Pulmonary langerhans cell histiocytosis (histiocytosis X) on bronchoalveolar lavage: a report of 2 cases.

Background: Pulmonary Langerhans cell histiocytosis (PLCH) is an interstitial lung disease characterized by bilateral nodular and cystic lesions. Clinically it seems to be a reactive process related to cigarette smoking.

Cases: In 2 cases of PLCH, cytologic and immunocytochemical evaluation of bronchoalveolar lavage (BAL) fluid was successfully used for the diagnosis of PLCH. Two heavy smokers complained of fever, cough and debilitation. Serologic and hematologic values were normal. In both cases radiography and computed tomography (CT) were similar, showing multiple bilateral nodular or cystic lesions in the middle and upper lung zones. Cytospins obtained from BAL were Papanicolaou and May-Grünwald-Giemsa stained; others were immunostained with cytokeratin cocktail, CD1a and S-100. Cytospins showed a monomorphous and dispersed cell population consisting ofmononucleated or binucleated and occasionally multinucleated histiocytes. Single cells showed wide, well-defined, acidophilic cytoplasm and oval or kidney-shaped, vesicular nuclei with irregular shapes, evident nucleoli and frequent grooves and indentations. Immunocytochemical staining showed diffuse cytoplasmic positivity for S-100 and CD1a and negativity for cytokeratin; only the few cylindrical cells present in the cytospins were positive for cytokeratin. In both cases the cytologic diagnosis of PLCH was confirmed by subsequent CT and clinical follow-up.

Conclusion: Cytologic and immunocytochemical evaluation of BAL fluid permits a definitive diagnosis of PLCH. This cytologic diagnosis is clinically relevant because it permits surgical biopsy to be bypassed and allows waiting for a possible spontaneous or pharmacologic resolution.