[2029] Histopathological Findings of Usual Interstitial Pneumonia (UIP) and Non- Specific Interstitial Pneumonia (NSIP) in 34 Explants

Maud Rabeyrin, Francois Thivolet, Gilbert Ferretti, Lara Chalabreysse, Laurent Thomas, Vincent Cottin, Christophe Pison, Jean-Francois Cordier, Sylvie Lantuejoul. CHU A Michallon, INSERM U823, Université J Fourier, Grenoble, France; Hospices Civils de Lyon, INSERM U331, Université Claude Bernard Lyon I, Lyon, France; Hospices Civils de Lyon, Université Claude Bernard Lyon I, INSERM UMR754 and IFR128, Lyon, France

Background: Idiopathic pulmonary fibrosis (IPF) is the most frequent and serious idiopathic interstitial pneumonia, with a histological pattern of Usual Interstitial Pneumonia (UIP) and typical HRCT findings; its main differential diagnosis is Non-Specific Interstitial Pneumonia (NSIP). Most histological criteria for interstitial pneumonia have been described from biopsies, and little is known on explants' findings with the exception of one previous study (A.-L. A. Katzenstein et al. 2002).
Design: Histological features of 34 UIP or F-NSIP explants were retrospectively analysed blinded to clinico-radiological data, and compared with 20 previous biopsies and HRCT. As patients had underlying diseases, the corresponding specimens were considered separately.
Results: Final consensus diagnoses were 22 IPF/UIP (including 3 exacerbated), 4 idiopathic fibrosing NSIP (F-NSIP), and 8 non-idiopathic fibroses with F-NSIP pattern (n=3) or UIP pattern (n=5). Concordance between radiologists and pathologists was only for IPF diagnosis (19/22 cases versus 18/22 cases, respectively). Temporo-spatial heterogeneity of fibrosis and sub-pleural and para-septal distribution were found in 91% to 95% of IPF/UIP explants and biopsies. High fibroblastic foci mean score and honeycombing predominated in explants, whereas normal lung was rare. NSIP areas were observed in 7/11 of IPF/UIP biopsies and in 9/19 of IPF/UIP explants. Most UIP explants showed an extension of the fibrotic process around bronchioles; large enlargements of restructured airspaces were observed in 13/22 (59%) explants and in 5/11 (45%) biopsies, in association with emphysema in 10 patients with lower lobe fibrosis and upper lobe emphysema on HRCT.
Conclusions: We confirm that temporo-spatial heterogeneity of fibrosis, its sub-pleural and para-septal distribution, fibroblastic foci and honeycombing are constant findings in IPF/UIP explants; we emphasize the high frequency of NSIP and large cystic airspace enlargements, this end-stage disease lesion being not frequently reported on open lung biopsies.
Category: Pulmonary

Tuesday, March 20, 2012 1:00 PM

Platform Session: Section D, Tuesday Afternoon


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