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]

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.

Congenital Cystic Adenomatoid Malformation: A Tertiary Care Hospital Experience

INTRODUCTION

Congenital Cystic Adenomatoid Malformation (CCAM) is an uncommon developmental deformity affecting the terminal respiratory structures. It is characterized by broncho pulmonary foregut malformations. The reason behind it is an arrest in lung development between 4^th and 7^th week of fetal life.

AIM

The present study was conducted to assess the clinical and radiological profile and also to study the role of surgical intervention in patients with CCAM.

MATERIALS AND METHODS

All patients with clinical suspicion or provisional diagnosis of CCAM were included in the study. A clinical questionnaire was prepared to collect data. Computed Tomography (CT) chest with High Resolution Computed Tomography (HRCT) was done for all the patients. Patients were assessed by paediatric surgeon and eligible patients were operated. The procedure conducted was usually open thoracotomy under general anaesthesia. The affected lobes were removed and specimens were sent for histopathological analysis. All included patients were followed up prospectively to find out about their current level of health. Via telephonic interview they were asked about their overall growth, quality of life, activity, rate of respiratory infections and requirement of hospital admission.

RESULTS

Total 15 patients with diagnosis of CCAM were included in the study. Of them, 8 (53.3%) were male. The commonest presentation was cough 13(86%), breathing difficulty 11(73%), fever 9(60%), recurrent pneumonia 4(26%), hypoxia requiring oxygen supplementation 6(40%), others 2(12%). Thirteen patients required surgical intervention and underwent lobectomy. There were 2 cases of type I, one each of type II and III, 3 case of type IV while 5 were intermediate type. There was no procedure related mortality. The median duration of hospital stay and all were successfully discharged with median duration of stay 11±16 days.

CONCLUSION

The study concludes that if recognized early, surgical removal of affected lung prevents the complications like recurrent pulmonary infections. The surgery is well tolerated without any post-operative mortality or morbidity.

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.

Association between Congenital Lung Malformations and Lung Tumors in Children and Adults: A Systematic Review

INTRODUCTION

The appropriate management of asymptomatic congenital pulmonary malformations (CPMs) remains controversial. Prophylactic surgery is recommended to avoid the risk for development of pulmonary infections and to prevent the highly debated development of malignancy. However, the true risk for development of malignancy remains unknown. A systematic review analyzed all cases in which lung tumors associated with CPMs in both the pediatric and adult populations were described.

METHODS

A comprehensive literature search was carried out; it included all the cases in which an association between CPMs and malignant pulmonary lesions was reported.

RESULTS

In all, 134 publications were eligible for inclusion. In 168 patients CPM was found associated with lung tumor. The diagnosis was made in 76 children at a mean age of 3.68 ± 3.4, whereas in the adult population (n = 92) it was made at a mean age of 44.62 ± 16.09. Cough was the most frequent presenting symptom both in children and in adults. Most of the patients underwent lobectomy. The tumor most often associated with CPM was pleuropulmonary bastoma in children (n = 31) and adenocarcinoma (n = 20) or bronchioloalveolar carcinoma (n = 20) in adults. The CPM most frequenty associated with tumors in children was congenital cystic adenomatoid malformation (n = 37), especially type 1 (n = 21), whereas in adults it was bronchogenic cyst (n = 25), followed by congenital cystic adenomatoid malformation (n = 21).

CONCLUSIONS

CPMs should be followed up and never underestimated because they may conceal a tumor. Apparently, there is no age limit for malignant progression of CPMs and no limit of the interval between first detection of the CPM and appearance of the associated tumor.

Pathology of asymptomatic, prenatally diagnosed cystic lung malformations

AIM

The management of asymptomatic congenital cystic lung malformations is controversial. Arguments for excision of asymptomatic lesions are the potential for infection and malignancy. Following antenatal detection, our institute performs a CT at 1month, clinic follow-up by 3months to discuss the controversial management, and offers surgery by 6months of age. We investigated the histopathology of asymptomatic lesions to determine whether there was evidence of subclinical infection or malignancy.

METHODS

A retrospective review of prospectively collected antenatal congenital cystic lung malformations more than a 10year period (2005-2014) was conducted. Information was gathered from the antenatal registry and histopathology reports. Infection was defined by the presence of microabscesses or neutrophil/macrophage infiltration, as per histopathological criteria.

MAIN RESULTS

From the cohort of 99 patients, the study focused on 69 asymptomatic lesions. These cases comprised 34 congenital pulmonary airway malformations (CPAM), 15 pulmonary sequestrations (PS), and 20 hybrid lesions. Eighteen cases (26%) had microscopic disease - 16 cases of infection and 2 tumors. The infectious cases comprised 7 with microabscesses and 9 with neutrophil/macrophage infiltration. There were two cases of tumors, namely pleuropulmonary blastoma. These tumors were followed up by the oncology team with regular imaging until 3years of age and clinical review thereafter.

CONCLUSION

Twenty-six percent of antenatally detected, asymptomatic cystic lung malformations demonstrated either subclinical infection or malignancy. This information can be used for counseling parents and determining the method of treatment.

Can congenital pulmonary airway malformation be distinguished from Type I pleuropulmonary blastoma based on clinical and radiological features?

BACKGROUND

The management of congenital cystic lung lesions is controversial. Arguments for routine resection during infancy include the possibility of the lesion being Type I pleuropulmonary blastoma (PPB) rather than a cystic congenital pulmonary airway malformation (CPAM). We aimed to identify clinical and radiological features that might distinguish between CPAM and PPB and to develop a diagnostic algorithm based on these features.

