Pleuropulmonary blastoma (PPB) with central nervous system metastasis: case report, imaging findings, and review of literature.

Pleuropulmonary blastoma (PPB) is a very rare tumor of the chest seen predominantly in young children with great heterogeneity and clinical, biochemical, and biological complexity and recognized, described, and classified as distinct from the pulmonary blastoma typically encountered in adults. Unfortunately, it has a poor and dismal prognosis and is mainly classified as cystic (type 1), mixed type (type 2), and solid (type 3). Herein, we present one case of PPB type 2 presenting clinically with a right pulmonary abscess, a rare clinical presentation of PPB, which was initially treated with surgery, and after approximately 1 year of follow-up, pulmonary rest-recurrence and central nervous system secondary deposits were detected. When a large pleural-based mass is identified in a young child, PPB should also be considered, especially in a patient with a positive oncological family history. Suggestive findings include the absence of chest wall invasion, presence of pleural fluid, right-sided location, and heterogeneous native (NECT) low attenuation with variable postcontrast enhancement. The authors believe that a modern therapeutic approach should consider these results for a better understanding of the genetic nature and complex mechanism and process of PPB disease development (both clinical and preclinical data concerning PPB pathophysiology are still lacking and are not completely understood) so that it would be possible to establish new possible therapeutic options (i.e. nuclear medicine theranostics in PPB treatment, developments and innovation in FLASH radiotherapy and proton therapy) and approaches, and so that, given the severity of the disease, it would be possible to indicate the importance of genetic testing and counseling of close relatives. In line with the previous, the rapid development of artificial intelligence could potentially bring the development of a novel fusion of radio mics and semantic features and MRI-based machine learning in distinguishing PPB from similar pathology.

Predictive Factors of Mortality in Pediatric Pleuropulmonary Blastoma: A Surveillance Epidemiology and End Results Database Analysis.

Purpose: Pleuropulmonary blastoma (PPB) is a rare malignancy associated with mutations in the DICER1 gene. Early-stage disease (PPB type I) mimics cystic lung malformations and develops in infants <1 year of age, and PPB type II and III arises in older children. The objective of this study was to analyze predictive factors of mortality in pediatric patients aged 0-19 years diagnosed with PPB between 2000 and 2019 in the USA. Methods: A retrospective analysis of pediatric patients (0-19 years) in the Surveillance Epidemiology and End Results database was conducted from 2000 to 2019 with a diagnosis of PPB using International Classification of Disease for Oncology, third edition code 8973/3 and rare tumor code 45. Demographics, incidence, staging, treatment, and mortality were extracted. A mortality risk predictive equation was developed using logistic regression. Statistical analysis was conducted through Microsoft Excel Analysis ToolPak and Solver. Results: There were a total of 71 new cases of PPB during the study period, with 16 (22%) deaths. The demographic analysis demonstrated that 40/71 (56.3%) patients were female, 57/71 (80.3%) were White, and 64/71 (90.1%) resided in metropolitan areas. Regression analysis demonstrated a statistically significant correlation between mortality and stage (P = 0.029), need for chemotherapy (P = 0.047), and female sex (P = 0.019). There was no significant correlation between mortality and need for radiation, race, or age at diagnosis. Multiple logistic regression analysis generated a predictive equation of mortality dependent on the stage of PPB, need for chemotherapy, and sex. This equation has an 82% accuracy, 81% sensitivity, and an 18% false positive rate. Conclusion: PPB is a rare disease. Distinguishing PPB from benign cystic lung malformations in infancy is important to avoid progression to Type II and III PPB. Advanced stages of PPB have a greater need for systemic chemotherapy and radiation with a poor prognosis.

Pleuropulmonary Blastoma: A Report of Two Rare Cases.

