Bronchoalveolar lavage fluid analysis provides diagnostic information on pulmonary Langerhans cell histiocytosis

Histiocytes of Langerhans cell type are recovered from the bronchoalveolar lavage fluid (BALF) of patients with interstitial lung diseases in a nonspecific manner. Langerhans cells (LCs) can be identified through immunostaining for S-100, CD1a, and, more specifically, langerin. To evaluate the diagnostic value of BALF in pulmonary Langerhans cell histiocytosis (PLCH), we performed a retrospective clinicopathological study of 5 patients with biopsy-confirmed PLCH or Hand-Schüller-Christian disease involving the lung. As a control study, we examined BALF cells from 23 patients with various diseases, including sarcoidosis, hypersensitivity pneumonitis, collagen vascular disease, idiopathic pulmonary fibrosis, and adenocarcinoma of the lung. Cytospins obtained from BALF were stained with Giemsa or Papanicoloau and others were immunostained. In general, cytospins showed a monomorphous and dispersed cell population containing mononucleated or binucleated and occasionally multinucleated histiocytes. LCs recovered from BALF were characterized by clear and velvety cytoplasm; oval or kidney-shaped, vesicular nuclei with irregular shapes; nucleoli; and frequent grooves and indentations. Radiography and high-resolution computed tomography showed multiple bilateral nodular or cystic lesions in the middle and upper lung zones. The mean percentage of LCs in 9 lavages from the 5 patients was 8.0%, whereas that from the control group was only 0.3% (maximum, 1.6%). The percentage of cells positive for S-100 or CD1a was comparable to the percentage of Langerhans-like histiocytes stained with Giemsa stain. The present results indicate that the survey of LCs in BALF with the aid of immunocytochemical evaluation and corresponding clinical data could play a critical role in establishing the diagnosis of PLCH, thus providing a less invasive approach than lung biopsy, which carries a risk of complications.