METHODS

All recorded cases of Type I PPB were retrieved from the International PPB Registry and compared with an institutional cohort of children undergoing resection of CPAM (2002-2013) that was noted at some stage to be at least partially cystic. Regression models were created to identify variables that might differentiate CPAM from PPB. Odds ratio (OR) and positive predictive value (PPV) were calculated for each variable and a decision algorithm developed.

RESULTS

In 112 cases of Type I PPB and 103 of CPAM, factors favoring a diagnosis of CPAM included prenatal detection (OR 89.4), systemic feeding vessel (OR 61.7), asymptomatic (OR 8.0), and hyperinflated lung (OR 6.6). Factors favoring a diagnosis of PPB included bilateral or multisegment involvement (OR 2.4). A decision algorithm that helps to identify lesions requiring resection and those which can be safely observed is presented.

CONCLUSION

Clinical and radiological features can help to differentiate between CPAM and PPB. Our algorithm allows identification of children at higher risk of PPB in whom we would recommend resection and those at low risk in whom continued close observation is safe.

Epithelial inactivation of Yy1 abrogates lung branching morphogenesis

Yin Yang 1 (YY1) is a multifunctional zinc-finger-containing transcription factor that plays crucial roles in numerous biological processes by selectively activating or repressing transcription, depending upon promoter contextual differences and specific protein interactions. In mice, Yy1 null mutants die early in gestation whereas Yy1 hypomorphs die at birth from lung defects. We studied how the epithelial-specific inactivation of Yy1 impacts on lung development. The Yy1 mutation in lung epithelium resulted in neonatal death due to respiratory failure. It impaired tracheal cartilage formation, altered cell differentiation, abrogated lung branching and caused airway dilation similar to that seen in human congenital cystic lung diseases. The cystic lung phenotype in Yy1 mutants can be partly explained by the reduced expression of Shh, a transcriptional target of YY1, in lung endoderm, and the subsequent derepression of mesenchymal Fgf10 expression. Accordingly, SHH supplementation partially rescued the lung phenotype in vitro. Analysis of human lung tissues revealed decreased YY1 expression in children with pleuropulmonary blastoma (PPB), a rare pediatric lung tumor arising during fetal development and associated with DICER1 mutations. No evidence for a potential genetic interplay between murine Dicer and Yy1 genes during lung morphogenesis was observed. However, the cystic lung phenotype resulting from the epithelial inactivation of Dicer function mimics the Yy1 lung malformations with similar changes in Shh and Fgf10 expression. Together, our data demonstrate the crucial requirement for YY1 in lung morphogenesis and identify Yy1 mutant mice as a potential model for studying the genetic basis of PPB.

Diffuse Cystic Lung Disease. Part I

The diffuse cystic lung diseases (DCLDs) are a group of pathophysiologically heterogenous processes that are characterized by the presence of multiple spherical or irregularly shaped, thin-walled, air-filled spaces within the pulmonary parenchyma. Although the mechanisms of cyst formation remain incompletely defined for all DCLDs, in most cases lung remodeling associated with inflammatory or infiltrative processes results in displacement, destruction, or replacement of alveolar septa, distal airways, and small vessels within the secondary lobules of the lung. The DCLDs can be broadly classified according to underlying etiology as those caused by low-grade or high-grade metastasizing neoplasms, polyclonal or monoclonal lymphoproliferative disorders, infections, interstitial lung diseases, smoking, and congenital or developmental defects. In the first of a two-part series, we present an overview of the cystic lung diseases caused by neoplasms, infections, smoking-related diseases, and interstitial lung diseases, with a focus on lymphangioleiomyomatosis and pulmonary Langerhans cell histiocytosis.

Rare Tumors in Children: Progress Through Collaboration

Rare pediatric tumors account for approximately 10% of all childhood cancers, which in themselves are a rare entity. The diverse histologies and clinical behaviors of rare pediatric tumors pose challenges to the investigation of their biologic and clinical features. National and international cooperative groups such as the Rare Tumor Committee of the Children's Oncology Group, Rare Tumors in Pediatric Age Project, and European Cooperative Study Group for Pediatric Rare Tumors have developed several initiatives to advance knowledge about rare pediatric cancers. However, these programs have been only partially effective, necessitating the development of alternative mechanisms to study these challenging diseases. In this article, we review the current national and international collaborative strategies to study rare pediatric cancers and alternative methods under exploration to enhance those efforts, such as independent registries and disease-specific, National Cancer Institute-sponsored clinics.

The argument for a non-operative approach to asymptomatic lung lesions

The controversy surrounding the management of congenital lung malformations (CLMs) centre on how best to manage the increasing population of asymptomatic antenatally detected infants. Should elective surgery be offered? Or is a "watch-and-wait" policy safe? This will be addressed in this review by examining the reported complications of surgery, the risk of symptom development if lesions are left in situ and whether this may alter surgical outcomes, and importantly whether there is any long-term risk of malignancy that can be negated by surgical resection in infancy.

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.

