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A1602 - Clinical Diagnosis in Patients with Possible UIP Pattern on High-Resolution Computed Tomography Submitted to Surgical Lung Biopsy in Brazil
Author Block: R. C. C. Tibana1, M. R. Soares1, K. M. Storrer1, E. V. Mancuzo2, M. P. Rodrigues3, I. Missrie1, E. N. Coletta4, R. G. Ferreira1, C. A. D. C. Pereira4; 1Pulmonary, Paulista School of Medicine, Federal University of Sao Paulo, Sao Paulo, Brazil, Sao Paulo, Brazil, 2Pulmonary, Federal University of Minas Gerais, Brazil, Belo Horizonte, Brazil, 3Pneumology, University of Brasilia, Brasilia, Brazil, 4Paulista School of Medicine, Federal University of Sao Paulo, Sao Paulo, Brazil, Sao Paulo, Brazil.
Rationale: Some studies have suggested that possible usual interstitial pneumonia (UIP) pattern on high-resolution CT (HRCT) scan can provide sufficient diagnostic specificity to forgo surgical lung biopsy in the diagnosis of idiopathic pulmonary fibrosis (IPF), but this is dependent on underlying prevalence of IPF. In Brazil hypersensitivity pneumonitis (HP) is a common cause of interstitial lung disease (ILD). The objective of this study was to determine the prevalence of IPF and other ILD in patients with possible UIP submitted to surgical lung biopsies (SLB) in Brazil. Methods: Patients with biopsy-proven interstitial lung disease (ILD) and possible HRCT scans were identified from several ILD centers in Brazil. All scans were reviewed by consensus by a clinician and a radiologist with large experience in ILD, blinded to histopathology results and clinical information. After review, cases with UIP and inconsistent UIP pattern were excluded. All patients were submitted to SLB in all. All SLB were reviewed and interpreted by two expert pulmonary pathologists. Final clinical diagnoses were done by a multidisciplinary team discussion. Results: 61 patients, 67% males, mean age 65±7yr, 47% smokers/ex-smokers, were included in a retrospective study. Exposure to possible causative antigens for hypersensitivity pneumonitis (HP) was found in 33 (54%) of the 61 cases. Gastroesophageal reflux was confirmed in 18 cases. In two-thirds the findings on HRCT were predominant in lower lobes. In the remaining cases the distribution was diffuse. Bronchiolocentric fibrosis was the most common histologic pattern (55.7%; 95% CI: 42.4-68.5), followed by usual interstitial pneumonia (26.2%; 95% CI; 15.8-39.1). Fibroblastic foci were observed in 59% of total cases (95% CI: 47.7-71.4). The most common final diagnosis was HP (37.7%; 95% CI 25.6-51.0), followed by IPF (23%; 95%CI: 13.2-35.5) and fibrosis secondary to GERD (13.1%; 95% CI: 5.8-24.2). Absence of environmental exposure was associated with final diagnosis of IPF (p=0.001), but IPF was the final diagnosis in 43% (95% CI: 24.5-62.8) of 28 patients without exposure to possible HP, and in two cases with exposure (6.1%; 95% CI: 0.7-20.2), p=0.002. The addition of age, sex and a score for traction bronchiectasis score did not change the results. Conclusion: In Brazil, the most common disease associated with the HRCT pattern of possible UIP is HP, followed by IPF and bronchiolocentric fibrosis associated to GERD. In patients without environmental exposure, the frequency of UIP and a final diagnosis of IPF are not sufficiently high to avoid the indication of lung biopsy.