Pleuropulmonary Blastoma Deep Research Notes

Date: 2026-04-12 Curator: Codex manual synthesis

Scope

Disease: Pleuropulmonary blastoma (PPB)

Primary disease anchor: - MONDO:0011014 pleuropulmonary blastoma

Cancer-modeling choices applied from dismech issue #1198: - The dismech page is the disease-level mechanism graph for PPB, not a page per ontology child. - disease_term stays MONDO-first. - NCIT is added at disease mapping level and subtype mapping level for oncology grounding. - Type I, Type Ir, Type II, and Type III are modeled as flat histological subtype facets inside one PPB entry. - Type Ir is not split into its own disease file; it shares the same causal program and is represented as a subtype facet with NCIT grounding. - No subtype is intended to imply a separate local page or "Not Yet Curated" debt. - NCIT was preferred over MAXO only where it provided materially better oncology specificity, such as disease/subtype mapping and complete resection. - MAXO remained appropriate for generic chemotherapy and radiation actions because NCIT did not provide an exact IVADo regimen term.

Core Disease Summary

PPB is a rare pediatric intrathoracic mesenchymal malignancy that progresses along a cystic-to-solid continuum.

Key disease-defining points: - Registry-scale natural history: PMID:25209242 - "Pleuropulmonary blastoma (PPB) has 3 subtypes on a tumor progression pathway ranging from type I (cystic) to type II (cystic/solid) and type III (completely solid)." - "A germline mutation in DICER1 is the genetic cause in the majority of PPB cases." - Familial predisposition discovery: PMID:19556464 - "Here, we show that 11 multiplex PPB families harbor heterozygous germline mutations in DICER1..." - Progressive tumor genomics: PMID:24909177 - PPB cysts can "progress to high-grade sarcoma." - Tumors show compound DICER1 disruption plus frequent TP53 loss and occasional NRAS/BRAF mutation.

Subtype Axis

Histologic subtype facet retained inside the single PPB entry: - Type I - Purely cystic lesion with primitive small cells. - MONDO:0020555 - NCIT:C45626 - Type Ir - Purely cystic lesion lacking primitive small cells. - No MONDO subtype located during curation. - NCIT:C211861 - Type II - Mixed cystic and solid PPB. - MONDO:0020556 - NCIT:C45627 - Type III - Purely solid PPB. - MONDO:0020557 - NCIT:C45628

Supporting subtype evidence: - PMID:36541021 - "Type I PPB is a purely cystic lesion that has a microscopic population of primitive small cells with or without rhabdomyoblastic features and may progress to type II or III PPB, whereas type Ir lacks primitive small cells." - PMID:25209242 - "Thirty-three percent of the 350 PPB cases were type I or type I regressed (type Ir), 35% were type II, and 32% were type III or type II/III." - "The median ages at diagnosis for type I, type II, and type III patients were 8, 35, and 41 months, respectively."

Pathology and Natural History

Type I pathology: - PMID:18223332 - "Type I PPB is a delicate multilocular cyst with variable numbers of primitive mesenchymal cells beneath a benign epithelial surface." - "Rhabdomyoblasts and cartilage nodules are seen in 49% and 40% of cases, respectively." - "recognition of this lesion as a neoplasm with malignant potential rather than a developmental cystic malformation is vital..."

Progression and prognosis: - PMID:25209242 - "The 5-year overall survival (OS) rate for type I/Ir patients was 91%; all deaths in this group were due to progression to type II or III." - "Metastatic disease at the diagnosis of types II and III was also an independent unfavorable prognostic factor." - PMID:36541021 - "For young children with type I PPB, outcomes are favorable, but complete resection is indicated because of the risk for progression."