Pleuropulmonary blastoma (PPB) is a rare malignant tumor arising from the lung and pleura. It has three types based on the solid and cystic components. The prognosis of PPB varies depending on the type. Here, we present two female patients who come with complaints of breathlessness. Contrast-enhanced computed tomography (CECT) chest showed a pleural-based mass. Biopsy from the pleural-based mass showed a tumor with features of the malignant mesenchymal tumor. Tumor cells in both cases were positive for vimentin and negative for PanCK. In addition, tumor cells of one case showed positive for BCL2 and α-1 antitrypsin and negative for desmin, CD99, NSE, and p53. Tumor cells of another case are negative for CD99, WT-1, S100, synaptophysin, and chromogranin. In addition, some of the cells have abundant eosinophilic cytoplasm. Desmin shows positive in many cells and highlights rhabdomyoblasts. Morphological and immunohistochemical findings were correlated with the CECT diagnosis of PPB. Both cases were started on neoadjuvant chemotherapy and kept under follow-up. Both the patient's condition improved.

Congenital Chest Lesions and Interventions.

Anomalies of the fetal chest require advanced imaging with ultrasound and MR imaging as well as expertise on the part of the interpreting pediatric radiologist. Congenital diaphragmatic hernia and congenital lung malformation are the most frequently seen, and in both conditions, the radiologist should provide both detailed anatomic description and measurement data for prognostication. This article provides a detailed approach to imaging the anatomy, in-depth explanation of available measurements and prognostic value, and keys to identifying candidates for fetal intervention. Less common congenital lung tumors and mediastinal and chest wall masses are also reviewed.

Type II pleuropulmonary blastoma in a fetus: case report of a rare mesenchymal mediastinal tumor and literature review.

Mediastinal tumors are exceedingly rare during fetal development, presenting significant diagnostic challenges and potentially leading to severe outcomes such as stillbirth or metastatic disease if not promptly identified and managed. Pleuropulmonary blastomas are primitive mesenchymal tumors often linked to mutations in the DICER1 gene, indicating a hereditary pattern associated with other common adult neoplasms with dominant inheritance. This report describes a case involving a 20-year-old Caucasian woman whose pregnancy was complicated by a stillbirth in the second trimester. Initial suspicions of a mediastinal tumor arose from blood tests and ultrasound examinations during pregnancy surveillance. However, the definitive diagnosis of a type II pleuropulmonary blastoma was established through a pathological examination at autopsy. This case underscores the complexities of diagnosing fetal mediastinal tumors and contributes to the sparse literature on neonatal pleuropulmonary blastomas. Our comprehensive review of the differential diagnoses and literature emphasizes the unique characteristics of pleuropulmonary blastoma and its similarities to other soft tissue sarcomas, enhancing understanding of their clinical and genetic profiles.

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

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

Histone H3 trimethylation on lysine 27 immunostaining pattern in DICER1-associated tumors.

Background: DICER1-associated tumors are heterogeneous and affect several organs. DICER1-associated primary intracranial sarcoma is associated with histone H3 trimethylation on lysine 27 (H3K27me3) loss in nucleus by immunohistochemistry. Methods: We explored the H3K27me3 immunostaining pattern in other DICER1-associated tumors. Twelve tumors from eleven patients with confirmed DICER1 mutations (sporadic and germline) data from a pancancer next-generation sequencing panel, and four tumors of pleuropulmonary blastoma (PPB) were retrieved from our database and stained with anti-H3K27me3 antibody. Results: The H3K27me3 expression in the nucleus showed heterogeneous mosaic loss in neoplastic Sertoli cell components in three of the five cases of moderately to poorly differentiated Sertoli-Leydig cell tumors. Among two tumors of DICER1-associated primary intracranial sarcoma, one showed complete loss of H3K27me3 in all neoplastic cells, whereas the other showed mosaic loss in the sarcomatous spindle cells. One DICER1-associated tumor with epithelial and mesenchymal differentiation, including pulmonary blastoma and PPB, showed mosaic loss of glandular epithelial and mesenchymal components. Four cases of type II PPB and a single case of type III PPB showed a similar mosaic loss of H3K27me3 staining restricted to large spindle cell components. All other components in all tumors-including Leydig cells; the areas of epithelial, cartilaginous, and rhabdomyomatous differentiation; and all cells of the remaining three cases (one papillary thyroid carcinoma and two cases of PPB type I)-demonstrated retained H3K27me3 staining. Conclusions: H3K27me3 expression is not universally lost in DICER1-associated tumors and thus is not predictive of DICER1 mutation status. The mosaic regional loss of H3K27me3 immunostaining is consistent in PPB type II and III, which can be a helpful diagnostic marker for these tumors and suggests a similarity to DICER1-associated intracranial sarcoma.

