Introduction
Interstitial lung diseases in the pediatric population are currently characterized using a contemporary combined clinical and pathological approach as proposed by Kurland et al, from the ChILD consortium. (1). Childhood interstitial lung diseases (chILD) are now recognised as distinct entities, owing to newly appreciated pathogeneses unique to the pediatric age group, particularly evident in younger children. Advances in the radiological, pathological and genetic bases in recent years have prompted distinction of specialized subgroups of diffuse lung diseases that present during infancy.
At the authors’ institution, we have recently noted a radiographic pattern on computerised tomography (CT) of the chest, characterized by a rim of small 1-4 mm subpleural cysts at the periphery of the lungs. (images 1,2). The cysts are frequently but not exclusively symmetric and diffuse. The most frequently described diagnostic entity associated with these small air-filled cysts is Trisomy 21. (2, 3, 4, 5, 6, 7). Pathological specimens in children with Trisomy 21 have demonstrated cystic dilatations of the subpleural alveoli that communicate with dilated alveolar ducts. (2,7). There are only occasional case reports describing their occurrence in other genetic abnormalities, including Trisomies 10 and 18, and Filamen A mutation (3,8,9, 10)
We have seen this CT pattern of subpleural cysts in children without Trisomy 21. These are either primary (without any major lung abnormality) or in association with a co-existing cardiovascular abnormality. Through this retrospective analysis, we present a wider population manifesting subpleural cysts. We propose that these subpleural cysts are associated with pulmonary histological dysmaturity or immaturity, similar to that proposed in children with Down’s syndrome (2). Though rare, there is currently limited literature regarding their further clinical associations and their evolution over time.