Pulmonary interstitial emphysema in adults: a clinicopathologic study of 53 lung explants.

Pulmonary interstitial emphysema (PIE) is an unusual condition wherein air dissects through alveolar walls into the adjacent interstitial tissues where it forms cystic spaces with an associated inflammatory reaction. It is well described in premature infants with respiratory distress syndrome and is observed in adults, usually in association with ventilator use. The fibrotic and inflammatory appearance may mimic normal anatomic structures as well as pathologic changes such as granulomatous disease, organizing pneumonia, fibroblast foci of usual interstitial pneumonia, or lymphangiectasia. The presence of interstitial emphysema has not been well characterized in the adult population. We retrospectively reviewed 53 consecutive explanted lungs for the histologic presence of PIE, of which 19 (36%) cases were found to be positive. PIE was seen most commonly in patients with usual interstitial pneumonia. Review of the medical record for each patient revealed no correlation between the presence of PIE and duration of disease. A correlation was seen between prior ventilation and/or biopsy. These findings may indicate that PIE is a result of medical intervention; however, in the remainder of cases the disease process itself may have been a contributing factor.