PO56 - Characterization of a Multicenter Portuguese Cohort with Unclassifiable Interstitial Lung Disease
Rita de Vasconcelos Pereira (Portugal)1; Ana Rita Ribeiro (Portugal)2; Andreia Daniel (Portugal)3; Carla Carvalho (Portugal)4; Pedro Vicente de Almeida (Portugal)5; Helena Carvalho (Portugal)6; Nuno Ferreira (Portugal)7; Luís Silva (Portugal)8; André Alexandre (Portugal)9; David Coelho (Portugal)9; Hélder Novais Bastos (Portugal)9; Patrícia Mota (Portugal)9; Natália Melo (Portugal)9; Susana Guimarães (Portugal)10; Conceição Souto Moura (Portugal)10; André Carvalho (Portugal)11; António Morais (Portugal)9;
1 - Serviço de Pneumologia, Hospital de Pedro Hispano - ULS Matosinhos; 2 - Serviço de Pneumologia, Hospital de Portimāo - ULS Algarve; 3 - Serviço de Pneumologia, Hospital Beatriz Ângelo – ULS Loures-Odivelas; 4 - Serviço de Pneumologia, ULS Braga; 5 - Serviço de Pneumologia, ULS Aveiro; 6 - Serviço de Pneumologia, ULS Santo António; 7 - Serviço de Pneumologia, ULS Tâmega e Sousa; 8 - Serviço de Pneumologia, ULS Entre Douro e Vouga; 9 - Serviço de Pneumologia, ULS São João; 10 - Serviço de Anatomia Patológica, ULS São João; 11 - Serviço de Radiologia, ULS São João;
Keywords: Unclassifiable interstitial lung disease; Multidisciplinary discussion; Interstitial lung disease;
Select the theme: Fibrotic Pulmonary Interstitial Fibrosis
Type: Original Papers
Presentation: Poster Presentation

Introduction: Unclassifiable interstitial lung disease (uILD) represents a heterogeneous subgroup of interstitial lung diseases characterized by overlapping features, in which a confident diagnosis cannot be established despite comprehensive evaluation, representing approximately 10–20% of cases.

Objectives: To characterize patients with uILD at the time of multidisciplinary discussion in order to better understand this heterogeneous phenotype.

Materials and Methods: A multicenter retrospective chart review was conducted between January-2015 and January-2026, identifying patients with a diagnosis of uILD established at multidisciplinary discussion. Patients were characterized regarding demographics, exposures, comorbidities, lung function and diagnostic procedures.

Results: A total of 75 patients were initially classified as uILD, most commonly due to the absence of biopsy (49.1%) or histological–radiological discordance (41.3%). The mean age at diagnosis was 68.5 years, with a predominance of males (70.7%) and current or former smokers (57.4%).

Comorbidities included diabetes mellitus (25.3%), gastroesophageal reflux (18.7%), heart failure (12%), and asthma (10.7%). Environmental exposures were frequent, particularly to birds (48%), moisture/mold (34.7%), and poultry (17.3%).

Dyspnea (74.7%) and cough (57.3%) were the main presenting symptoms, with inspiratory crackles detected in 74.7% of patients. At baseline, median of FVC was 78.3% [69.1-97.5] and DLCO 53.5% [43.4-64.6]; 22.9% had suspected pulmonary hypertension based on echocardiographic findings, and 14.7% required supplemental oxygen (long-term and/or portable).

Bronchoalveolar lavage was performed in 81.3% of patients, with lymphocytosis observed in 21.3%. Lung biopsy was performed in 53% patients, most commonly transbronchial lung cryobiopsy (n=34).

Median follow-up was 25 months [13.5–48.5], with an overall mortality of 24%, predominantly due to respiratory causes.

Conclusions: uILD remains a heterogeneous and clinically relevant entity. This cohort highlights the burden of smoking, comorbidities, and environmental exposures, along with substantial mortality, underscoring the need for improved diagnostic and therapeutic strategies.