[1872] Pulmonary Interstitial Emphysema in Adults: A Potential Diagnostic Pitfall

Sara M Barcia, Kirk D Jones. University of California San Francisco, San Francisco, CA

Background: Pulmonary interstitial emphysema (PIE) is well described in premature infants with respiratory distress syndrome and is observed in adults, usually in association with ventilator use. In this condition, air gains access to the lung interstitium via rupture of small alveoli and bronchioles, then dissects through interstitial connective tissue along lymphatic routes. Chronically, angular cystic spaces form, lined by foreign body giant cells and fibrosis. The fibroinflammatory reaction around cyst-like spaces may mimic fibroblast foci and honeycombing, infectious granulomas, or lymphangiectasia, resulting in erroneous diagnoses or unnecessary additional workup. In this study, we investigated the frequency of PIE in explanted lungs and correlate the findings with clinicopathologic diagnoses, ventilator status and duration of disease.
Design: We identified 53 patients who underwent lung transplant at our institution between February 2010 and June 2011. Each case was reviewed by a specialist in pulmonary pathology for the presence of PIE. The electronic medical record was reviewed to identify clinical diagnoses, ventilator status, duration of disease and history of prior biopsy.
Results: 19 of 53 (36%) cases were identified with PIE. Interstitial air reaction was observed in several different diseases. No association was seen between PIE and ventilator status, history of prior surgical biopsy or duration of disease. Histologic features of PIE included elongated or angulated spaces, most commonly around bronchovascular bundles. The cyst-like spaces were lined by scant to prominent foreign body giant cells with macrophages, and surrounded by variable fibrosis and eosinophils. Histochemical (trichrome, Elastic Van Gieson) and immunohistochemical stains (D2-40, CD68, keratin) aided in characterization of the lesions.

Conclusions: PIE was seen in 36% of adult explanted lung specimens, most commonly in patients with UIP. PIE was not limited to patients who were previously ventilated. These results may indicate that PIE is secondary to physiologic changes from the disease rather than an outside source, as is described in premature infants. Recognition of this unusual reaction is important, as the fibroinflammatory reaction may mimic other interstitial and infectious diseases.
Category: Pulmonary

Monday, March 4, 2013 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 286, Monday Morning


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