Imaging of congenital lung malformations

Congenital lung malformations are a heterogeneous group of anomalies that involve the lungs and tracheobronchial tree (congenital airway pulmonary malformation, bronchial atresia, bronchogenic cyst, congenital lobar overinflation, pulmonary cyst, hamartoma, pulmonary isomerism and azygous lobe), vascular abnormalities (arteriovenous malformations, anomalous pulmonary venous return, pulmonary artery sling, interrupted pulmonary artery, pulmonary varix, pulmonary vein stenosis and pulmonary lymphangiectasia), or frequently both entities (pulmonary sequestration, pulmonary maldevelopment and scimitar syndrome). Advances in diagnostic imaging (including sonography, multi-detector computer tomography, magnetic resonance imaging and angiography) have increased their detection during both antenatal and postnatal periods, and radiological characterisation, which in turn influence patient counselling and management stratification. An educational illustration of the clinical application in characterisation of these malformations is presented.

Temporal order of RNase IIIb and loss-of-function mutations during development determines phenotype in pleuropulmonary blastoma / DICER1 syndrome: a unique variant of the two-hit tumor suppression model

Pleuropulmonary blastoma (PPB) is the most frequent pediatric lung tumor and often the first indication of a pleiotropic cancer predisposition,  DICER1 syndrome, comprising a range of other individually rare, benign and malignant tumors of childhood and early adulthood. The genetics of  DICER1-associated tumorigenesis are unusual in that tumors typically bear neomorphic missense mutations at one of five specific “hotspot” codons within the RNase IIIb domain of  DICER 1, combined with complete loss of function (LOF) in the other allele. We analyzed a cohort of 124 PPB children for predisposing  DICER1 mutations and sought correlations with clinical phenotypes. Over 70% have inherited or  de novo germline LOF mutations, most of which truncate the  DICER1 open reading frame. We identified a minority of patients who have no germline mutation, but are instead mosaic for predisposing  DICER1 mutations. Mosaicism for RNase IIIb domain hotspot mutations defines a special category of  DICER1 syndrome patients, clinically distinguished from those with germline or mosaic LOF mutations by earlier onsets and numerous discrete foci of neoplastic disease involving multiple syndromic organ sites. A final category of PBB patients lack predisposing germline or mosaic mutations and have sporadic (rather than syndromic) disease limited to a single PPB tumor bearing tumor-specific RNase IIIb and LOF mutations. We propose that acquisition of a neomorphic RNase IIIb domain mutation is the rate limiting event in  DICER1-associated  tumorigenesis, and that distinct clinical phenotypes associated with mutational categories reflect the temporal order in which LOF and RNase IIIb domain mutations are acquired during development.

Temporal order of RNase IIIb and loss-of-function mutations during development determines phenotype in pleuropulmonary blastoma / DICER1 syndrome: a unique variant of the two-hit tumor suppression model

Pleuropulmonary blastoma (PPB) is the most frequent pediatric lung tumor and often the first indication of a pleiotropic cancer predisposition,  DICER1 syndrome, comprising a range of other individually rare, benign and malignant tumors of childhood and early adulthood. The genetics of  DICER1-associated tumorigenesis are unusual in that tumors typically bear neomorphic missense mutations at one of five specific "hotspot" codons within the RNase IIIb domain of  DICER 1, combined with complete loss of function (LOF) in the other allele. We analyzed a cohort of 124 PPB children for predisposing  DICER1 mutations and sought correlations with clinical phenotypes. Over 70% have inherited or  de novo germline LOF mutations, most of which truncate the  DICER1 open reading frame. We identified a minority of patients who have no germline mutation, but are instead mosaic for predisposing  DICER1 mutations. Mosaicism for RNase IIIb domain hotspot mutations defines a special category of  DICER1 syndrome patients, clinically distinguished from those with germline or mosaic LOF mutations by earlier onsets and numerous discrete foci of neoplastic disease involving multiple syndromic organ sites. A final category of PBB patients lack predisposing germline or mosaic mutations and have sporadic (rather than syndromic) disease limited to a single PPB tumor bearing tumor-specific RNase IIIb and LOF mutations. We propose that acquisition of a neomorphic RNase IIIb domain mutation is the rate limiting event in  DICER1-associated  tumorigenesis, and that distinct clinical phenotypes associated with mutational categories reflect the temporal order in which LOF and RNase IIIb domain mutations are acquired during development.

Fibroblast Growth Factor 9 Regulation by MicroRNAs Controls Lung Development and Links DICER1 Loss to the Pathogenesis of Pleuropulmonary Blastoma

Pleuropulmonary Blastoma (PPB) is the primary neoplastic manifestation of a pediatric cancer predisposition syndrome that is associated with several diseases including cystic nephroma, Wilms tumor, neuroblastoma, rhabdomyosarcoma, medulloblastoma, and ovarian Sertoli-Leydig cell tumor. The primary pathology of PPB, epithelial cysts with stromal hyperplasia and risk for progression to a complex primitive sarcoma, is associated with familial heterozygosity and lesion-associated epithelial loss-of-heterozygosity of DICER1. It has been hypothesized that loss of heterozygosity of DICER1 in lung epithelium is a non-cell autonomous etiology of PPB and a critical pathway that regulates lung development; however, there are no known direct targets of epithelial microRNAs (miRNAs) in the lung. Fibroblast Growth Factor 9 (FGF9) is expressed in the mesothelium and epithelium during lung development and primarily functions to regulate lung mesenchyme; however, there are no known mechanisms that regulate FGF9 expression during lung development. Using mouse genetics and molecular phenotyping of human PPB tissue, we show that FGF9 is overexpressed in lung epithelium in the initial multicystic stage of Type I PPB and that in mice lacking epithelial Dicer1, or induced to overexpress epithelial Fgf9, increased Fgf9 expression results in pulmonary mesenchymal hyperplasia and a multicystic architecture that is histologically and molecularly indistinguishable from Type I PPB. We further show that miR-140 is expressed in lung epithelium, regulates epithelial Fgf9 expression, and regulates pseudoglandular stages of lung development. These studies identify an essential miRNA-FGF9 pathway for lung development and a non-cell autonomous signaling mechanism that contributes to the mesenchymal hyperplasia that is characteristic of Type I PPB.

