Pulmonary Langerhans cell histiocytosis (PLCH) is a rare interstitial lung disease. Its estimated prevalence is two to five cases per million. Young male adults develop the disease most frequently. Greater than 90% of cases of PLCH occur in smokers. Diabetes insipidus (DI) occurs in about 11% to 40% of patients and pneumothoraces occur in 10% to 30% of patients. The diagnosis of PLCH can be confirmed by BAL, transbronchial biopsy, or surgical lung biopsy. We present a case referred to us with dispnea developed after appendectomy operation, coexisting with DI, and diagnosed to have PLCH using transbronchial lung biopsy.