# Pleuropulmonary Blastoma in Children: A Nationwide Multicenter Study

## TL;DR

This study examines the treatment and outcomes of pleuropulmonary blastoma in 15 children, highlighting the importance of surgery and chemotherapy.

## Contribution

The study provides a nationwide multicenter analysis of PPB in children, emphasizing clinical and genetic findings.

## Key findings

- PPB is often diagnosed in children under 4 years old and is associated with CNS relapse despite treatment.
- Complete surgical resection is a key prognostic factor for better outcomes in PPB patients.

## Abstract

The aim of the study was to analyze the treatment of pleuropulmonary blastoma (PPB) in a group of 15 pediatric patients, with a median age of 39 months. PPB is a primary, malignant tumor of the lung and pleura in populations of young children. Key elements of treatment include surgical resection and postoperative chemotherapy. Regional and distant metastases have been reported in 20% of patients at diagnosis. Progressive and relapsed disease was observed, all with CNS involvement with a very poor outcome. The clinical manifestation of PPB is nonspecific, and the tumor can be misdiagnosed with congenital lung malformation. Genetic testing towards DICER1 pathogenic variants is recommended to recognize PPB and other DICER1-associated disorders.

Background/Objectives: This study involved an analysis of clinical data, histological types, genetic predisposition, treatment and outcomes in PPB in children. Patients and methods: We conducted a retrospective review of children treated for PPB at Polish pediatric oncology centers between 2011 and 2024. Results: A total of fifteen children (seven boys, eight girls; median age of 39 months; range: 27–64 months) were included. Type II solid/cystic PPB and type III solid PPB were diagnosed in six and eight children, respectively (one not known). Overall, 93% of patients were diagnosed at up to 4 years of age. Metastatic disease at diagnosis was confirmed in three (20%) patients, localized in bones, bone marrow and lymph nodes. Diagnosis was confirmed via central pathology review in 11 patients (73%). DICER1 pathogenic variants were identified in eight patients. All children presented with respiratory symptoms. The tumor dimensions were >10 cm (n = 7), 5–10 cm (n = 5) and <5 cm (n = 2). No bilateral lung involvement was observed. Tumor biopsy was performed in six children (40%), with subsequent resection (R0) in five patients. Primary resection (R0) was achieved in three patients (20%) with type II (n = 1) or type III (n = 2). In the other six patients, non-radical resection was performed: R1 in four (27%) children (with a tumor rupture in one patient) and R2 (subtotal resection) in two children (13%). All patients received postoperative chemotherapy. Maintenance chemotherapy was given to two patients. No patient received radiotherapy as first-line treatment. Progressive disease occurred in two patients in the CNS and lungs. Relapsed disease appeared in three patients, all with CNS involvement. Conclusions: PPB is a rare, malignant tumor of early childhood with an uncertain prognosis. Despite multimodal treatment, patients remain at risk of progression or CNS relapse. Complete surgical resection remains a key prognostic factor.