[size=20px]A previously healthy six month male infant presents with cough and fever. A chest radiograph reveals bronchiolitic changes and a large right lung cyst. After treatment, a follow up CXR 6 weeks later is normal except for a persistent cyst, and chest CT scan demonstrates a multilocular, 5 cm peripheral lung cyst in the right lower lobe, without air fluid levels or a feeding vessel. Prenatal ultrasounds were normal.

 

The next step in the care of this child should be:

 

A Bronchoscopy

 

B Sweat test to exclude cystic fibrosis

 

C Thoracoscopic or open right lower lobectomy

 

D B-Catenin gene analysis

 

E Repeat CXR in 3 months[/size]

E

think again my dear

C

It could be CPAM , early intervention will be a key to avoid future infection and complication

C

It could be CPAM , early intervention will be a key to avoid future infection and complication

correct

 

The management of coincidentally discovered cystic lung lesions in infancy is challenged by the similarity in radiographic appearance between congenital pulmonary airway malformations (CPAM) with cystic morphology (notably Types 1 and 4), necrotizing pneumonia with pneumatocele or lung abscess formation and rare cystic lung tumors, most notably pleuropulmonary blastoma (PPB) Type 1. In the clinical scenario presented above, it is assumed that the pulmonary symptoms are due to a viral infection, and that the asymptomatic cystic lung lesion is either a CPAM or PPB.

 

The clinical differentiation of these two entities can be difficult. Type 4 CPAM can be confused with PPB and may appear similar on cross-sectional imaging. A recent paper by Feinberg et al sought to compare clinical and radiographic features of histologically confirmed cases of CPAM and PPB and found that the following factors predicted a diagnosis of CPAM: prenatal detection, absence of symptoms, absence of pneumothorax, presence of a feeding vessel and simple (vs complex) cyst. Despite case reports of suspected malignant degeneration of CPAMs into sarcomas or other tumor types, the hypothesis that a CPAM can transform into a PPB has been refuted by genetic and immunohistochemical analyses which suggest that these are completely unrelated disease entities.

 

PPBs undergo a progression through cystic and then solid morphology, which permits a classification system which roughly correlates to age at detection and prognosis. Type I PPB is purely cystic and appears as multiloculated air-filled cysts which present with symptoms at a median age of 8 months. Undetected type I PPBs can progress to become Type II (solid and cystic) with presentation at a median age of 35 months. The most advanced stage PPB is Type III which is purely solid, is not seen before 12 months, and has a median age at diagnosis of 41 months. The distribution of PPBs according to timing of detection is approximately one third in the first 8 months, 60% in the first year with 97% of tumors being detected within the first 3 years of life. Survival rates are greater than 80% for type I PPB, but drop to about 40% for types II and III PPB, which obviously supports treatment of PPB at the earliest possible stage.

 

Germline loss of function mutations in DICER1 have been identified in 70-80% of children with PPB, with nearly all remaining patients exhibiting somatic mutations. The occurrence of PPB without DICER1 is felt to be rare. The role of DICER1 screening in children with lung cysts remains somewhat controversial. However, the PPB Registry and other experts strongly recommend screening of all patients with suspected CPAM who are being considered for non-operative management.