Pulmonary Langerhans cell histiocytosis incidentally detected during routine follow-up of nasopharyngeal carcinoma

Aim Langerhans cell histiocytosis (LCH) is a rare disease originating from myeloid dendritic cells with an unknown etiology. As well as multiorgan involvement, it can also be seen symptomatically or incidentally in the lungs. In this study we aimed to present a case of pulmonary Langerhans cell histiocytosis (PLCH) incidentally detected during routine follow-up of a patient with nasopharyngeal carcinoma. Case A 66 year-old male who complained of hoarseness was diagnosed with locally advanced nasopharyngeal cancer and treated with chemoradiotherapy curatively. Then he involved follow up program and in post treatment eighteenth month newly developed metastasis suspicious pulmonary parenchymal lesions were detected. On chest computed tomography (CT) scan lesions were cystic in nature and were located in the apicoposterior segments. The patient was operated after discussed in the multidiscipliner thorax council. Post operative pathologic evaluation revealed cystic and noduler structures composed of langerhans cells. Immunohistochemical examination showed diffuse positivity in the langerhans cells with S-100 and CD1 antigen (CD1a). Thus case was diagnosed with (PLCH). Conclusion PLCH is an uncommon and smoking related intertisial lung disease. It usually has a good prognosis especially after smoking cessation.