Patient Characteristics, Treatment, and Survival in Pleuropulmonary Blastoma: An Analysis from the National Cancer Database.

Pleuropulmonary blastoma (PPB) is a rare childhood tumor originating from the lung or pleura, typically treated with surgery, chemotherapy (CTx), and/or radiation therapy (RTx). This study aimed to assess patient and tumor features, treatment methods, and survival rates in PPB. We retrospectively analyzed PPB patients under 18 from 2004 to 2019, using the National Cancer Database (NCDB). We assessed 5-year overall survival (OS) rates based on disease presentation and treatment regimens, using Kaplan-Meier curves and Cox proportional regression. Among 144 cases identified, 45.9% were female, with a median age of 2 years (interquartile range 1-3). In all, 62.5% of tumors originated from the lung, and 10.4% from the pleura. Moreover, 6.9% were bilateral, and the median tumor size was 8.9 cm, with 4.2% presenting with metastases. The 5-year OS rate was 79.6%, with no significant change over time (2004-2009, 77.6%; 2010-2014, 90.8%; 2015-2019, OS 75.3%; p = 0.08). In all, 5.6% received CTx alone, 31.3% surgery alone, 45.8% surgery/CTx, and 17.4% surgery/CTx/RTx. The OS rates were comparable between the surgery/CTx/RTx (80.0%) and surgery/CTx (76.5%) groups (adjusted Hazard Ratio, 1.72; 95% CI, 0.57-5.19; p = 0.34). Therefore, due to the unchanged survival rates over time, further prospective multicenter studies are needed to determine the optimal multimodal treatment regimens for this rare pediatric tumor.

A rare case of type III pleuropulmonary blastoma infiltrating the left heart in an 11-year-old girl.

INTRODUCTION AND IMPORTANCE: Pleuropulmonary blastoma (PPB) is a rare primary malignant tumor in the chest that mainly occurs in children <6 years of age. Vascular extensions are even rarer, approximately 3 % of types II and III PPB, and have fatal complications. The patients of reported cases who had tumor extension to the heart are younger than three years old, whereas in this case, we reported an 11-year-old girl who was of school age. This case report aims to describe a rare case of a type III Pleuropulmonary Blastoma infiltrating the left heart of a school-age girl. CASE PRESENTATION: An 11-year-old girl presented at an emergency department with two months of progressive dyspnea with malnutrition. A fused mass was found in LA on an echocardiogram along with moderate MR, severe MS, and mild pericardial effusion. CT scan showed a massive pleural effusion with a solid mass in the left lung obstructing the left bronchial tree, accompanied by the expansion of the tumor mass into the left pulmonary vein and LA. CLINICAL DISCUSSION: Total removal of the tumor was performed, aided by cardiopulmonary bypass. Type III PPB was confirmed histopathologically. CONCLUSION: PPB is a rare, aggressive tumor that has three types. Various manifestations can occur in line with the presence of metastases. The treatment consists of aggressive surgery and chemotherapy. Because of its poor prognosis, prompt recognition of the involvement of the cardiac chamber and great vessels in type III PPB should be considered before surgery.

Cytomorphologic and immunocytochemical characterization of pediatric pleuropulmonary blastoma with a comprehensive review of the literature.

