Pleuropulmonary blastoma

A 4-year-old boy presented at the emergency department with fluctuating fever. The child's father noticed shortened breathing and fatigue lasting approximately one month. The patient suffered from activity-related tachycardia and tachypnoea. The clinical examination showed right-sided cardiac auscultation and diminished left-sided breath sounds

Chest radiograph showed almost complete opacification of the left lung with right-sided cardiomediastinal shift and a lucent well-defined lesion in the right lower lobe medially and posteroinferiorly (Figure 1). Subsequent ultrasound demonstrated solid lesion in the left hemithorax with adjacent pleural fluid (Figure 2). Contrast-enhanced computer tomography (CT) of the chest showed a large solid heterogeneously enhancing intrathoracic mass on the left side with right-sided cardiomediastinal displacement. There was accompanying left-sided pleural effusion and partial atelectasis of the left upper lobe (Figure 3 and 4). In the right lower lobe, a cystic lesion with thin intralesional septations was seen (Figure 4).

Biopsy via minithoracotomy and histopathological examination established the diagnosis of pleuropulmonary blastoma (PPB) type II. The cystic lesion in the right lung was diagnosed as congenital pulmonary airway malformation (CPAM). Molecular analysis proved associated DICER 1 gene mutation. The patient underwent adjuvant chemotherapy and left lower lobe lobectomy.

PPB is a rare primary lung malignancy affecting infants and children under 6 years of age. It is an aggressive, dysontogenetic, intrathoracic mesenchymal tumour occurring more commonly on the right-side [1,2].

There are 4 types PPB: purely cystic tumor either delineated (type 1) or not delineated by immature cancerous cells (type 1r; r stands for regressed), mixed cystic and solid (type 2), purely solid (type 3). Type 1 can progress to type 2 and 3. Only 8% type 1r tumors show onward progression to type 2 or 3 [1,2,3]. 

Clinical manifestations are nonspecific and may include chest or upper abdominal pain and general symptoms including anorexia and malaise [2].

PPB may be associated with genetic mutations, including DICER1 germline mutation and other extrapulmonary neoplasms [1,2,4].

PPB occurs in familial settings. Therefore the first and second-degree relatives should undergo genetic and imaging screening [1,2,4].

Chest radiograph typically demonstrates opacification of the hemithorax with associated mass effect. Ultrasound of chest shows consolidation with or without pleural fluid. CT imaging is used to diagnose PPB, evaluate the extent of the disease and monitor treatment.

 CT imaging typically demonstrates a single or multicystic air-filled mass (type 1), mixed solid- cystic mass with air- or fluid-filled cavities and air-fluid levels (type 2), homogeneously or heterogeneously enhancing low attenuating solid mass, which may show increased 18F-fluorodeoxyglucose uptake on PET-CT examination (type 3). MRI shows a heterogeneous mass with or without cysts, vascularized foci, intralesional haemorrhage and areas of restricted diffusion. The complications of PPB consist of pneumothorax, pleural and pericardial effusion [1].

Biopsy and subsequent histopathological examination is needed to establish a final diagnosis.

There is a variety of cystic lung lesions which may resemble PPB on imaging. Therefore, correlation with clinical history and histopathology is needed (see differential diagnosis list).

The primary treatment of PPB is surgical resection (type 1/1r, 2, 3) or adjuvant chemotherapy (CHT) to reduce the size of tumour followed by surgical excision (type 1,2,3). For recurrent tumours high dose CHT with autologous stem cell transplantation is recommended. Radiation therapy is reserved for nonresectable tumours or residual tumours after CHT [2,3].

Type 1 has a better prognosis than type 2 and 3. The event-free survival rate is 49% for all patients with PPB (83% for type 1, 49% for type 2, and 42% for type 3). Type 2 and 3 can metastasize in the skeletal and central nervous system [1,2].

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