of the tumor and began therapy, but subsequently died after developing leukopenia and sepsis.

CONCLUSION

This case provides an example of a patient with PPB who was negative for DICER1 mutation upon genetic analysis and emphasizes the potential for disease that does not involve mutation of this gene.

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.

Deletion of Yy1 in mouse lung epithelium unveils molecular mechanisms governing pleuropulmonary blastoma pathogenesis

Pleuropulmonary blastoma (PPB) is a very rare pediatric lung disease. It can progress from abnormal epithelial cysts to an aggressive sarcoma with poor survival. PPB is difficult to diagnose as it can be confounded with other cystic lung disorders, such as congenital pulmonary airway malformation (CPAM). PPB is associated with mutations in DICER1 that perturb the microRNA (miRNA) profile in lung. How DICER1 and miRNAs act during PPB pathogenesis remains unsolved. Lung epithelial deletion of the Yin Yang1 (Yy1) gene in mice causes a phenotype mimicking the cystic form of PPB and affects the expression of key regulators of lung development. Similar changes in expression were observed in PPB but not in CPAM lung biopsies, revealing a distinctive PPB molecular signature. Deregulation of molecules promoting epithelial-mesenchymal transition (EMT) was detected in PPB specimens, suggesting that EMT might participate in tumor progression. Changes in miRNA expression also occurred in PPB lung biopsies. miR-125a-3p, a candidate to regulate YY1 expression and lung branching, was abnormally highly expressed in PPB samples. Together, these findings support the concept that reduced expression of YY1, due to the abnormal miRNA profile resulting from DICER1 mutations, contributes to PPB development via its impact on the expression of key lung developmental genes.This article has an associated First Person interview with the joint first authors of the paper.

Pediatric Cystic Lung Lesions: Where Are We Now?

Pediatric cystic lung lesions have long been a source of confusion for clinicians, radiologists, and pathologists. They encompass a wide spectrum of entities with variable prognostic implications, including congenital lung malformations, pulmonary neoplasms, and hereditary conditions. As our understanding of the developmental and genetic origins of these conditions has evolved, revised nomenclature and classifications have emerged in an attempt to bring clarity to the origin of these lesions and guide clinical management. This review discusses cystic lung lesions and the current understanding of their etiopathogenesis.

Exceptional response to radiotherapy in unresectable pleuropulmonary blastoma of a child

Pleuropulmonary blastoma (PPB) is a rare intrathoracic neoplasm in children. Although surgery with or without chemotherapy mainly conducted, the response of radiotherapy (RT) has not been evaluated yet. For unresectable tumor, RT might be considered as one option to decrease tumor extent to relieve obstructing symptoms or to facilitate successive treatment. We report one child in whom PPB with DICER1 mutation recurred after surgery and lead to respiratory distress. She emergently received palliative RT with a relatively low dose (20 Gy), and symptoms sufficiently relieved. Even she showed an 84.3% reduction in diameter and maintained the remission status for 1 year. These might reflect possible radiosensitivity of PPB, and further investigations of RT might be necessary for unresectable PPB.

Early KRAS oncogenic driver mutations in nonmucinous tissue of congenital pulmonary airway malformations as an indicator of potential malignant behavior

The potential for malignant degeneration is the most common reason for some practitioners to resect asymptomatic congenital pulmonary airway malformations (CPAMs). We aimed to investigate the potential of various immunohistochemical (IHC) and genomic biomarkers to predict the presence of mucinous proliferations (MPs) in CPAM. Archival CPAM tissue samples were re-assessed and underwent IHC analysis using a panel of differentiating markers (TTF1/CDX2/CC10/MUC2/MUC5AC/p16/p53/DICER1). In each sample, intensity of IHC staining was assessed separately in normal lung tissue, CPAM, and MP tissue, using a semiquantitative approach. Likewise, next-generation targeted sequencing of known adult lung driver mutations, including KRAS/BRAF/EGFR/ERBB2, was performed in all samples with MP and in control samples of CPAM tissue without MP. We analyzed samples of 25 CPAM type 1 and 25 CPAM type 2 and found MPs in 11 samples. They were all characterized by strong MUC5AC expression, and all carried a KRAS mutation in the MP and adjacent nonmucinous CPAM tissue, whereas the surrounding normal lung tissue was negative. By contrast, in less than half (5 out of 12) control samples lacking MP, the CPAM tissue also carried a KRAS mutation. KRAS mutations in nonmucinous CPAM tissue may identify lesions with a potential for malignant degeneration and may guide histopathological assessment and patient follow-up.

