Langerhans cell histiocytosis (LCH) describes a group of syndromes that share the common pathologic feature of infiltration of involved tissues by Langerhans cells. Typically, the skeletal system is involved, with a characteristic lytic bone lesion form that occurs in young children or a more acute disseminated form that occurs in infants.
Pulmonary involvement is not unusual in systemic forms of LCH, but symptoms are rarely a prominent feature.
Pulmonary Langerhans cell histiocytosis is considered a reactive proliferation of dendritic Langerhans cells to chronic tobacco-derived plant proteins resulting from incomplete combustion, but it can also occur as a tumor-like systemic disease in children.
CT scans of eosinophilic granuloma are depicted in the images below.
Chest CT in a patient with pulmonary eosinophilic granuloma demonstrates scattered cavitary and noncavitary nodules.
High-resolution chest CT scan in a patient with pulmonary eosinophilic granuloma shows the typical combination of nodules, cavitated nodules, and thick- and thin-walled cysts. Image courtesy of European Respiratory Society Journals LTD.
High-resolution chest CT scan in a patient with advanced pulmonary eosinophilic granuloma shows numerous pulmonary cysts of various sizes, which are confluent in some places. Image courtesy of European Respiratory Society Journals LTD.
Localized pulmonary LCH (also termed pulmonary eosinophilic granuloma) is a rare pulmonary disease that occurs predominantly in young adults. The precise incidence and prevalence of pulmonary LCH are unknown, although studies of lung biopsy specimens from patients with interstitial lung disease identified pulmonary LCH in only 5%.
A confident diagnosis of pulmonary LCH often can be made based on the patient’s age, smoking history, and characteristic high-resolution computed tomography (HRCT) scan findings, especially if patients are followed without treatment.
Definitive diagnosis, if necessary, can be made by identification of Langerhans cell granulomas in lung biopsy samples acquired by video-assisted thoracoscopy. Biopsy sites are selected on the basis of HRCT scan findings.
Transbronchial biopsy has a low diagnostic yield (10-40%) because of the patchy nature of the disease and the small amounts of tissue obtained.
Treatment consists of smoking cessation, which stabilizes symptoms in most patients. Corticosteroids are used in progressive or systemic disease. Cytotoxic agents (eg, cyclophosphamide) can be employed for patients who do not respond to smoking cessation and steroids. No treatment has been confirmed to be useful, and no double-blind therapeutic trials have been reported. Lung transplantation also has been performed for treatment of LCH.
In patients with suggested eosinophilic granuloma, obtain a chest radiograph and a chest HRCT scan.
The typical HRCT pattern of pulmonary Langerhans cell histiocytosis includes small poorly limited nodules, cavitated nodules, and thick- and thin-walled cysts. In rare cases, HRCT allows the disease to be diagnosed before the development of cysts.
In HRCT scanning, the small star-like scars can still be detected even after complete cessation of tobacco smoking.
Recent research cites the usefulness of positron emission tomography (PET)/CT scanning.