Definition
A form of interstitial lung disease due to the proliferation of Langerhans' cells. Isolated pulmonary disease is probably non-neoplastic3, in contrast to most extra-pulmonary Langerhans cell proliferations.
Most cases of isolated Langerhans' cell histiocytosis of the lung occur in adults, of whom over 95% are smokers or ex-smokers3. 15% of adult cases have extrapulmonary disease: pulmonary involvement with systemic Langerhans' cell histiocytosis occurs more often in children. The mean age of pulmonary adult cases is forty years. There may be an increased risk of developing other malignancies2.
A minority of patients are asymptomatic. Symptoms consist of cough, dyspnea, chest pain, malaise, weight loss and fever. Most patients have abnormal pulmonary function tests, which may be restrictive, obstructive or a deficit in diffusion capacity.
Disease is predominantly of upper and mid zones2, with sparing of the costophrenic angles, consisting of (micro)nodules with cystic change2,3. Honeycomb fibrosis is rare3.
Most patients, being smokers, also have emphysema and respiratory bronchiolitis. The lesions of PLCH consist of cellular stellate proliferations of Langerhans' cells and eosinophils around small airways. They progress from cellular to fibrotic, eventually being devoid of recognizable Langerhans' cells. Langerhans' cells have pale eosinophilic cytoplasm and delicately folded nuclear membranes.
Langerhans' cells are positive for S-100 and CD1a. See immunohistochemistry of systemic Langerhans' cell histiocytosis.
Birbeck granules are characteristic of Langerhans' cells.
Smoking cessation and steroids2.
15% of patients show progressive disease; progression may be slow. The five year survival is 75%, the ten year survival is 65% and the median survival is 12.5 years2.
0 Tumours of the Lung, Pleura, Thymus and Heart. WHO Classification of Tumours. IARC Press 2004.
This page last revised 4.4.2005.
©SMUHT/PW Bishop