INTRODUCTION: Pleuropulmonary blastoma (PPB) is a rare, aggressive, primary intrathoracic malignancy typically seen in infancy and early childhood. Accurate distinction from congenital cystic lung lesions is crucial due to significant prognostic and therapeutic differences. Cytologic features have rarely been described. Establishing a cytodiagnosis is challenging owing to its rarity, lack of awareness, and multiple morphologic mimics. MATERIALS AND METHODS: This was a retrospective study conducted over 8 years. The histopathology and cytopathology databases were searched for all pediatric PPB cases. The corresponding cytologic samples were reviewed to identify characteristic features that can help distinguish PPB from its mimics. RESULTS: There was a total of six cases of pediatric PPB reported during the study period. Of these, four (66.7%) presented as intrathoracic, and two (33.3%) as pleural-based masses. Cytology smears showed discretely scattered and perivascular arrangements of round-oval tumor cells with background eosinophilic stromal material. The tumor cells were mildly pleomorphic (n = 3) with round nuclei, fine chromatin, inconspicuous nucleoli, and scanty cytoplasm; however, three cases showed marked anaplasia, and one each showed necrosis and rhabdoid differentiation. On immunocytochemistry (4/6), these were positive for vimentin and desmin and negative for WT1, chromogranin, SALL4, cytokeratin, CD45, and CD99. FISH (1/6) did not show N-Myc amplification. CONCLUSIONS: Knowledge of the characteristic cytomorphological and immunocytochemical features of PPB is vital to establish a prompt and accurate cytodiagnosis with appropriate clinicoradiologic correlation.

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

BACKGROUND: Distinguishing congenital pulmonary airway malformations (CPAMs) from pleuropulmonary blastoma (PPB) can be challenging. Previously diagnosed patients with CPAM may have been misdiagnosed and we may have missed DICER1-associated PPBs, a diagnosis with important clinical implications for patients and their families. To gain insight in potential misdiagnoses, we systematically assessed somatic DICER1 gene mutation status in an unselected, retrospective cohort of patients with a CPAM diagnosis. METHODS: In the Amsterdam University Medical Center (the Netherlands), it has been standard policy to resect CPAM lesions. We included all consecutive cases of children (age 0-18 years) with a diagnosis of CPAM between 2007 and 2017 at this center. Clinical and radiographic features were reviewed, and DICER1 gene sequencing was performed on DNA retrieved from CPAM tissue samples. RESULTS: Twenty-eight patients with a surgically removed CPAM were included. CPAM type 1 and type 2 were the most common subtypes (n = 12 and n = 13). For 21 patients a chest CT scan was available for reassessment by two pediatric radiologists. In 9 patients (9/21, 43%) the CPAM subtype scored by the radiologists did not correspond with the subtype given at pathology assessment. No pathogenic mutations and no copy number variations of the DICER1 gene were found in the DNA extracted from CPAM tissue (0/28). CONCLUSIONS: Our findings suggest that the initial CPAM diagnoses were correct. These findings should be validated through larger studies to draw conclusions regarding whether systematic DICER1 genetic testing is required in children with a pathological confirmed diagnosis of CPAM or not. LEVEL OF EVIDENCE: Level IV.

Infantile type I pleuropulmonary blastoma presenting with dyspnea due to compression by pneumothorax and an occupying tumor: a case report.

