[size=6]A newborn infant with normal prenatal imaging is transferred to your NICU with a left-sided pneumothorax. The infant is slightly tachypneic but otherwise stable; receiving 0.5 LPM of supplemental oxygen for oxygen saturations greater than 95%. CT imaging identifies a single large (6cm), subpleural cyst in the basilar segment of the left lower lobe associated with a small pneumothorax. They undergo resection of the left lower lobe and a type 1 pleuropulmonary blastoma (PPB) is diagnosed after pathological analysis of the resected specimen. Which of the following necessitates the consideration of adjuvant chemotherapy in this patient?

 

a Cyst diameter greater than 5cm

 

b Multifocal cystic disease

 

c Younger age

 

d Pre-operative pneumothorax[/size]

c

A

D

D

correct answer

b Multifocal cystic disease

 

Pleuropulmonary blastoma (PPB) is the most common primary malignant lung tumor in children. It is classified into three types: Type 1 – purely cystic; Type 2 – mixed solid/cystic; and Type 3 – solid lesions. Type 1 is further subdivided into type 1r in which there is “regression” of the primitive malignant component within the cystic lesion. It is well known that there is progression of disease from Type 1 to Type 2 to Type 3. The diagnosis of PPB should prompt genetic testing since over 70% of PPB demonstrate DICER-1 germline mutations, the presence of which increases the risk for future malignancies.

 

While adjuvant chemotherapy has usually been reserved for PPB type 2 and 3 (Messinger, 2015), a recent analysis from the PPB International registry has identified a subset of type 1 patients who may also benefit. In their analysis of 244 centrally reviewed cases of PPB type 1 and type 1r, patients with multifocal disease or those who underwent less than R0 resections were more likely to recur or progress. Adjuvant chemotherapy appeared to have a protective effect for patient’s vs patients undergoing surgery alone. Progression was also more prevalent in cases undergoing surveillance alone, underscoring the importance of surveillance imaging, particularly post-operatively, when additional lesions may become more apparent. It is important to note that progression of type 1 lesions is generally uncommon as these patients have 5-year overall and event-free survival rates of 98% and 96.4%, respectively.