Case 211: pleuropulmonary blastoma in association with cystic nephroma-DICER1 syndrome

HISTORY

A 5-month-old full-term female infant presented to an outside institution with fever and tachypnea. She was born after an uncomplicated pregnancy and delivery, with an uneventful neonatal course. The parents reported a history of persistent tachypnea, grunting, and episodic nonproductive cough with intermittent wheezing since birth. A chest radiograph obtained at the outside hospital prompted transfer to our institution. The patient's medical history was otherwise unremarkable. There was no history of infectious exposure, recurrent infection, aspiration, or choking. Her immunizations were up to date. Physical examination revealed a temperature of 38.1°C, a respiratory rate of 48 breaths per minute, a heart rate of 158 beats per minute, decreased breath sounds on the left side, and mild suprasternal and intercostal retractions. Pertinent laboratory values, including white blood cell count, were normal. On arrival at our institution, unenhanced chest computed tomography (CT) was performed. The patient underwent surgical resection of the left upper lobe. On the basis of pathology results, ultrasonography (US) of the kidneys was performed and revealed a normal right kidney and a cystic lesion in the left kidney. This cyst increased in size, with interval development of a new cyst at 5-month follow-up. Partial nephrectomy of the left kidney was performed.

Cell- and developmental stage-specific Dicer1 ablation in the lung epithelium models cystic pleuropulmonary blastoma

Inherited syndromes provide unique opportunities to identify key regulatory mechanisms governing human disease. We previously identified germline loss-of-function DICER1 mutations in a human syndrome defined by the childhood lung neoplasm pleuropulmonary blastoma (PPB), which arises during lung development. DICER1 regulates many biological processes critical in development and disease pathogenesis. Significant challenges in defining the role of DICER1 in human disease are identifying cause-effect relationships and generating manipulatable systems that model the complexity of organ development and disease pathogenesis. Here we report the generation of a murine model for PPB and demonstrate that precise temporal and cell type-specific Dicer1 ablation is necessary and sufficient for the development of cystic lungs that histologically and phenotypically model PPB. Dicer1 ablation in the distal airway epithelium during early stages of lung development resulted in a cystic lung phenotype indistinguishable from PPB, whereas DICER1 function was not required for development of the proximal airway epithelium or during later stages of organogenesis. Mechanistic studies demonstrate that Dicer1 loss results in epithelial cell death, followed by cystic airway dilatation accompanied by epithelial and mesenchymal proliferation. These studies define precise temporal and epithelial cell type-specific DICER1 functions in the developing lung and demonstrate that loss of these DICER1 functions is sufficient for the development of cystic PPB. These results also provide evidence that PPB arise through a novel mechanism of non-cell-autonomous tumour initiation, in which the genetic abnormality initiating the neoplasm does not occur in the cells that ultimately transform, but rather occurs in a benign-appearing epithelial cell component that predisposes underlying mesenchymal cells to malignant transformation.

Pleuropulmonary blastoma: a report on 350 central pathology-confirmed pleuropulmonary blastoma cases by the International Pleuropulmonary Blastoma Registry

BACKGROUND

Pleuropulmonary blastoma (PPB) has 3 subtypes on a tumor progression pathway ranging from type I (cystic) to type II (cystic/solid) and type III (completely solid). A germline mutation in DICER1 is the genetic cause in the majority of PPB cases.

METHODS

Patients confirmed to have PPB by central pathology review were included, and their clinical characteristics and outcomes were reported. Germline DICER1 mutations were sought with Sanger sequencing.

RESULTS

There were 435 cases, and a central review confirmed 350 cases to be PPB; 85 cases (20%) were another entity. Thirty-three percent of the 350 PPB cases were type I or type I regressed (type Ir), 35% were type II, and 32% were type III or type II/III. The median ages at diagnosis for type I, type II, and type III patients were 8, 35, and 41 months, respectively. The 5-year overall survival (OS) rate for type I/Ir patients was 91%; all deaths in this group were due to progression to type II or III. OS was significantly better for type II versus type III (P = .0061); the 5-year OS rates were 71% and 53%, respectively. Disease-free survival (DFS) was also significantly better for type II versus type III (P = .0002); the 5-year DFS rates were 59% and 37%, respectively. The PPB type was the strongest predictor of outcome. Metastatic disease at the diagnosis of types II and III was also an independent unfavorable prognostic factor. Sixty-six percent of the 97 patients tested had a heterozygous germline DICER1 mutation. In this subset, the DICER1 germline mutation status was not related to the outcome.

CONCLUSIONS

Cystic type I/Ir PPB has a better prognosis than type II, and type II has a better outcome than type III. Surveillance of DICER1 carriers may allow the earlier detection of cystic PPB before its progression to type II or III PPB and thereby improve outcomes.

