The place of the bronchoalveolar lavage in the diagnosis of interstitial lung disease: a descriptive and qualitative study

Background: Interstitial lung disease represents a challenge and consists in more than 200 entities. Their diagnoses are assessed through a multidisciplinary approach including pulmonologists, radiologists, pathologists and biologists. BAL analysis is useful mainly when clinical and radiological findings aren’t suggestive of an etiology. Even if, the indication of BAL is consensual, its real place as a diagnostic mean remains non consensual. Aim: To describe the BAL findings and to analyse the perceptions of the pulmonologists, anaesthesiologists and pathologists implicated in the interpretation of the BAL data, that are related to the presentation and the validity of the results. Methods: the authors performed a descriptive study about BAL results during an 8-year-period (2010-2018) and a qualitative study assessing the pulmonologists, anaesthesiologists and pathologists’ opinions concerning the different results performed in the same institution. Two questionnaires were conceived with participation of different experts and satisfaction scores were calculated. Results: 2508 BAL were recorded including 1320 women (53%) and 1188 men (47%) with a sex-ratio (H/F) of 0,9. The mean age of the patients was 51 years. The mean response delay was 3.25 days. An accurate diagnosis was retained in 24.3%. It consisted in infection evoked in 13.89% cases. Eosinophilic pneumonia was evoked in 0.35% cases. 15.01% cases presented erythrophagocytosis with a golde score>100 favouring active alveolar haemorrhage with occult alveolar haemorrhage. Lipoproteinosis was diagnosed in 2 cases. Adenocarcinoma was retained in 1.04% cases and lymphoma in 0.16% cases. Langerhans cell histiocytosis was confirmed in 1.51% cases. In the other cases, cellular profile was not specific evoking tuberculosis or sarcoidosis in 316 cases with a CD4/CD8 ratio superior to 1,6 and the diagnoses of tuberculosis or hypersensitivity pneumonia in 202 cases with a CD4/CD8 ratio inferior to 1,2. Concerning the questionnaire-based study, 50 pulmonologists and anaesthesiologists attributed a mean score of 7.96/10 (DS=0.55) concerning the presentation of the results and 9.28/15 (DS=0.77) concerning the quality and validity of the results. On the other hand, the mean satisfaction score rated by pathologists reached 24/40. Conclusion: BAL results could be helpful for the management of interstitial lung disease depending on the experience of pathologists and a good communication between pulmonologists, anaesthesiologists and pathologists.