Background/Purpose: Pleuropulmonary blastoma (PPB) is a rare primary neoplasm of pleuropulmonary mesenchyme. Fewer than 170 children have been reported, and few single institutions have reported more than several cases. Treatment for this condition is primarily surgical resection; however, increasing experience suggests that adjuvant chemotherapy may decrease recurrence and improve outcome. Methods: We reviewed the charts of all children with PPB treated at our institution since 1960. We reviewed the prenatal features, clinical presentation, operation, pathological findings, adjuvant treatment, and outcome. Results: Ten children (6 boys and 4 girls) were treated for PPB a t a mean age of 3.2 ±4.3 years. In 2, a cystic lung mass was diagnosed prenatally, and in 8, a cystic or solid and cystic lung mass was diagnosed postnatally (right lung, 3; left lung, 4; and bilateral, 3). In no patient was PPB considered preoperatively. Surgical resection was performed at 1 day to 11 years (median, 23 months) of age. Seven children had complete resection; 1 had microscopic residual disease, and 2 had gross residual disease. Pathology showed type I PPB in 7, type II in 1, and type III in 2. Five patients received adjuvant chemotherapy with vincristine, actinomycin, and cyclophosphamide-based regimens. At follow- up (mean, 7.7 ±11.5 years; range, 1-456 months), children with type I PPB have no evidence of disease (n = 6) or are lost to follow-up (n = 1), whereas all those with type II/III PPB have died of the disease. Conclusions: PPB must be included in the differential diagnosis of a fetus, neonate, or child with a cystic lung mass. This finding supports early resection of these lesions rather than observation or treatment with nonoperative strategies. Background / Purpose: Pleuropulmonary blastoma (PPB) is a rare primary neoplasm of pleuropulmonary mesenchyme. Fewer than 170 children have been reported, and few single institutions have reported more than several cases. suggests that adjuvant chemotherapy may decrease recurrence and improve outcome. Methods: We reviewed the charts of all children with PPB treated at our institution since 1960. We reviewed the prenatal features, clinical presentation, operation, pathological findings, adjuvant treatment, and outcome. : 12 children (6 boys and 4 girls) were treated for PPB ata mean age of 3.2 ± 4.3 years. In 2, a cystic lung mass was diagnosed prenatally, and in 8, a cystic or solid and cystic lung mass was diagnosed postnatally ( left lung, 4; and bilateral, 3). In no patient was PPB considered preoperatively. Surgical resection was performed from 1 day to 11 years (median, Seven had had resection; 1 had microscopic residual disease, and 2 had gross residual disease. Pathology showed type I PPB in 7, type II in 1, and type III in 2. Five patients received adjuvant chemotherapy with At follow-up (mean, 7.7 ± 11.5 years; range, 1-456 months), children with type I PPB have no evidence of disease (n = 6) or are lost to follow -up (n = 1), all all with type II / III PPB have died of the disease. Conclusions: PPB must be included in the differential diagnosis of a fetus, neonate, or child with a cystic lung mass. early resection of these lesions rather than observation or treatment with nonoperative strategies.