Pleuropulmonary Blastoma: Evolution of an Entity as an Entry into a Familial Tumor Predisposition Syndrome

Pleuropulmonary blastoma (PPB) is the most common primary malignant neoplasm of the lung in children. Like other solid dysontogenic neoplasms, this tumor typically presents before 7 years of age. The earliest manifestation is the presence of a lung cyst(s), which is usually recognized in the first year of life and is difficult to differentiate on the basis of imaging studies from non-neoplastic cysts of early childhood. From a multilocular cyst, PPB has the potential to progress to a high-grade multipatterned primitive sarcoma. More than 65% of all affected children have a heterozygous germline mutation in DICER1. The DICER1 PPB familial tumor predisposition syndrome is initially recognized in most cases on the basis of PPB alone but also by several other unique and characteristic extrapulmonary tumors, including pediatric cystic nephroma, nasal chondromesenchymal hamartoma, nodular lesions of the thyroid, embryonal rhabdomyosarcoma of the cervix, and ciliary body medulloepithelioma.

Adult pulmonary blastoma: Report of an unusual malignant lung tumor

Pulmonary blastoma is an uncommon lung malignancy, usually presenting itself as a large chest mass causing pain, hemoptysis, cough and dyspnea; however, it is asymptomatic in up to 40% of patients. We present the case and suggestive images of a 37-year-old non-smoking lady with a monophasic pulmonary blastoma located in the lower lobe of the left lung who underwent a left posterolateral thoracotomy with lower lobectomy, hilar and mediastinal node dissection, followed by chemo and radiation therapy. After 36 mo, there is no disease progression and the patient is in good health, clinically stable and without significant chest pain.

Exome sequencing of pleuropulmonary blastoma reveals frequent biallelic loss of TP53 and two hits in DICER1 resulting in retention of 5p-derived miRNA hairpin loop sequences

Pleuropulmonary blastoma is a rare childhood malignancy of lung mesenchymal cells that can remain dormant as epithelial cysts or progress to high-grade sarcoma. Predisposing germline loss-of-function DICER1 variants have been described. We sought to uncover additional contributors through whole exome sequencing of 15 tumor/normal pairs, followed by targeted resequencing, miRNA analysis and immunohistochemical analysis of additional tumors. In addition to frequent biallelic loss  of TP53 and mutations of NRAS or BRAF in some cases, each case had compound disruption of DICER1: a germline (12 cases) or somatic (3 cases) loss-of-function variant plus a somatic missense mutation in the RNase IIIb domain. 5p-Derived microRNA (miRNA) transcripts retained abnormal precursor miRNA loop sequences normally removed by DICER1. This work both defines a genetic interaction landscape with DICER1 mutation and provides evidence for alteration in miRNA transcripts as a consequence of DICER1 disruption in cancer.

DICER1: mutations, microRNAs and mechanisms

Dicer is central to microRNA-mediated silencing and several other RNA interference phenomena that are profoundly embedded in cancer gene networks. Most recently, both germline and somatic mutations in DICER1 have been identified in diverse types of cancer. Although some of the mutations clearly reduce the dosage of this key enzyme, others dictate surprisingly specific changes in select classes of small RNAs. This Review reflects on the molecular properties of the Dicer enzymes in small RNA silencing pathways, and rationalizes the newly discovered mutations on the basis of the activities and functions of its determinants.

DICER1 mutations in childhood cystic nephroma and its relationship to DICER1-renal sarcoma

The pathogenesis of cystic nephroma of the kidney has interested pathologists for over 50 years. Emerging from its initial designation as a type of unilateral multilocular cyst, cystic nephroma has been considered as either a developmental abnormality or a neoplasm or both. Many have viewed cystic nephroma as the benign end of the pathologic spectrum with cystic partially differentiated nephroblastoma and Wilms tumor, whereas others have considered it a mixed epithelial and stromal tumor. We hypothesize that cystic nephroma, like the pleuropulmonary blastoma in the lung, represents a spectrum of abnormal renal organogenesis with risk for malignant transformation. Here we studied DICER1 mutations in a cohort of 20 cystic nephromas and 6 cystic partially differentiated nephroblastomas, selected independently of a familial association with pleuropulmonary blastoma and describe four cases of sarcoma arising in cystic nephroma, which have a similarity to the solid areas of type II or III pleuropulmonary blastoma. The genetic analyses presented here confirm that DICER1 mutations are the major genetic event in the development of cystic nephroma. Further, cystic nephroma and pleuropulmonary blastoma have similar DICER1 loss of function and 'hotspot' missense mutation rates, which involve specific amino acids in the RNase IIIb domain. We propose an alternative pathway with the genetic pathogenesis of cystic nephroma and DICER1-renal sarcoma paralleling that of type I to type II/III malignant progression of pleuropulmonary blastoma.

Judicious DICER1 testing and surveillance imaging facilitates early diagnosis and cure of pleuropulmonary blastoma

Pleuropulmonary blastoma (PPB) and Sertoli-Leydig cell tumor (SLCT) are both associated with germline mutations in DICER1. In this brief report, a maternal history of SLCT led to identification of a deleterious DICER1 mutation in the patient and her asymptomatic infant. Radiographic screening revealed a large Type I PPB, which was completely resected. Identification of DICER1 mutation carriers and imaging of children at risk for PPB may allow detection of PPB in its earliest and most curable form, leading to increased likelihood of surgical cure and decreased risks of treatment-related late effects.

