The morphologic spectrum of infantile lobar emphysema: a study of 33 cases.

Abstract

Infantile lobar emphysema (ILE) is a relatively uncommon entity characterised by radiologic pulmonary lobar overinflation. The spectrum of underlying pathology in ILE has not been previously detailed. We have reviewed thirty-three cases of ILE accessioned to the Armed Forces Institute of Pathology, Washington D.C., since 1970. Seventeen (51.5%) presented in the first week of life, 27 (81.8%) presented within the first six months, and an additional six cases presented beyond six months including three beyond 18 months of age. Upper lobe involvement occurred in 96.9% cases and multiple lobes were involved in six cases. Nine infants had polyalveolar (hyperplastic) lobes determined on the basis of radial alveolar counts (RACs), while 21 were considered to be "classic ILE" since these showed lobar hyperexpansion without any other abnormality. RACs in infants with classic ILE remained fairly constant irrespective of age unlike a progressive increase seen in normal age-matched controls, suggesting a post-partum arrest of acinar development in ILE. Additional findings included serpiginous bronchioles resembling those seen in extralobar sequestration in two cases, bronchopulmonary dysplasia in two cases, and one case each showing "cystic alveoli" and peripheral subpleural cysts. ILE thus seems to be a composite of various pathologies resulting in a single clinical entity. We hypothesise that the timing of an inciting functional or anatomic bronchial obstruction during in-utero lung development determines morphologic variation in ILE.