DICER1 Hotspot Mutations in Pleuropulmonary Blastoma: A Case Series From a Tertiary Center

Pleuropulmonary blastoma (PPB) is a potentially aggressive, rare childhood neoplasia. We investigated histopathological features, survival, and DICER1 hotspot mutations among PPB patients. Archive records at our institution were reviewed, covering a 20-year period. Thirteen children (6 males and 7 females) with a mean age of 30.5 (range 6-83) months were included. The tumor subtypes were type I in 6 (46%), type II in 4 (31%), and type III in 3 (23%). Only tumors with type II and type III histology showed anaplasia (4/7, 57%). Median follow-up was 28 (range 9-216) months. Three-year overall survival rate was 83.3% and 3-year progression-free survival rate was 25%. Progression was seen in 60% (3/5) of type I and 66.7% (4/6) of type II and type III cases. Two patients died of disseminated disease at 9 and 44 months. Hotspot missense mutations on DICER1 gene were detected in all 11 patients with available tumor tissue. We found an additional novel germline loss-of-function mutation (c.5436dupT; p.E1813*) in 1 case. To the best of our knowledge, this is the first study to investigate hotspot missense mutations on DICER1 gene among the largest series of Turkish children with PPB.

Pleuropulmonary blastoma type I might arise in congenital pulmonary airway malformation type 4 by acquiring a Dicer 1 mutation

Congenital pulmonary airway malformation (CPAM) occurs most commonly in infants. It is divided into 5 types. The most common types 1 and 2 are cystic, type 0 presents as bronchial buds without alveolar tissue, most likely corresponding to alveolar dysgenesis, while type 3 is composed of branching bronchioles and appears as a solid lesion. A defect in the epithelial-mesenchymal crosstalk might be the underlying mechanism for all. Type 4 is a peripheral cystic lesion with a thin cyst wall covered by pneumocytes. CPAM 4 has been mixed up with pleuropulmonary blastoma (PPB) type I and some authors question its existence. We investigated five cases of CPAM type 4 for the presence or absence of rhabdomyoblasts, and for markers associated with CPAM development. In addition, all cases were evaluated for mutations within the Dicer gene and for mutations of the RAS family of oncogenes. All five cases showed smooth muscle actin and desmin-positive cells; however, only one case showed a few cells positive for MyoD. The same case showed a mutation of Dicer 1. All cases were negative for mutations of the RAS family of genes. Fibroblast growth factor 10 was similarly expressed in all cases, and thus cannot be used to differentiate CPAM4 from PPB-I. Low expression of the proliferation marker Ki67 was seen in our CPAM 4 cases and the probable PPB-I case. YingYang-1 protein seems to play an active role in the development of PPB-I. CPAM 4 can be separated from PPB-I based on the presence of rhabdomyoblasts and mutations in Dicer 1 gene. These cells might not be numerous; therefore, all available tissue has to be evaluated. As CPAM 4 morphologically looks very similar to PPB-I, it might be speculated, that there exists a potential for progression from CPAM 4 to PPB-I, by acquiring somatic mutations in Dicer 1.

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.

Hotspot Mutations in DICER1 Causing GLOW Syndrome-Associated Macrocephaly via Modulation of Specific microRNA Populations Result in the Activation of PI3K/ATK/mTOR Signaling

BACKGROUND

We have previously described mosaic mutations in the RNase IIIb domain of DICER1that display global developmental delays, lung cysts, somatic overgrowth, macrocephaly and Wilms tumor. This constellation of phenotypes was classified as GLOW syndrome. Due to the phenotypic overlap between GLOW and syndromes caused by mutations in the PI3K/AKT/mTOR pathway, we hypothesized that alterations in miRNA regulation of this pathway cause its specific constellation of phenotypes.

OBJECTIVE

To test the hypothesis that DICER1 "hot spot" mutations associated with GLOW syndrome activate PI3K/AKT/mTOR signaling.

METHODS

We developed HEK293T cells with loss of exon 25 in DICER1, a genetic modification that is synonymous with the "hot spot" RNAseIIIb mutations that cause GLOW syndrome. We assayed the cells for activation of the PI3K/AKT/mTOR signaling pathway.

