Adult Pulmonary Interstitial Emphysema: A Clinically and Pathologically Underdiagnosed Entity with Distinct Clinicopathologic Features
Saraswati Pokharel, Lynette M Sholl, Sara O Vargas. Brigham and Women's Hospital, Harvard Medical School, Boston, MA
Background: Pulmonary interstitial emphysema (PIE) is identified by the presence of air in the connective tissue of the peribronchovascular sheath, interlobular septa and visceral pleura. It is described in premature infants but is not well characterized in adults.
Design: Pathology reports were searched for the term “interstitial emphysema” in pulmonary wedge resection, lobectomy, and pneumonectomy specimens obtained from January 2005 to September 2012. For patients with documented PIE, clinicopathologic data were recorded and archived slides were reviewed.
Results: During the study period, 5 lung resection reports documented the presence of PIE, including 4 pneumonectomies for lung transplantation and one volume reduction wedge biopsy post-lung transplantation. All reports with a diagnosis of PIE had been reviewed by a pathologist with pediatric expertise, responsible for approximately 13% of an adult lung pathology service caseload. Patients (mean age 59 ± 7 yr) included 4 nonsmokers and 1 former smoker. One had a history of pneumothorax, and 4 had a history of positive-pressure ventilation, 1 of whom had Nissen fundoplication complicated by pneumomediastinum and subsequent rapidly progressive lung disease. In none of the patients was PIE suspected clinically. Slides from 4 patients were available for review. All demonstrated characteristic histologic features of PIE, including cystic air-filled spaces lined with histiocytes/synoviocyte-like cells and giant cells, predominantly along bronchovascular bundles and subpleural areas. Fibrous scar tissue surrounding the cysts showed abundant delicate collagen fibers with occasional myxoid foci, often associated with interspersed eosinophils. The extent of PIE ranged from mild/moderate (n=2) to extensive (n=2); when extensive, PIE was the dominant pathologic finding. Lymphatic channels were at least mildly dilated in all cases. Other pathologic features included cystic bronchiectasis (n=1, with cystic fibrosis) and honeycomb change (n=3).
Conclusions: PIE is found in adult lungs following positive-pressure ventilation, pneumothorax, and thoracic surgery. It is underrecognized clinically. In a subset of severe interstitial lung disease cases, it constitutes a major pathologic feature. Histologically, it shows not only the classically described cystic spaces, but also a peculiar and distinctive pattern of peri-cyst fibrosis. It may be underdiagnosed by pathologists with limited exposure to diseases more commonly appreciated in the pediatric population.
Monday, March 4, 2013 9:30 AM
Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 293, Monday Morning