Nasal chondromesenchymal hamartomas arise secondary to germline and somatic mutations of DICER1 in the pleuropulmonary blastoma tumor predisposition disorder

Nasal chondromesenchymal hamartoma (NCMH) is a rare nasal tumor that typically presents in young children. We previously reported on NCMH occurrence in children with pleuropulmonary blastoma (PPB), a rare pulmonary dysembryonic sarcoma that is the hallmark neoplasm in the PPB-associated DICER1 tumor predisposition disorder. Original pathologic materials from individuals with a PPB, PPB-associated tumor and/or a DICER1 mutation were centrally reviewed by the International PPB Registry. Paraffin-embedded NCMH tumor tissue was available in three cases. Laser-capture microdissection was used to isolate mesenchymal spindle cells and cartilage in one case for Sanger sequencing of DICER1. Nine patients (5F/4M) had PPB and NCMH. NCMH was diagnosed at a median age of 10 years (range 6-21 years). NCMH developed 4.5-13 years after PPB. Presenting NCMH symptoms included chronic sinusitis and nasal congestion. Five patients had bilateral tumors. Local NCMH recurrences required several surgical resections in two patients, but all nine patients were alive at 0-16 years of follow-up. Pathogenic germline DICER1 mutations were found in 6/8 NCMH patients tested. In 2 of the patients with germline DICER1 mutations, somatic DICER1 missense mutations were also identified in their NCMH (E1813D; n = 2). Three additional PPB patients developed other nasal lesions seen in the general population (a Schneiderian papilloma, chronic sinusitis with cysts, and allergic nasal polyps with eosinophils). Two of these patients had germline DICER1 mutations. Pathogenic germline and somatic mutations of DICER1 in NCMH establishes that the genetic etiology of NCMH is similar to PPB, despite the disparate biological potential of these neoplasms.

Cystic lung lesions in newborns and young children: differential considerations and imaging

Numerous diverse entities produce cystic lung changes in neonates and young children. This review provides an evidence-based, age-appropriate, differential diagnostic framework to use when confronted with pulmonary cystic changes. The categories of diseases that have been discussed include congenital cystic bronchopulmonary malformations, neoplastic conditions, infections, collagen or soft tissue abnormalities, and mimics of cystic lung disease. An understanding of the pathophysiology, imaging appearance, and demographics of these entities is essential in guiding optimal care. Important educational points include differentiating bronchopulmonary malformations from neoplasms and the management and surveillance of lung cysts in young children.

Identification of novel ALK rearrangement A2M-ALK in a neonate with fetal lung interstitial tumor

Fetal lung interstitial tumor (FLIT) is a recently reported type of congenital lung lesion comprising solid and cystic components. The pathological features include unique interstitial mesenchyme-based cell proliferation, and differ from other neoplasms represented by pleuropulmonary blastoma or congenital peribronchial myofibroblastic tumor. FLIT is extremely rare and its gene expression profile has not yet been reported. We provide the first report of a novel chromosomal rearrangement resulting in α-2-macroglobulin (A2M) and anaplastic lymphoma kinase (ALK) gene fusion in a patient with FLIT. The tumor cells contained a t(2;12)(p23;p13) and were mesenchymal in origin (e.g., inflammatory myofibroblastic tumors), suggesting the involvement of ALK in this case of FLIT. Break apart fluorescence in situ hybridization demonstrated chromosomal rearrangement at ALK 2p23. Using 5'-rapid amplification of cDNA ends, we further identified a novel transcript fusing exon 22 of A2M to exon 19 of ALK, which was confirmed by reverse-transcription polymerase chain reaction. The corresponding chimeric gene was subsequently confirmed by sequencing, including the genomic break point between intron 22 and 18 of A2M and ALK, respectively. Discovery of A2M as a novel ALK fusion partner, together with the involvement of ALK, provides new insights into the pathogenesis of FLIT, and suggests the potential for new therapeutic strategies based on ALK inhibitors.

Type III pleuropulmonary blastoma in a 7-month-old female baby with impending respiratory failure: a case report

Introduction

Pleuropulmonary blastoma is a very rare, aggressive, embryonal pulmonary neoplasm which mostly affects children under the age of 5. According to the histopathological features, three subtypes of pleuropulmonary blastoma have been recognized: type I (purely cystic), type II (grossly visible cystic and solid elements) and type III (purely solid). Characteristics of type I and type II blastoma allow an earlier diagnosis compared with type III. Here we present a case report of an unusual presentation of type III pleuropulmonary blastoma.

Case presentation

We describe the case of a 7-month-old female baby of Italian mother and Kurdish father who was diagnosed with type III pleuropulmonary blastoma, which entirely occupied her right hemithorax.

Conclusions

The reported case is an unusual presentation because type III pleuropulmonary blastoma typically occurs in older children. The complete re-expansion of her residual, previously totally compressed, right lung observed immediately after the resection of the lesion suggests an atypical rapid growth of this embryonal tumor in the late phase of gestation or after delivery. This case report suggests that, in addition to other childhood tumors, type III pleuropulmonary blastoma should be included in the differential diagnosis of solid nonhomogeneous thoracic large masses, compressing the mediastinal and chest wall structures in infants. This is an original case report of interest for several specialities such us pediatrics, radiology, surgery and oncology.