RESULTS

We observed activation of the PI3K/AKT/mTOR pathway as demonstrated by increased pS6Kinase, p4EBP1 and pTSC2 levels. Additionally, these cells demonstrate a striking cellular phenotype, with the ability to form spheres when the serum is removed from their growth medium. The cells in these spheres are Oct4 and Sox2 positive and exhibit the property of reversion with the addition of serum. We queried miRNA expression data and identified a population of miRNAs that increase due to these mutations and target negative regulators of the PI3K/AKT/mTOR pathway.

CONCLUSION

This work identifies the delicate and essential role for miRNA control of the PI3K/AKT/mTOR pathway. We conclude that the phenotypes observed in the GLOW syndrome are the result of PI3K/AKT/mTOR activation.

Type I pleuropulmonary blastoma presenting as congenital pulmonary airway malformation: A report of two cases

Pleuropulmonary blastoma (PPB) is a rare aggressive intrathoracic tumor which is believed to originate from embryonic uncommitted lung mesenchymal cells, which are important for developing the lung. Type I PPB is cystic, type II is cystic and solid, while type III is predominantly solid. Diagnosing type 1 PPB is a challenge for both radiologists as well as pathologists. Owing to its purely cystic nature, type I PPB it is often mistaken for unrelated entities such as congenital pulmonary airway malformation and congenital lobar emphysema which delays surgical intervention. Here, we report two such cases presenting clinically and radiologically as congenital pulmonary airway malformation. On histology, a final diagnosis of type I pleuropulmonay blastoma was made. Thereafter, chemotherapy was administered following complete surgical excision.

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.

Primary Lung Tumors in Children: Radiologic-Pathologic Correlation From the Radiologic Pathology Archives

Primary lung tumors in children are rare, with a narrow range of diagnostic considerations. However, the overlapping imaging appearances of these tumors necessitate attention to key discriminating imaging and pathologic features. In the neonate and infant, the important considerations include pleuropulmonary blastoma (PPB), infantile fibrosarcoma, and fetal lung interstitial tumor. Among these tumors, imaging findings such as air-filled cysts in type 1 PPB and homogeneously low attenuation of fetal lung interstitial tumors are relatively specific. Key pathologic and genetic discriminators among this group of tumors include the DICER1 germline mutation found in PPB and the t(12,15)(p13;q25) translocation and ETV6-NTRK3 fusion gene seen in infantile fibrosarcoma. Primary lung tumors in older children include inflammatory myofibroblastic tumors (IMTs), carcinoid salivary gland-type tumors of the lung, recurrent respiratory papillomatosis, and other rare entities. IMT, a spindle-cell proliferation with inflammatory elements, is the most common lung tumor in children. Anaplastic lymphoma kinase, a receptor-type protein tyrosine kinase, is present in 50% of these tumors, and this finding may support an imaging diagnosis of IMT. Carcinoid tumors account for a substantial portion of childhood lung tumors, and their characteristic avid enhancement on images corresponds to the compressed fibrovascular stroma histologically. Furthermore, novel imaging agents used with somatostatin receptor analogs have an emerging role in the evaluation of carcinoid tumors. Although less common than mucoepidermoid carcinoma, adenoid cystic carcinoma tends to recur given the perineural spread seen histologically. Integrating radiologic and pathologic knowledge is critical to accurate diagnosis, treatment planning, and surveillance of primary lung tumors in children.

Pleuropulmonary blastoma: a report from the TREP (Tumori Rari in Età Pediatrica) Project

INTRODUCTION

Pleuropulmonary blastoma (PPB) is a rare, aggressive mesenchymal tumor of childhood. The Italian Tumori Rari in Età Pediatrica (TREP) Registry was the first in Europe dedicated to prospective data collection on rare pediatric tumors. We analyzed data from an Italian series of patients with PPB, focusing on the role of the TREP Project.

METHODS

We considered patients aged 0-14 with histologically confirmed diagnosis, registered in population-based cancer registries (before 2000) or the TREP Registry (2000 to 2014), and analyzed data on clinical characteristics, treatment, and outcome. Event-free survival (EFS) and overall survival (OS) were estimated. Relevant prognostic factors were identified performing a univariate analysis.

RESULTS

Thirty-seven cases were included (7 type I, 13 type II, 17 type III). The average diagnosis rate rose from 1.10 to 1.73 cases/year after the TREP Project started. All patients underwent surgery, 33 received chemotherapy, and 9 had radiotherapy. The median follow-up was 8.7 years. For type I, II, and III, respectively, the 5-year OS was 85.7% (33.4-97.9), 52.7% (23.4-75.5), and 57.8% (31.1-77.3); the 5-year EFS was 85.7% (33.4-97.9), 52.7% (23.4-75.5), and 52.9% (27.6-73.0). Favorable prognostic factors for EFS were Intergroup Rhabdomyosarcoma Study (IRS) stage I (p = 0.03) and T1 tumor (p = 0.05). A total of 78.3% of patients who had chemotherapy after 2000 received a standardized treatment.

