Is bronchoalveolar lavage useful in the diagnosis and management of interstitial lung disease? Meyer and Raghu believe so (although their manuscript title suggests they're not 100% sure). They explain why in the October ERJ.
They argue that if interpreted in the right clinical context, certain bronchoalveolar lavage findings can help cinch the diagnosis of ILD:
- Lymphocytes >= 25%: granulomatous or lymphocytic disease likely present (sarcoidosis, BOOP/COP, lymphoproliferative disorder, drug reaction, cellular NSIP, hypersensitivity pneumonitis, chronic beryllium disease, or LIP)
- Eosinophils >=25%: eosinophilic pneumonia
- Neutrophils >=50%: infection, acute interstitial pneumonitis, diffuse alveolar damage, or acute exacerbation of idiopathic pulmonary fibrosis
- CD1a+ cells > 4% on flow cytometry: pulmonary Langerhans cell histocytosis
If there are >5% squamous cells, the sample may be contaminated by oral secretions (or the person aspirated some). If there are >5% bronchial epithelial cells, it may not be a true alveolar sample and may therefore be unsuitable.
These authors argue against the routine use of flow cytometry in evaluating ILD; they feel the standard cited patterns (e.g. for CD4/CD8 ratio) are too insensitive and nonspecific to aid in diagnosis of sarcoidosis or HP.
The joint ATS/ERS/JRS/ALAT 2011 expert statement on evaluation for possible IPF does not recommend routine BAL in that setting, instead recommending that BAL be considered on a case-by-case basis at expert centers that can perform accurate cell count & differentials and interpret the results.
Meyer KC, Raghu G. Bronchoalveolar lavage for the evaluation of interstitial lung disease: is it clinically useful? Eur Resp J 2011;38(4):761-769.