BACKGROUND: Pleuropulmonary blastoma (PPB) is an extremely rare and malignant pediatric lung tumor. Purely cystic PPB has a more favorable prognosis than solid PPB, but may be difficult to distinguish from a certain type of "benign" congenital pulmonary airway malformation before and during surgery. The influence of tumor rupture on long life prognosis has not been clarified in detail. CASE PRESENTATION: A 5-month-old boy underwent emergency transfer from another hospital due to a left thoracic cystic lesion and left pneumothorax detected on chest radiography performed for persistent wheeze and cough. Contrast-enhanced computed tomography of the chest revealed marked deviation of the mediastinum to the right due to a giant cystic lesion and pneumothorax. Thoracotomy was performed on hospital day 2. A cystic lesion had developed from the distal alveolar region of lower lobe of the left lung and the tumor showed a tiny adhesion to the left diaphragm and a tiny rupture near the adhesion. Partial lung excision including the cyst and scraping of the adhesion were performed. Histopathological investigations revealed immature blast cell-like mesenchymal cells and differentiated striated muscle cells in a dense cambium layer were found under the epithelium of the cystic lesion. Type I PPB was diagnosed. CONCLUSIONS: Surgery should be performed with the possibility of type I PPB in mind when an extrapulmonary cystic lung lesion is found. Since issues such as the pathogenesis and long-term prognosis of ruptured cases remain unclear, continued careful follow-up of this case will be required.

Rare Tumors: Opportunities and challenges from the Children's Oncology Group perspective.

While all childhood cancers are rare, tumors that are particularly infrequent or underrepresented within pediatrics are studied under the umbrella of the Children's Oncology Group Rare Tumor committee, divided into the Retinoblastoma and Infrequent Tumor subcommittees. The Infrequent Tumor subcommittee has traditionally included an emphasis on globally rare tumors such as adrenocortical carcinoma, nasopharyngeal carcinoma, or those tumors that are rare in young children, despite being common in adolescents and young adults, such as colorectal carcinoma, thyroid carcinoma, and melanoma. Pleuropulmonary blastoma, gonadal stromal tumors, pancreatic tumors including pancreatoblastoma, gastrointestinal stromal tumor, nonmelanoma skin cancers, neuroendocrine tumors, and desmoplastic small round cell tumors, as well as other carcinomas are also included under the heading of the Children's Oncology Group Rare Tumor committee. While substantial challenges exist in rare cancers, inclusion and global collaboration remain key priorities to ensure high quality research to advance care.

Assessing the role of positron emission tomography and bone scintigraphy in imaging of pleuropulmonary blastoma (PPB): A report from the International PPB/DICER1 Registry.

BACKGROUND: Pleuropulmonary blastoma (PPB) is the most common primary lung neoplasm of infancy and early childhood. Given the rarity of PPB, the role of positron emission tomography (PET) and bone scintigraphy (bone scans) in diagnostic evaluation and surveillance has not been documented to date. Available PET and bone scan data are presented in this study. PROCEDURES: Patients with PPB enrolled in the International PPB/DICER1 Registry and available PET imaging and/or bone scan reports were retrospectively abstracted. RESULTS: On retrospective analysis, 133 patients with type II and III (advanced) PPB were identified with available report(s) (PET scan only = 34, bone scan only = 83, and both bone scan and PET = 16). All advanced primary PPB (n = 11) and recurrent (n = 8) tumors prior to treatment presented with 18 F-fluorodeoxyglucose (FDG)-avid lesions, with median maximum standardized uptake values of 7.4 and 6.7, respectively. False positive FDG uptake in the thorax was noted during surveillance (specificity: 59%). Bone metastases were FDG-avid prior to treatment. Central nervous system metastases were not discernable on PET imaging. Sensitivity and specificity of bone scans for metastatic bone disease were 89% and 92%, respectively. Bone scans had a negative predictive value of 99%, although positive predictive value was 53%. Four patients with distant bone metastases had concordant true positive bone scan and PET. CONCLUSION: Primary, recurrent, and/or extracranial metastatic PPB presents with an FDG-avid lesion on PET imaging. Additional prospective studies are needed to fully assess the utility of nuclear medicine imaging in surveillance for patients with advanced PPB.

A pleuropulmonary blastoma type III in a 4-month-old infant: First case report in Syria.