Mechanism Synthesis

Atomic mechanism chain used in the YAML:

Germline DICER1 predisposition
PMID:19556464
Heterozygous germline DICER1 mutations define familial PPB predisposition.
Compound DICER1 disruption
PMID:24909177
Loss-of-function DICER1 allele plus somatic RNase IIIb missense mutation.
Aberrant 5p miRNA processing
PMID:24909177
"5p-Derived microRNA (miRNA) transcripts retained abnormal precursor miRNA loop sequences normally removed by DICER1."
Epithelial FGF9 overexpression
PMID:25978641
"FGF9 is overexpressed in lung epithelium in the initial multicystic stage of Type I PPB..."
Pulmonary mesenchymal hyperplasia
PMID:25978641
Increased epithelial Fgf9 in mice "results in pulmonary mesenchymal hyperplasia and a multicystic architecture..."
TP53 loss
PMID:24909177
Frequent biallelic TP53 loss is a recurrent cooperating lesion in progressive PPB.
RAS pathway activation
PMID:24909177
NRAS or BRAF mutation occurs in some cases.
Sarcomatous progression
PMID:24909177
PPB cysts can progress to high-grade sarcoma.
PMID:25209242
Clinical registry data ties progression to worse survival.

Mechanistic interpretation: - The key upstream distinction is between predisposition and lesion-level transformation. - DICER1 is not modeled as a single bundled node; predisposition, second-hit disruption, miRNA processing failure, epithelial FGF9 dysregulation, and mesenchymal hyperplasia are split into separate causal steps. - TP53 loss and RAS-pathway mutation are treated as additional cooperating progression lesions rather than as alternative root causes.

Clinical Presentation

Useful phenotype-supporting references: - PMID:16410110 - "PPB must be included in the differential diagnosis of a fetus, neonate, or child with a cystic lung mass." - PMID:37119756 - "Clinical expression of PPB is nonspecific and variable. It ranges from a dry cough to respiratory distress." - PMID:34345335 - Type II case abstract includes fever, nonproductive cough, and dyspnea. - PMID:32175165 - Type III cases "presenting with pneumothorax" support that phenotype as a real but uncommon presentation. - PMID:11002236 - "Respiratory distress was the most common clinical symptom."

Phenotype terms selected for YAML: - HP:0032445 Pulmonary cyst - HP:0012735 Cough - HP:0002094 Dyspnea - HP:0002098 Respiratory distress - HP:0002107 Pneumothorax

Treatment Evidence

Surgery: - PMID:33826235 - "Complete tumor resection is a main prognostic factor..." - PMID:36541021 - Complete resection is indicated even in type I disease because of progression risk.

Chemotherapy: - PMID:36137255 - "Beginning in 2007, the IVADo regimen (ifosfamide, vincristine, actinomycin-D, and doxorubicin) was recommended..." - "Adjusted analyses suggest improved overall survival for children treated with IVADo..."

Radiotherapy: - PMID:33826235 - Chemotherapy and "in some cases radiotherapy" are included in multimodal treatment.

Modeling note: - Exact NCIT regimen grounding for full IVADo was not available from the queried ontology results. - The treatment entry therefore uses MAXO chemotherapy plus CHEBI agents rather than an inexact NCIT regimen approximation.

Ontology Grounding Used

Disease and subtype grounding: - MONDO:0011014 pleuropulmonary blastoma - NCIT:C5669 Pleuropulmonary Blastoma - MONDO:0020555 pleuropulmonary blastoma type 1 - MONDO:0020556 pleuropulmonary blastoma type 2 - MONDO:0020557 pleuropulmonary blastoma type 3 - NCIT:C45626 Type I Pleuropulmonary Blastoma - NCIT:C211861 Type Ir Pleuropulmonary Blastoma - NCIT:C45627 Type II Pleuropulmonary Blastoma - NCIT:C45628 Type III Pleuropulmonary Blastoma

Representative histopathology terms: - NCIT:C155651 Primitive Mesenchymal Stroma Formation - NCIT:C35937 Rhabdomyosarcomatous Differentiation - NCIT:C9118 Sarcoma

Representative biological process terms: - GO:0035196 miRNA processing - GO:0035195 miRNA-mediated post-transcriptional gene silencing - GO:0008543 fibroblast growth factor receptor signaling pathway - GO:0010463 mesenchymal cell proliferation - GO:0030324 lung development

Representative anatomy and cell terms: - CL:0000082 epithelial cell of lung - CL:0008019 mesenchymal cell - UBERON:0000115 lung epithelium - UBERON:0004883 lung mesenchyme - UBERON:0002048 lung

Representative gene terms: - hgnc:17098 DICER1 - hgnc:3687 FGF9 - hgnc:11998 TP53 - hgnc:7989 NRAS - hgnc:1097 BRAF