Pleuropulmonary blastoma

Pleuropulmonary blastomas (PPB) are 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). 

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

Classification

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

  • cystic: type I (prenatal and 10 months old), 14%
  • mixed: type II (mean age 34 months), 48%
  • solid: type III (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 history of blastomas.

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

Associations

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, patient with PPB may also present with multilocular cystic nephroma, and, very rarely, Wilms tumour 7-9.

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

CT

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

Ultrasoound

Not good imaging modality of choice. Non specific and may shows a large region of consolidation without sonographic air bronchograms 3.

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

General imaging differential considerations include:


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Article Information

rID: 7340
Systems: Chest, Paediatrics
Section: Pathology
Tag: cases
Synonyms or Alternate Spellings:
  • Pulmonary blastoma
  • Pleuropulmonary blastomas
  • Pulmonary blastomas
  • Pleuropulmonary blastoma (PPB)
  • Pleuro-pulmonary blastoma
  • Pleuroparenchymatous blastoma
  • Pleuroparenchymatous blastomas
  • Pneuoblastoma lung

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