Pulmonary Langerhans Cell Histiocytosis

Abstract

Pulmonary Langerhans cell histiocytosis (PLCH) is a unique interstitial lung disease typically encountered in young smoking adults. The Langerhans cell is characterized by a grooved nuclear membrane and eosinophilic cytoplasm. Immunohistochemical stains help in establishing a definitive diagnosis for PLCH by staining positive for CD1a, human leukocyte antigen-DR, and S-100 protein. Chest radiography and thoracic computerized tomography scan in patients with PLCH typically shows upper lobe predominant nodules and cysts; the bizarre shape of the cysts is particularly evident on computerized tomography. Pulmonary function tests are helpful for prognostication at the time of diagnosis and throughout disease course. Spontaneous pneumothorax is common in patient with PLCH and 60% of patients have more than one episode. Surgical lung biopsy is considered the gold standard in the diagnosis of PLCH. A subgroup of patients with PLCH develop progressive disease with severe respiratory failure and premature mortality. No defined treatment is established although novel therapies are under development.