Outcome of 116 cases of pleuropulmonary blastoma type I and type Ir (regressed): A report from the International PPB Registry (IPPBR).

9522 Background: Pleuropulmonary blastoma (PPB) is a rare dysembryonic lung neoplasm of early childhood with progression from a purely cystic Type I (T-I) lesion to cystic solid and solid high grade sarcoma (Type II and Type III). A regressed form of PPB (T-Ir) has been recognized pathologically. The outcome of both T-I and T-Ir has been only partially described. Methods: Retrospective analysis of 345 IPPBR cases showed 116 T-I or T-Ir. In all cases the PPB diagnosis was made on surgically removed cysts. The treating physician decided whether to use chemotherapy after surgery. Results: The pathologic diagnosis of the 91 PPB T-I and 25 T-Ir is now confirmed by central review (LPD and DAH). Patients with T-I were younger than T-Ir (median: 8 months vs. 48 months).Diagnosis after age 6 years included only one T-I compared to 10 T-Ir patients. Therapy is not known for 28 T-I and 2 T-Ir. Surgery was followed by chemotherapy in 31 T-I and 2 T-Ir. Six (5%) recurred with the same type, all were alive at last foll...