Biallelic DICER1 mutations in sporadic pleuropulmonary blastoma

Pleuropulmonary blastoma (PPB) is a rare pediatric malignancy whose pathogens are poorly understood. Recent reports suggest that germline mutations in the microRNA-processing enzyme DICER1 may contribute to PPB development. To investigate the genetic basis of this cancer, we performed whole-exome sequencing or targeted deep sequencing of multiple cases of PPB. We found biallelic DICER1 mutations to be very common, more common than TP53 mutations also found in many tumors. Somatic ribonuclease III (RNase IIIb) domain mutations were identified in all evaluable cases, either in the presence or absence of nonsense/frameshift mutations. Most cases had mutated DICER1 alleles in the germline with or without an additional somatic mutation in the remaining allele, whereas other cases displayed somatic mutations exclusively where the RNase IIIb domain was invariably affected. Our results highlight the role of RNase IIIb domain mutations in DICER1 along with TP53 inactivation in PPB pathogenesis.

Spontaneous pneumothorax in a teenager with prior congenital pulmonary airway malformation

Congenital pulmonary airway malformation (CPAM), previously referred to as congenital cystic adenomatoid malformation (CCAM), is a developmental malformation of the lower respiratory tract and the most commonly reported congenital lung lesion. Affected patients typically present with respiratory distress in the neonatal period from expanding cysts and resulting compression of surrounding lung parenchyma. However, some patients also remain asymptomatic until later in life. In this report, we present a case of CPAM requiring emergent left lower lobectomy at the first day of life that remained asymptomatic until the patient developed a spontaneous pneumothorax 18 years later. Our patient's presentation with an isolated spontaneous pneumothorax at age 18 does not appear to have been previously reported. In addition, there are several aspects of this case that represent atypical features of CPAM. After an extensive literature search, few reports exist describing any long-term complications of CPAM following neonatal lobectomy. Chest imaging in our patient demonstrated residual left basilar bullae and there was a moderate fixed obstructive/restrictive defect on pulmonary function testing. His risk for recurrent pneumothorax or infectious complications is unknown based on minimal published information on long-term outcomes or complications in patients with resected CPAM lesions. We conclude that follow up of all CPAM patients should include an evaluation for evidence of residual lung disease both with spirometric testing and chest imaging. Furthermore, concern for infectious complications or symptomatic obstructive lung disease should likewise be considered.

Thoracoscopic lobectomy for type I pleuropulmonary blastoma in an infant

Pleuropulmonary blastoma (PPB) is a rare, aggressive, intrathoracic mesenchymal neoplasm associated with cystic lung lesions. The authors describe an 8-month-old male who underwent thoracoscopic left upper lobectomy for a cystic lung lesion initially diagnosed as congenital pulmonary airway malformation. Pathology revealed type I PPB.

Clinicopathological and extensive immunohistochemical study of a type II pleuropulmonary blastoma

Pleuropulmonary blastoma (PPB) is a rare malignant dysontogenetic neoplasm primarily affecting younger children, even in newborns with an unfavorable outcome. PPB is histologically composed of a primitive, variably mixed blastematous and sarcomatous components, and exclusively subclassified as type I (purely cystic), type II (both cystic and solid elements) and type III (completely solid) by increasing histological evidence of malignancy. At present, well-documented cases or cases of truly precise presentation of either pathological or immunohistochemical findings in PPB are rare. The authors report one case of PPB in a 44-month-old child presenting as a solid and cystic mass with special emphasis on its radiological, histopathological and immunohistochemical aspects. The histological diagnosis was PPB, which would belong to the type II category.

Neonatal cancer

Neonatal cancer is rare and comprises a heterogeneous group of neoplasms with substantial histological diversity. Almost all types of paediatric cancer can occur in fetuses and neonates; however, the presentation and behaviour of neonatal tumours often differs from that in older children, leading to differences in diagnosis and management. The causes of neonatal cancer are unclear, but genetic factors probably have a key role. Other congenital abnormalities are frequently present. Teratoma and neuroblastoma are the most common histological types of neonatal cancer, with soft-tissue sarcoma, leukaemia, renal tumours, and brain tumours also among the more frequent types. Prenatal detection, most often on routine ultrasound or in the context of a known predisposition syndrome, is becoming more common. Treatment options pose challenges because of the particular vulnerability of the population. Neonatal cancer raises diagnostic, therapeutic, and ethical issues, and management requires a multidisciplinary approach.

DICER1-pleuropulmonary blastoma familial tumor predisposition syndrome: a unique constellation of neoplastic conditions

Germline mutations in DICER1 are associated with increased risk for a wide variety of neoplastic conditions, including pleuropulmonary blastoma (PPB), cystic nephroma, nasal chondromesenchymal hamartoma, ovarian Sertoli-Leydig cell tumors, botryoid embryonal rhabdomyosarcoma of the uterine cervix, ciliary body medulloepithelioma, pineoblastoma, pituitary blastoma and nodular thyroid hyperplasia or thyroid carcinoma. These tumors may be seen in isolation or in constellation with other characteristic tumor types in individuals or family members. Here we describe the medical history of a child with a heterozygous, loss of function germline DICER1 mutation and multiple tumors associated with the syndrome.. Although germline mutations in DICER1 are rare, tumors of these types will be seen by practicing pathologists and should prompt consideration of an underlying DICER1 mutation.