CONCLUSIONS

The TREP Registry showed an excellent capacity for registering cases of PPB. Patients received homogeneous treatment after the TREP Project started. Long-term outcomes were excellent for type I and unsatisfactory for type II and III. Tumor invasiveness and IRS stage were of prognostic value.

NCAM1/FGF module serves as a putative pleuropulmonary blastoma therapeutic target

Pleuropulmonary blastoma (PPB) is a rare pediatric lung neoplasm that recapitulates developmental pathways of early embryonic lungs. As lung development proceeds with highly regulated mesenchymal-epithelial interactions, a DICER1 mutation in PPB generates a faulty lung differentiation program with resultant biphasic tumors composed of a primitive epithelial and mesenchymal stroma with early progenitor blastomatous cells. Deciphering of PPB progression has been hampered by the difficulty of culturing PPB cells, and specifically progenitor blastomatous cells. Here, we show that in contrast with in-vitro culture, establishment of PPB patient-derived xenograft (PDX) in NOD-SCID mice selects for highly proliferating progenitor blastoma overexpressing critical regulators of lung development and multiple imprinted genes. These stem-like tumors were sequentially interrogated by gene profiling to show a FGF module that is activated alongside Neural cell adhesion molecule 1 (NCAM1). Targeting the progenitor blastoma and these transitions with an anti-NCAM1 immunoconjugate (Lorvotuzumab mertansine) inhibited tumor growth and progression providing new paradigms for PPB therapeutics. Altogether, our novel in-vivo PPB xenograft model allowed us to enrich for highly proliferating stem-like cells and to identify FGFR and NCAM1 as two key players that can serve as therapeutic targets in this poorly understood and aggressive disease.

The Diagnosis of Pleural Tumors Other Than Mesothelioma

CONTEXT

- Pleural pathology has been dominated by discussions relating to the diagnosis, prognosis, etiology, and management of malignant mesothelioma. However, there exists a diverse group of other neoplasms that involve the pleura; the most common by far is metastatic carcinoma, usually of pulmonary origin. Other metastatic tumors of varied histogenesis do occur but are less common. Primary pleural neoplasms other than diffuse malignant mesothelioma are either uncommon or rare and have received less attention.

OBJECTIVE

- To provide a review of those diverse tumors that can involve the pleura other than mesothelioma in order to facilitate their accurate diagnosis.

DATA SOURCES

- Review of relevant literature published via PubMed and other search engines.

CONCLUSIONS

- A wide variety of tumors can involve the pleura. In most cases, the approach of considering the morphologic features with appropriate immunohistochemistry, in the correct clinical context, allows for a confident diagnosis. For a number of those soft tissue tumors that are well recognized in the pleura, such as solitary fibrous tumor, desmoid-type fibromatosis, synovial sarcoma, and epithelioid hemangioendothelioma, novel markers now exist based on an understanding of the individual tumors' molecular characteristics. Primary pleural lymphomas are rare with poor prognosis. They represent localized specific diffuse large B-cell lymphomas, with either post-germinal center B-cell or plasma cell lineage, arising in the context of either immunodeficiency or immune sequestration and with viral infection.

Type I regressed pleuropulmonary blastoma in a 10-year-old boy

Pleuropulmonary blastoma (PPB) is a rare, malignant tumor of the lung and is the most common primary pulmonary malignancy in children. Here, we report a case of a boy who was diagnosed with type I regressed PPB after being mislabeled with congenital pulmonary malformation. A 10-year-old boy presented to our hospital with a history of worsening dyspnea. Since birth, his clinical status and radiographic images were concerning for congenital lobar emphysema that was managed conservatively. A chest computed tomography (CT) scan confirmed the persistence of a large cystic lesion and a diagnostic and therapeutic cystectomy was performed. Microscopic examination confirmed the presence of PPB type Ir. Patient was managed surgically alone with no added chemotherapy, as there was no overall survival benefit. PPB Ir has an overall favorable clinical outcome. Limited follow-up data are available due to the rarity of the lesion and the overlap with other congenital cystic lung malformations.

