RESULTS
Sixteen children (ages 8d to 3y4m at first CT: 9M,7F) with subpleural
cysts were identified during the study period over 22 years. Of
these 16 children, 7 children received only a single CT examination. The
remaining 9 children underwent multiple CT studies (up to three
CTs in 4 children and four CTs in
1 child) at variable intervals depending on the clinical need. Of the 9
children who underwent repeat CT chest examinations, 7 occurred> 5 months after the first scan, and 6 children went
on to have a third CT after an average of 12 months. One child had a
fourth follow-up CT, performed 10 years after their initial CT.
Considering the known association with Trisomy 21, we divided the cases
into two groups based on their genetic profiles (Table 1). The first
group had an underlying genetic defect identified (n=11) while the
second group had no identifiable genetic defect (n=5).
Findings of the CT scans are provided in Table 2. Of note, only 2
children manifested unilateral cysts. In the first child (case 12),
cysts were only present on the left side. This child had left lower
pulmonary vein stenosis and a smaller left lung. In the second child,
(case 13), only right sided cysts were seen. This child had an absent
right pulmonary artery and a smaller right lung.
While Trisomy 21 was the most common underlying genetic association when
a genetic disorder was discovered (n=6/11), the cysts were found in
other rare disorders, including one case of Kabuki syndrome and one case
of Cornelia-de-Lange syndrome. The other 4 genetic abnormalities are
listed. The remaining 5 children listed had other clinical pathologies
which did not warrant genetic evaluation.
The most common clinical pathology in all these children was some form
of congenital heart disease (14/16), most associated with left to right
physiology (VSD or AVSD in 6/14, ASD in 6/11,
PDA in 2/11, allowing for
children with multiple defects). Pulmonary artery hypertension was
recorded to be present in 8 children.
Two children who had no defined genetic abnormality were discovered to
have these cysts in their teens, one with microscopic polyangiitis and
one with hepatoportal sclerosis at birth of unknown etiology requiring
liver transplantation (Image 2). Of note, this latter case had secondary
hepatopumonary syndrome before liver transplantation.
While only a small number of children underwent follow-up CT scans for
assorted reasons, it is noteworthy that in most cases (n=5/9) the number
and size of cysts increased with time. (Image 1). The child with
hypoplastic left heart syndrome (case 12) had 2 CTs performed in the
first year of life that had no peripheral cysts, with the cysts only
appearing on the 3rd CT at 2 years of age.
We could not find any significant correlation with ventilatory
requirements. 7 cases required mechanical ventilation, usually in
association with surgery for the underlying CHD. All 7 cases had
underlying CHD, of which 5 were premature as well.
Pulmonary function tests were only performed in 2 teens, with
contradictory results.
Indications for CT chest examination included evaluation of lung
parenchyma in moderate to severe PAH (6/16), pre-operative evaluation of
an underlying congenital heart disease (2/16), post-operative follow-up
for worsening hypoxemia (2/16), and evaluation of recurrent upper
respiratory tract infections (3/16). Other indications included
evaluation of antenatally diagnosed pulmonary lymphangiectasia (1/16),
concern for right-to-left shunting (1/16), and evaluation of
non-specific dry cough and respiratory difficulty (1/16).
Histopathology was correlative in only two cases, both with Trisomy 21.
The first was performed at the time of cardiac surgery (case 1) which
demonstrated focal enlargement and simplification of subpleural alveolar
spaces (image 3). The second was at autopsy (case 9) A third biopsy was
performed in the teen with ANCA (Anti Neutrophil Cytoplasmic Antibodies)
positive MPO positive microscopic polyangiitis, revealing pulmonary
hemosiderosis without capillaritis.
Long term outcomes seemed to be
more related to the child’s underlying anomalies than to a pulmonary
etiology. All 5 children who died had underlying CHD. Short term
outcomes could not be associated with the presence of subpleural cysts
due to the paucity of cases and to the complexity of confounding
clinical variables including but not limited to prematurity, CHD,
surgeries and intercurrent infections.