Pleuropulmonary blastoma

Pleuropulmonary blastomas (PPB) are a rare, variably aggressive, childhood primary intrathoracic malignancy. In up to 25% of cases, the mass can be extrapulmonary with attachment to the parietal pleura

PPB is encountered in childhood, mostly in the first years of life (90% in those between 0-2 years old). 

PPBs are associated with type 4 CPAM.  

PPB is associated with PPB family tumour and dysplasia syndrome in 33% of cases. Many of these patients have a mutation of the DICER-1 gene. In 10% of cases, patients with PPB may also present with multilocular cystic nephroma, and, very rarely, Wilms tumour 7-9.

PPB comprises both mesenchymal and epithelial components resembling fetal lung. Bilateral occurrence is very rare.

This classification is a continuum from the less malignant to the most malignant lesion:

  • cystic: type 1 (prenatal and 10 months old), 14%
  • mixed: type 2 (mean age 34 months), 48%
  • solid: type 3 (mean age 44 months), 38%

Type 1 PPBs are impossible to differentiate from types 1 and 4 CPAM. Thus, it must be included in the differential diagnosis, particularly if the patient is known for another type of blastoma, as 25% of PPB appear in families with a history of blastomas.

PPBs are usually right-sided, pleural-based, without chest wall invasion and without calcifications. It can sometimes present with pneumothorax. Types 2 and 3 PPBs are associated with CNS and bone metastases.

Often late presentation at radiographic diagnosis. Unilateral lung whiteout on plain film with mediastinal shift to opposite side. Usually, there are no adjacent rib erosions or calcifications.

A poor imaging modality for this diagnosis. Non-specific and may show a large region of consolidation without sonographic air bronchograms 3.

Usually seen as a large mass in the thorax with mixed solid-cystic heterogeneous low attenuation, pleural effusion (not dominant abnomality), contralateral mediastinal shift, and lack of chest wall invasion 3,4.

  • type 1 lesions manifest as a single cyst or a multicystic lesion (often air filled)
  • type 2 lesions show air- or fluid-filled cavities with possible air-fluid levels along with solid internal nodules
  • type 3 neoplasms are solid lesions that show low attenuation at CT and homogeneous or heterogeneous enhancement

Type 3 PPB shows increased fluorodeoxyglucose (FDG) uptake at PET/CT 13

Type I tumours have a good prognosis. Complete surgical resection is often the treatment of choice, as it is with CPAM. Tumours larger than 5 cm just like type 1 and 2 PPB carry a worse prognosis 2.

The differential diagnosis for type 1 PPB includes other cystic lesions:

The differential diagnosis for type 2 and 3 PPB, particularly when they are locally aggressive, includes more common tumors 13:

Lung cancer
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Article information

rID: 7340
Tag: cases
Synonyms or Alternate Spellings:
  • Pulmonary blastoma
  • Pleuropulmonary blastomas
  • Pulmonary blastomas
  • Pleuropulmonary blastoma (PPB)
  • Pleuro-pulmonary blastoma
  • Pleuroparenchymatous blastoma
  • Pleuroparenchymatous blastomas
  • Pneuoblastoma lung
  • Pleuropulmonary blastomata

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