INTRODUCTION: Pleuropulmonary blastoma is a rare, aggressive intrathoracic neoplasm of early childhood. CASE PRESENTATION: We report a case of a 4-month-old male baby who has presented with recurrent respiratory infections since birth. A surgical team was consulted due to abnormal opacification observed on a chest X-ray. An enhanced-contrast CT scan of the chest revealed a heterogenous, well-delineated mass measuring about 3,8 × 6 cm in the posterior mediastinum. A left posterolateral thoracotomy was performed. The mass was separated from the lung parenchyma, located behind the parietal pleura, and adherent to the chest wall and superior ribs. The lesion was totally removed. Histologically, the lesion was a pleuropulmonary blastoma type III. Currently, the patient is on a 6-month course of chemotherapy. CLINICAL DISCUSSION: The aggressive, insidious behavior of PPB requires a high index of suspicion for diagnosis. The clinical manifestations and imaging modalities are atypical and nonspecific. However, PPB should be kept in mind when a huge solid or cystic mass is observed in the lung field on imaging. CONCLUSION: Extrapulmonary pleuropulmonary blastoma is a very rare entity characterized by highly aggressive behavior and a poor prognosis. Early excision of thoracic cystic lesions in children is warranted regardless of the symptoms to avoid future mishaps.

Children's Oncology Group's 2023 blueprint for research: Rare tumors.

The Children's Oncology Group (COG) Rare Tumor Committee includes the Infrequent Tumor and Retinoblastoma subcommittees, encompassing a wide range of extracranial solid tumors that do not fall within another COG disease committee. Current therapeutic trial development focuses on nasopharyngeal carcinoma, adrenocortical carcinoma, pleuropulmonary blastoma, colorectal carcinoma, melanoma, and thyroid carcinoma. Given the rarity of these tumors, novel strategies and international collaborative efforts are necessary to advance research and improve outcomes.

Congenital Pulmonary Airway Malformations With a Reconsideration and Current Perspective on the Stocker Classification.

Congenital cystic pulmonary lesions (CCPLs) are represented by the following entities: congenital pulmonary airway malformation (CPAM), formerly congenital cystic adenomatoid malformation, extra- and intralobar sequestration (EIS), congenital lobar emphysema (overexpansion), and bronchogenic cyst. The developmental model of CPAM histogenesis by Stocker proposed perturbations designated as CPAM type 0 to type 4 without known or specific pathogenetic mechanisms along the airway from the bronchus to the alveolus. This review highlights mutational events either at the somatic level in KRAS (CPAM types 1 and possibly 3) or germline variants in congenital acinar dysplasia, formerly CPAM type 0, and pleuropulmonary blastoma (PPB), type I, formerly CPAM type 4. The potential for overt malignant progression exists in the case of PPB type I and CPAM type 1 in some cases to well-differentiated mucinous adenocarcinoma. On the other hand, CPAM type 2 is an acquired lesion resulting from interruption in lung development secondary to bronchial atresia. The latter is also regarded as the etiology of EIS whose pathologic features are similar, if not identical, to CPAM type 2. These observations have provided important insights into the pathogenetic mechanisms in the development of the CPAMs since the Stocker classification.

Pleuropulmonary blastoma type I presenting as a tension pneumothorax: a case report and review of the literature.

Pleuropulmonary blastoma (PPB) is a very rare, aggressive, embryonal pulmonary malignancy that mostly affects children under the age of 5 years. According to the histological features, three subtypes of PPB have been recognized: type I (purely cystic), type II (grossly visible cystic and solid elements), and type III (purely solid). The authors report a case of a 10-month-old male infant with type I PPB, who was clinically misdiagnosed with pneumothorax, that he presented complaining of shortening of breath, fever, and cough. Radiographs of the patient showed right pneumothorax, so he had managed accordingly in another centre without improvement. Then Computed Tomography showed a huge right upper lobe sepated pneumocyst, which was treated surgically and the diagnosis was confirmed by combining the imaging and the histopathological examination as PPB type I. PPB is a relatively rare tumour, and it is important to put PPB with their subtypes within the differential diagnoses of any pulmonary lesion in children below the age of 5 or 6 years, as the early diagnosis will help to give early management. Hence, the patient may have a better outcome.

