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Pleuropulmonary blastoma (PPB) is a rare, aggressive, primary intrathoracic malignancy of mesenchymal origin that arises from the lung parenchyma, pleura, or both, almost exclusively in infants and young children. It is part of the DICER1 syndrome tumor spectrum.

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Most common primary childhood lung tumor

Epidemiology

Age: Almost exclusively seen in children <6 years
Peak incidence: ~2–4 years
Slight male predominance
Accounts for ~0.5% of pediatric lung tumors
Often associated with germline mutations in the DICER1 gene

Classification

Type	Typical Age	Description	Imaging Appearance
Type I	<1 year	Purely cystic, benign-appearing	Multiloculated air- or fluid-filled cysts
Type II	~2–3 years	Mixed cystic and solid	Thick-walled cysts with solid nodules
Type III	>3 years	Purely solid, highly aggressive	Large solid mass, possibly necrotic

Type I can progress to Type II or III if untreated.
Type Ir (regressed): Non-progressive cystic variant.

Clinical Presentation

Respiratory distress, cough, fever
Recurrent pneumothorax (especially in Type I)
Chest pain or mass on palpation
May mimic pneumonia, congenital cysts, or CPAM