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.
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.
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.
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.
Not good imaging modality of choice. Non specific and may shows a large region of consolidation without sonographic air bronchograms 3.
Treatment and prognosis
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:
- intrathoracic soft tissue sarcoma
- PNET of thorax
- large bronchogenic cyst/lung cyst (for type I)
- FLIT (fetal lung interstitial tumour)10
- types 1 and 4 CPAM's: for type 1 PPB
lung cancer: overview
non small-cell lung cancer
- adenosquamous carcinoma
- large cell carcinoma
- primary sarcomatoid carcinoma of lung
- squamous cell carcinoma
- salivary gland type tumours
- pulmonary neuroendocrine tumours
- preinvasive lesions
- benign neoplasms
- pulmonary metastases
- lung cancer screening
- lung cancer staging
- non small-cell lung cancer
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