Congenital Segmental Emphysema: An Evolving Lesion

Abstract

Congenital segmental emphysema (CSE) is a newly-recognised sub-type of congenital parenchymal lung anomaly. It is characterised by antenatal detection and post-natal evolution from an initially solid segmental appearance to a hyperlucent and hyperinflated segment. A retrospective review of a single-centre tertiary referral database between Jan 1994 and Dec 2007 was performed. 130 infants had antenatally detected lung anomalies, and of these 12 (9.2%) infants (initially labelled as congenital cystic adenomatoid malformation (CCAM)), showed features better defined as CSE. The lesions were described antenatally as non-progressive microcystic (n=6), hyperechogenic (n=2) or both (n=2). Early post-natal CT scans showed areas of solid segmental parenchyma, initial hyperlucency or microcysts. Subsequent CT imaging, however, showed evolution to segmental hyperlucency in areas previously solid and in 2 cases a central bronchocele was noted. Ten children underwent resectional surgery (segmentectomy n=4, lobectomy n=6) at a median age of 1 (range 0.4-5.2) year and the gross appearance of the resected specimen confirmed hyperinflated (not cystic) segments. Histological review showed localised abnormally dilated alveolar spaces in 7 cases. Adjacent areas consistent with type 2 CCAM were also seen (n=3). CSE lies within the spectrum of both CCAM and sequestration but there is a definite post-natal evolution and volume change which presage symptoms. This may be associated with segmental bronchial atresia and progressive air trapping via collateral airways such as the interalveolar pores of Kohn.