Programmed Death Ligand 1 Expression and Related Markers in Pleuropulmonary Blastoma

Zahra Alipour, Kris Ann P. Schultz, Ling Chen, Anne K. Harris, Ivan A. Gonzalez, John Pfeifer, D. Ashley Hill, Mai He, Louis P. Dehner

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


Introduction: Pleuropulmonary blastoma (PPB), a rare childhood neoplasm of the lung, is linked to pathogenic DICER1 variants. We investigated checkpoint inhibitor markers including Programmed Death Ligand 1 (PD-L1), PD1, CD8 and tumor mutational burden (TMB) in PPB. Material and Methods: Cases were collected from departmental archives and the International PPB/DICER1 Registry. Immunohistochemistry (IHC) for PD-L1, PD-1, CD8 and DNA mismatch repair (MMR) genes were performed. In addition, normal-tumor paired whole exome sequencing (WES) was performed in two cases. Results: Twenty-five PPB cases were studied, consisting of Type I (n = 8, including 2 Ir), Type II (n = 8) and Type III (n = 9). PD-L1 combined positive score (CPS) of 1, 4 and 80 was seen in three (3/25, 12.0%) cases of Type II PPB with negative staining in the remaining cases. PD-1 and CD8 stains demonstrated positive correlation (P <.05). The density of PD1 and CD8 in the interface area was higher than within tumor (P <.05). The MMR proteins were retained. TMB was 0.65 mutations/Mb in type II PPB with high expression of PD-L1, and 0.94 mutations/Mb in one negative PD-L1 case with metastatic tumor. Conclusion: A small subpopulation of PPB patient might benefit from checkpoint immunotherapy due to positive PD-L1 staining.

Original languageEnglish
Pages (from-to)523-530
Number of pages8
JournalPediatric and Developmental Pathology
Issue number6
StatePublished - Nov 2021


  • DNA mismatch repair
  • PD-1
  • PD-L1
  • pleuropulmonary blastoma
  • tumor mutation burden
  • whole exome sequencing


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