Novel intronic DICER1 variation associated with pleuropulmonary blastoma in two siblings

Pleuropulmonary blastomas (PPB) are rare aggressive paediatric lung malignancies associated with DICER1 variants. We present two cases, a 2-year-old girl with upper respiratory tract symptoms as well as a 6-month-old girl sibling undergoing screening due to family history of malignancy. Imaging of the 2-year-old girl revealed a large mass filling the right hemithorax which was determined to be a type II PPB after pathological examination. Imaging of the 6-month-old sibling demonstrated a small cystic lesion in the posterior basal segment of the right lower lobe which was determined to be a type 1r PPB after pathological examination. The 2-year-old girl received adjuvant chemotherapy while the baby sister underwent resection alone and both are alive and well at 12 months and 7 months, respectively. Sequence analysis in both cases confirmed the same DICER1 variation, c.2437-2A>G (likely pathogenic), which has not been previously described in the literature.

Pleuropulmonary Blastoma Developing in a Case of Misinterpreted Congenital Pulmonary Airway Malformation: a Case Report

BACKGROUND

Pleuropulmonary blastoma (PPB) is a childhood malignancy known to be associated with congenital pulmonary airway malformation (CPAM).

CASE REPORT

An 18 months boy presented with respiratory distress. Computed tomography (CT) scans revealed a large right-sided lung mass. Fine needle aspiration cytology (FNAC) showed sheets and clusters of small round to oval cells with scanty cytoplasm. The possibility of PPB was suggested. Trucut biopsy from the mass confirmed the diagnosis of PPB, of at least type II. The child had earlier been diagnosed as CPAM for which he had undergone lobectomy at six months, which on review was diagnosed as PPB I.

CONCLUSION

We describe the cytological and histological findings of a case of PPBII/III evolving from a PPB I originally thought to be a CPAM type IV. This supports the theory that PPB I may progress to a more aggressive type II with time, and highlights the importance of the adequately treating the PPB I to prevent this transformation.

Wilms tumor, pleuropulmonary blastoma, and DICER1: case report and literature review

Background

Pleuroblastoma (PPB) is a rare pediatric tumor which, in 30% of cases, is associated with cystic nephroma. It has been recently linked to the DICER1 mutation as part of a predisposition syndrome for various tumors. However, if DICER 1 anomalies have been reported in patients with Wilms tumor (WT), to date, no cases of PPB, WT, and DICER1 mutations have been reported in the same patient.

Case presentation

We report the case of a 3-year-old patient, initially managed for metastatic WT. During his clinical course, the diagnosis of a PPB was made after detecting the DICER1 mutation and subsequent management was therefore modified.

Conclusion

This case highlights that in case of simultaneous discovery of a renal tumor and a pulmonary lesion in a child, the DICER 1 mutations should be looked for as these could help adapt management and schedule the surgical procedures.

[Pneumoblastoma in adults: a new case report and literature review]

Le blastome pulmonaire décrit surtout chez les enfants, est une tumeur rare. Elle représente 0.25 à 0.5% de toutes les tumeurs pulmonaires avec un pronostic très grave. Sur le plan histologique, il s'agit d'une tumeur à double composante: une composante épithéliale et une composante mésenchymateuse. Cliniquement, il s'annonce souvent par des douleurs thoraciques, de la toux, des hémoptysies et de la dyspnée, mais reste asymptomatique dans environ 40% des cas. Nous rapprtons le cas d'une femme de 25 ans, sans antécédents particuliers, qui se plaignait de dyspnée, de toux et de douleurs basithoraciques gauches. l'exploration radiologique avait montré une large masse basithoracique du poumon gauche. La biopsie a été réalisée et avait ramené uniquement du matériel nécrotique. La pièce de résection était largement nécrosée, le tissu viable examiné au miroscope avait révélé un pattern biphasique, composée de tissu épithélial malin, associé à un tissu mésenchymateux malin, caractéristiques du pneumoblastome biphasique. La patiente a bénéficié d'une chimiothérapie puis radiothérapie. Le contrôle a montré une récidive et la patiente a été mise sous deuxième ligne de chimiothérapie.

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 syndrome: Approach to testing and management at a large pediatric tertiary care center

BACKGROUND

To expand the current knowledge of DICER1 syndrome and to propose criteria for genetic testing based on experience at a pediatric tertiary care center.

