Two cases of bronchopulmonary dysplasia of similar appearance in adult monozygotic twin: pathology and computed tomographic findings

Lung Transplantation for Bronchopulmonary Dysplasia in Adults: A Clinical and Pathologic Study of 3 Cases

Bronchopulmonary dysplasia (BPD) is usually seen in premature infants who require mechanical ventilation and oxygen therapy for acute respiratory distress. Although most patients wean from oxygen therapy by the ages of 2 to 3, rehospitalization for respiratory problems is common in these patients in adulthood. There have been few studies that document the long-term outcomes of BPD survivors and information about the pulmonary function and radiographic findings of adult BPD are limited. Data on pathologic features of adult BPD are scarce. Three adult patients who underwent recent lung transplantation for BPD from 2 institutions were identified. Clinical data including clinical presentation, chest radiographic images, pulmonary function tests, cardiac catheterization, and echocardiography were retrieved from the electronic medical records. Hematoxylin and eosin and selective elastic stained sections of the explant lungs were examined. CD31 immunohistochemical stain is performed on representative sections. All 3 cases had similar clinical and radiologic features including the history of prematurity and long-term mechanical ventilation after birth, hyperexpanded lungs with air trapping and mosaic attenuation on chest computed tomographic scan, severe obstructive changes on pulmonary function test, and pulmonary hypertension. Pathologic examination showed common features including enlarged and simplified alveoli, peribronchial, subpleural, and interlobular septal fibrosis, narrowing/obliteration of the small airways by elastosis and muscular hypertrophy, thickening of venous walls by fibromuscular hyperplasia, and bronchitis/bronchiolitis. Cholesterol granulomas were seen in 2 cases. The common pathologic findings in the lungs explain the clinical and radiologic findings. Future studies are warranted to further characterize the clinical and pathologic features of adult BPD to develop optimal management strategies for these patients.

Former-preterm lambs have persistent alveolar simplification at 2 and 5 months corrected postnatal age

Preterm birth and mechanical ventilation (MV) frequently lead to bronchopulmonary dysplasia, the histopathological hallmark of which is alveolar simplification. How developmental immaturity and ongoing injury, repair, and remodeling impact completion of alveolar formation later in life is not known, in part because of lack of suitable animal models. We report a new model, using former-preterm lambs, to test the hypothesis that they will have persistent alveolar simplification later in life. Moderately preterm lambs (~85% gestation) were supported by MV for ~6 days before being transitioned from all respiratory support to become former-preterm lambs. Results are compared with term control lambs that were not ventilated, and between males (M) and females (F). Alveolar simplification was quantified morphometrically and stereologically at 2 mo (4 M, 4 F) or 5 mo (4 M, 6 F) corrected postnatal age (cPNA) compared with unventilated, age-matched term control lambs (4 M, 4 F per control group). These postnatal ages in sheep are equivalent to human postnatal ages of 1-2 yr and ~6 yr, respectively. Multivariable linear regression results showed that former-preterm lambs at 2 or 5 mo cPNA had significantly thicker distal airspace walls ( P < 0.001 and P < 0.009, respectively), lower volume density of secondary septa ( P < 0.007 and P < 0.001, respectively), and lower radial alveolar count ( P < 0.003 and P < 0.020, respectively) compared with term control lambs. Sex-specific differences were not detected. We conclude that moderate preterm birth and MV for ~6 days impedes completion of alveolarization in former-preterm lambs. This new model provides the opportunity to identify underlying pathogenic mechanisms that may reveal treatment approaches.