FGF10 Signaling differences between type I pleuropulmonary blastoma and congenital cystic adenomatoid malformation

Background

Type I pleuropulmonary blastoma (PPB) and congenital cystic adenomatoid malformation of the lung (CCAM) are cystic lung diseases of childhood. Their clinical and radiological presentations are often similar, and pathologic discrimination remains difficult in many cases. As a consequence, type I PPB and CCAM are frequently confused, leading to delayed adequate management for type I PPB. Recent studies have suggested a role for fibroblast growth factor (FGF) 10 signal pathway in CCAM pathogenesis. The objective of our study was to determine whether FGF10 signaling differs between CCAM and type I PPB.

Methods

Immunohistochemical studies were performed for expression of FGF10, its receptor FGFR2b, and its inhibitor sonic hedgehog (SHH) in focal type I PPB (n=6), CCAM type I (n=7), CCAM type II (n=7), and control lungs (n=5).

Results

FGF10, FGFR2b, and SHH expressions differed markedly between type I PPB and both types of CCAM. Type I and type II CCAM cystic walls expressed FGF10, FGFR2b, and SHH, whereas staining was absent or poor in type I PBB cystic walls. Expression of FGF10, FGFR2b, and SHH did not differ between CCAM cystic walls and control airway walls.

Conclusions

These findings show that immunohistochemistry with FGF10, FGFR2b, or SHH could be useful in differentiating CCAM from type I PPB, when a child presents with a focal cystic lung lesion. The absence of strong expression of FGF10, FGFR2b, and/or SHH makes the diagnosis of CCAM very doubtful.

Shall all congenital cystic lung malformations be removed? the case in favour

The need to systematically remove congenital cystic lung lesions is based on three main arguments. First, cystic malformations are often considered as congenital cystic adenomatoid malformations (CCAM), while other less favorable diagnoses are possible, such as pleuropulmonary blastoma. Only postsurgical pathological analysis allows diagnosis. Second, there are clinical and biological arguments for considering macrocystic lesions as likely to degenerate. The only prevention is surgical removal. Finally, there is no recommendation on how to follow these children, in the absence of removal, causing unnecessary family stress. This seems unjustified, compared to a feasibility of thoracoscopic removal in most cases.

An unusual case of pleuropulmonary blastoma in a child with jejunal hamartomas

We report a rare case of 9-month-old girl who presented with a choking episode and was found to have an incidental finding of a lung cyst and iron deficiency anemia leading to the diagnosis of pleuropulmonary blastoma (PPB) and a jejunal hamartoma. Our patient is the eighth that has been reported with the association of PPB with jejunal hamartoma and the first one in the radiological literature. PPB is the pulmonary analog of other dysontogenetic neoplasms in childhood. A biological sequence has been described with the three types of PPB to be interrelated as part of pathologic progression. PPB can be associated with other cysts and/or neoplasms in different organs. PPB is part of a hereditary neoplasia predisposition syndrome in up to 40% of cases. Mutations in DICER gene have been described with PPB. Hence, a pediatric patient diagnosed with PPB should be screened for associated conditions during childhood and adolescence including intestinal polyps. Obtaining family history for other neoplasms or cysts is important information that should raise the possibility of PPB in pediatric patients with cystic lung lesions. The presence of this syndrome should alert the clinician to screen and follow up patients and their relatives.

Type 2 congenital pulmonary airway malformation and congenital nephrotic syndrome: report of a new association

Type 2 congenital pulmonary airway malformation (CPAM) has been reported in association with many other congenital anomalies. To the best of our knowledge, however, an association of type 2 CPAM with congenital nephrotic syndrome has not been heretofore reported. We present the 1st report of such an association in a boy who had a prenatal diagnosis of cystic lung malformation and was found to have congenital nephrotic syndrome (diffuse mesangial sclerosis) at 1 month of age. A prenatal ultrasonogram had also shown oligohydramnios, and additionally the child had cleft lip and palate. There was no family history of childhood renal or pulmonary disease, and genetic testing for genes mutated in congenital nephrotic syndrome was negative.

Childhood craniopharyngioma: 20-year institutional experience in Western Australia

AIM

A retrospective audit was undertaken to evaluate modes of presentation and treatment outcomes for craniopharyngioma in a single paediatric institution over a 20-year period.

METHODS

A search of the neurosurgical and histopathological databases for patients under 21 years of age treated for craniopharyngioma between 1990 and 2010 was performed at our institution. The clinical records of eligible patients were reviewed and information regarding presentation, medical and surgical management and post-treatment outcome were extracted and collated.

RESULTS

Of 10 evaluable patients, the commonest presenting symptoms were headache and visual impairment. Clinical and biochemical evaluation undertaken prior to surgery revealed visual dysfunction in 70% and pituitary deficit in 30%. Gross total resection was achieved in 40% but was curative in only 20%. The remaining 80% required further surgical and/or radiotherapeutic intervention. Seven patients had radiation therapy with stabilisation in 70%. Multiple pituitary hormone deficiency evolved in all patients over time, while visual impairment worsened in 30% post-operatively and improved in 20%. Obesity was present in 50% after a mean follow-up interval of 5.6 years and was apparent within 1 year of initial surgery in 30%. Although neurocognitive, psychological and behavioural problems were noted for some patients during medical review, only 20% of patients were formally assessed.

CONCLUSIONS

Craniopharyngioma is associated with significant long-term morbidity. Attention to an integrated care pathway that includes standardised neurocognitive and psychological and behavioural assessment would facilitate early appropriate intervention and support leading to an improved quality of life for children with craniopharyngioma.