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

Abstract

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 follow-up: 5 (5.5%) T-I, 1 (4%) T-Ir. Progression to high-grade Type II or III occurred in 9/91 (10%) T-I and 2/25 (8%) T-Ir. The addition of chemotherapy did not significantly reduce progressions (Fisher’s exact test). All of the tumor progressions were seen by 75 months of age; this finding is similar to broader IPPBR data: > 95% of patients are diagnosed with Type II/III by 72 months of age. Of the 9 patients with T-I who progressed, 5 ultimately died, whereas the 2 T-Ir who progressed were alive. At last follow-up 111/116 (95.6%) were alive. Conclusions: A cyst in an older individual most likely will be Type Ir. Type I and Type Ir are clinically similar with a small risk of progression to the advanced Type II/III up to 6 years of age. Outcome for those whose cystic PPBs progressed is poor. The role of chemotherapy remains uncertain for the prevention of progression in the pure cystic PPB Type I or Ir. [Table: see text]