Distinct characteristics of pleuroparenchymal fibroelastosis with usual interstitial pneumonia compared with idiopathic pulmonary fibrosis

Pleuroparenchymal fibroelastosis: Distinct pulmonary physiological features in nine patients

BACKGROUND

Pleuroparenchymal fibroelastosis (PPFE) is a rare idiopathic interstitial pneumonia defined by pleural and subpleural parenchymal fibrosis predominantly in the upper lobes. Although the radiological and pathological characteristics of PPFE have become increasingly recognized, its pulmonary physiological features are not well understood.

METHODS

We reviewed nine patients with radiologically and histologically proven PPFE, and evaluated pulmonary physiological data.

RESULTS

Of the nine patients, six were male and three were female. The median age at presentation was 61 years. Common symptoms were dyspnea on exertion, weight loss, and nonproductive cough. Recurrent pneumothorax was found in eight patients and pneumonia in four. Median pulmonary function test results were as follows: forced vital capacity, 55.4% predicted; total lung capacity (TLC), 67.1% predicted; residual volume (RV), 102.3% predicted; and RV/TLC, 143.6% predicted. RV/TLC was increased without evidence of small airway disease according to clinico-radiologic-pathologic evaluation. The median partial pressure of oxygen in arterial blood and the alveolar-arterial gradient of oxygen were within normal limits, although there was a slightly elevated partial pressure of carbon dioxide in arterial blood (PaCO2). PPFE progressed in all patients despite treatment with pirfenidone, corticosteroids, and immunosuppressive agents. Seven patients died during the follow-up, five because of hypercapnic respiratory failure.

CONCLUSIONS

PPFE is characterized by severe mechanical restriction with high RV/TLC, causing increased PaCO2 and eventual hypercapnic respiratory failure. These physiological findings may be useful as an adjunct in the diagnosis of PPFE.

Changes in the current classification of IIP: A critical review

Idiopathic interstitial pneumonias (IIP) are a heterogeneous group characterized by unknown aetiology. Establishment of a correct diagnosis of a distinct IIP requires a multidisciplinary approach integrating clinical presentation, physiological data, radiological appearance and histological findings. The 2013 update of the American Thoracic Society/European Respiratory Society classification summarises progress in the field of IIP and outlines potential areas for future research. The main entities defined by the 2002 statement on IIP are preserved, but major IIP are now distinguished from rare IIP and the new category of unclassifiable IIP is introduced. In addition, the existence of idiopathic non-specific interstitial pneumonia as a separate chronic fibrosing IIP and idiopathic pleuroparenchymal fibroelastosis as a specific rare entity are acknowledged. Moreover, the major IIP are categorized according to the features chronic fibrosing, smoking-related and acute/subacute clinical course. Furthermore, a clinical classification of IIP according to disease behaviour with suggestions for treatment goals and monitoring strategies is provided. The goal of this review is to discuss the areas of uncertainty in the updated multidisciplinary classification of IIP and point out potential consequences for clinical management.