PROCEDURE

This study involved a retrospective chart review of the 78 patients (47 probands and 31 family members) seen in the Cancer Genetics Program at The Hospital for Sick Children (SickKids) who were offered genetic testing for DICER1.

RESULTS

Of 47 probands offered genetic testing for DICER1, 46 pursued testing: 11 (23.9%) carried a pathogenic variant and one proband (2.1%) carried a missense variant of uncertain significance with evidence for pathogenicity. Thirty-one family members of variant-positive probands were offered testing: eight of the 25 who agreed to testing carried their familial variant (32.0%). Overall, 20 patients were identified to have a variant in DICER1 (eight males, 12 females). Of these, 13 (65.0%) presented with clinical manifestations associated with the syndrome. The most common lesions were pleuropulmonary blastoma (PPB) (five of 20 patients, 25.0%) and pineoblastoma (three of 20 patients, 15.0%). The average age at which individuals were diagnosed with a primary neoplasm was 5.2 years (range 0.8-20 years, median 3.0). Surveillance at our institution, with a median follow-up time of 23 months, has identified PPB in two asymptomatic individuals. These lesions were identified at early stages, thus potentially reducing treatment-related morbidity and mortality.

CONCLUSION

This study further delineates the DICER1 syndrome phenotype and demonstrates the feasibility of a DICER1 syndrome surveillance protocol for the early detection of tumors.

Neonatal congenital lung tumors - the importance of mid-second-trimester ultrasound as a diagnostic clue

BACKGROUND

The differential diagnosis for primary lung masses in neonates includes a variety of developmental abnormalities; it also consists of the much rarer congenital primary lung tumors: cystic pleuropulmonary blastoma (cystic PPB), fetal lung interstitial tumor (FLIT), congenital peribronchial myofibroblastic tumor (CPMT), and congenital fibrosarcoma. Radiologic differentiation between malformations and tumors is often very challenging.

OBJECTIVE

The objective was to establish distinctive features between developmental pulmonary abnormalities and primary lung tumors.

MATERIALS AND METHODS

We conducted a retrospective study of 135 congenital lung lesions at a university mother and child center over a period of 10 years (2005-2015). During this time, we noted four tumors (two cystic PPBs and two FLITs) and 131 malformations. We recorded the following parameters: timing of conspicuity in utero (mid-second trimester, third trimester, or not seen prenatally), presence of symptoms at birth, prenatal and perinatal radiologic findings, and either histological diagnoses by pathology or follow-up imaging in non-operated cases.

RESULTS

All lesions except the four tumors were detected during mid-second-trimester ultrasound. In none of the tumors was any pulmonary abnormality found on the mid-second-trimester sonogram, contrary to the developmental pulmonary abnormalities.

CONCLUSION

The timing of conspicuity in utero appears to be a key feature for the differentiation between malformations and tumors. Lesions that were not visible at the mid-second-trimester ultrasound should be considered as tumor. A cystic lung lesion in the context of a normal mid-second-trimester ultrasound is highly suggestive of a cystic PPB. Differentiating the types of solid congenital lung tumors based upon imaging features is not yet feasible.

Long-term outcomes of congenital lung malformations

Congenital lung malformations comprise a group of anatomical abnormalities of the respiratory tree including congenital cystic malformations, bronchopulmonary sequestrations, bronchogenic cyst, bronchial atresia, and congenital lobar emphysema. These anomalies are detected with increasing frequency by pre-natal sonography, but may also present for the first time with symptoms in childhood or later life. When symptomatic, there is little controversy that resection is indicated, which is usually curative. When a lesion is asymptomatic there is greater debate regarding the benefit of resection versus continued observation. This article provides an overview of the spectrum of disorders, the management options available and the long-term outcomes associated with each treatment option.

Type III pleuropulmonary blastoma in a dicer1 germline mutation carrier: The management of residual lung cystic lesions

Pleuropulmonary blastoma (PPB) is a rare malignancy of childhood. It often represents a manifestation of a hereditary tumor predisposition syndrome (DICER1 syndrome). Because of its malignant potential, surgical resection of cystic lung lesions is recommended in germline DICER1 mutation carriers. We present a case of a 3-year-old male child with type III PPB successfully managed with ifosfamide, vincristine, actinomycin-D, and doxorubicin (IVADo) chemotherapy and surgery. A heterozygous germline pR688X mutation of DICER1 gene was demonstrated. Six years after primary diagnosis, several small lung cysts remained stable without further therapy. The management of residual asymptomatic lung cysts represents a clinical challenge in these patients.