Type II pleuropulmonary blastoma mistaken for rhabdomyosarcoma: A case report.

INTRODUCTION: Pleuropulmonary blastoma (PPB) is rare, representing 0.3 % of all pediatric cancers. PPB is classified into three subtypes and may progress from type I to types II and III, with a worse prognosis. Given its rarity, the diagnosis is frequently challenging. CASE PRESENTATION: We report an occurrence of PPB in a 3-year-old girl, who presented recurrent pneumopathy. Imaging investigations revealed a large solid lesion in the left hemithorax. Biopsy followed by histological analysis suggested rhabdomyosarcoma. The patient received neoadjuvant chemotherapy before proceeding to complete tumor excision. Surgical exploration revealed that the tumor was primitively related to parietal pleura and lower lobe of left lung. Histopathology of the tumor retained a definitive diagnosis of PPB type II. Postoperative course was uneventful, and a cerebral MRI ruled out brain metastasis. Adjuvant chemotherapy was administered. DISCUSSION: Clinical expression of PPB is nonspecific and variable. It ranges from a dry cough to respiratory distress. Standard radiography is the first examination to perform and CT is the gold standard for characterization thoracic masses. Surgery and chemotherapy are the pillars of treatment. Indications depend on the tumor type, its extent and its resectability. CONCLUSION: PPB is an aggressive tumor that occurs only in children. Due to the rarity of PPB, evidence on optimal treatment is still insufficient. Careful follow-up is necessary searching for local recurrence or metastasis.

Congenital pleuropulmonary blastoma in a newborn with a variant of uncertain significance in DICER1 evaluated by RNA-sequencing.

BACKGROUND: Pleuropulmonary blastoma (PPB) is a rare mesenchymal malignancy of the lung and is the most common pulmonary malignancy in infants and children. Cystic PPB, the earliest form of PPB occurring from birth to approximately two years of age, is often mistaken for a congenital pulmonary airway malformation, as the two entities can be difficult to distinguish on imaging and pathology. Diagnosis of PPB should prompt workup for DICER1 syndrome, an autosomal dominant tumor predisposition syndrome. We report a newborn with a congenital PPB presenting with tachypnea and hypoxia, who was found to have variant of uncertain clinical significance (VUS) in DICER1. CASE PRESENTATION: A term female infant developed respiratory distress shortly after birth. Initial imaging was concerning for a congenital pulmonary airway malformation versus congenital diaphragmatic hernia, and she was transferred to a quaternary neonatal intensive care unit for management and workup. Chest CT angiography demonstrated a macrocytic multicystic lesion within the right lower lobe without systemic arterial supply. The pediatric surgery team was consulted, and the neonate underwent right lower lobectomy. Pathology revealed a type I PPB. Oncology and genetics consultants recommended observation without chemotherapy and single gene sequencing of DICER1, which identified a germline VUS in DICER1 predicted to alter splicing. RNA-sequencing from blood demonstrated that the variant resulted in an in-frame deletion of 29 amino acids in a majority of transcripts from the affected allele. Due to the patient's young age at presentation and high clinical suspicion for DICER1 syndrome, tumor surveillance was initiated. Renal and pelvic ultrasonography were unremarkable. CONCLUSION: We present the case of a term neonate with respiratory distress and cystic lung mass, found to have a type I PPB with a germline VUS in DICER1 that likely increased her risk of DICER1-related tumors. Nearly 70% of patients with PPB demonstrate germline mutations in DICER1. Review of RNA sequencing data demonstrates the difficulty in classifying splice variants such as this. Penetrance is low, and many patients with pathogenic DICER1 variants do not develop a malignancy. Best practice surgical and oncologic recommendations include an individualized approach and tumor board discussion. This case highlights the importance of a multidisciplinary team approach and the utility of international registries for patients with rare diagnoses.