You are in: eMedicine Specialties > Radiology > CHEST Eosinophilic Granuloma, ThoracicArticle Last Updated: Jun 10, 2005AUTHOR AND EDITOR INFORMATIONSection 1 of 10
  Author: Scott C Williams, MD, Section Chief, Nuclear Medicine Associate Attending Radiologist, Advanced Radiology Consultants, Bridgeport Hospital Scott C Williams is a member of the following medical societies: American College of Radiology, American Medical Association, American Roentgen Ray Society, and Radiological Society of North America Coauthor(s): Matthew D Gilman, MD, Chief of Thoracic Imaging Section, Department of Radiology, Madigan Army Medical Center Editors: Jeffrey A Miller, MD, Associate Professor of Clinical Radiology, University of Medicine and Dentistry of New Jersey; Associate Chief of Service, Department of Radiology, Veterans Affairs of New Jersey Health Care System; Bernard D Coombs, MB, ChB, PhD, Consulting Staff, Department of Specialist Rehabilitation Services, Hutt Valley District Health Board, New Zealand; John D Newell, Jr, MD, FACR, FCCP, FASER, Co-Director of Thoracic Imaging, UCDHSC; Director of Lung Imaging Center, Professor of Radiology and Professor of Medicine, Department of Radiology, University of Colorado Health Sciences Center, National Jewish Medical and Research Center; Univ. Colorado Hospital; Robert M Krasny, MD, Consulting Staff, Department of Radiology, The Angeles Clinic and Research Institute; Barry H Gross, MD, Professor, Department of Radiology, University of Michigan Medical School; Professor, University of Michigan Cancer Center Author and Editor Disclosure Synonyms and related keywords: pulmonary Langerhans cell granulomatosis, pulmonary Langerhans cell histiocytosis, LCH INTRODUCTIONSection 2 of 10
  BackgroundLangerhans 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. Localized pulmonary LCH (also termed pulmonary eosinophilic granuloma [EG]) 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%. PathophysiologyPulmonary involvement in LCH is characterized by a granulomatous infiltration of the alveolar septa and bronchial walls by Langerhans cells that produce small, 1-5 mm nodules. The infiltrate can result in progressive lung destruction and widespread cystic change. Langerhans cells are one part of the widespread system of "dendritic cells" that arise from bone marrow stem cells and normally are present in the lung. Cytoplasmic immunostaining with S100 antigen distinguishes them from histiocytes. Other unique features of Langerhans cells are (1) the presence of Birbeck granules (rod-shaped intracellular structures identified by electron microscopy) and (2) the presence of CD1a antigen on the cell surface. As a result of these features, some authors prefer to term the disorder Langerhans cell "granulomatosis," since the Langerhans cell is not a member of the mononuclear phagocytic system (ie, not a macrophage or "histiocyte"). Since Langerhans cells may be identified in several pathologic pulmonary processes, the presence of pulmonary Langerhans cells is not diagnostic of pulmonary LCH. FrequencyUnited StatesLCH is rare and is responsible for only 3.4-5% of patients with chronic diffuse interstitial lung disease. InternationalSee Frequency in the US. Mortality/MorbidityThe course of pulmonary disease varies. Remission occurs in approximately 25-30% of patients, stabilization in 30-50%, and progression of the disease in 25-30%. Death from respiratory failure or cor pulmonale occurs in 5%. Asymptomatic or minimally symptomatic patients tend to have the best outcomes. Decreased survival is associated with the following:
RaceLCH usually affects whites. The disorder is rare in blacks. SexMale-to-female ratio is equal, although young men appear to have the worst prognosis. AgePatients with isolated pulmonary EG usually are young adults aged 20-40 years. Clinical DetailsA strong association exists between pulmonary LCH and smoking (90-95% of patients are smokers). Symptoms often improve with the cessation of smoking. No known genetic factors predispose patients to pulmonary LCH. Of LCH patients, 25-33% are asymptomatic at presentation. Symptomatic patients may present with the following:
Pulmonary function tests do not provide consistent findings, but mild airway obstruction is common. A reduction in carbon monoxide diffusion capacity is present in 60-90% of patients. On bronchoalveolar lavage (BAL), an increased number of cells are seen, particularly macrophages; however, this may be a manifestation of the patient's smoking history. Langerhans cells also can be found on BAL. A diagnosis of pulmonary LCH is likely when the proportion of Langerhans cells in the BAL fluid is greater than 5%, although this finding is not specific for the disorder. A confident diagnosis of pulmonary LCH often can be made based on the patient's age, smoking history, and characteristic high-resolution CT findings, especially if patients are followed without treatment. When tissue confirmation is required, make the diagnosis using open lung biopsy via video-assisted thoracoscopy. 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 Treatment consists of the cessation of smoking, 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 useful, and no double-blind therapeutic trials have been reported. Lung transplantation also has been performed for treatment of LCH. No specific criteria exist for determining which pulmonary LCH patients are candidates for lung transplantation. Patients with rapidly declining lung function, severe pulmonary symptoms, and a lack of response to other treatments are the best candidates for transplant consideration; however, the disorder may recur in the transplanted lung. Etiology Etiology of the disorder is not known. The bronchocentricity and the tendency of the disease to regress following the cessation of smoking suggest a reactive immune response in the bronchioles to an inhaled antigen in cigarette smoke that is mediated by the Langerhans cell system. The recurrence of the disease after transplantation suggests that extrapulmonary factors also are involved in disease pathogenesis or that the condition may represent a neoplastic disorder. An association between EG and lymphoma has been described. Bronchogenic carcinoma has been identified with increased frequency in patients with pulmonary LCH. Lung scarring and smoking may contribute to the development of lung cancer in these patients. Although intriguing, evidence likely is insufficient to either prove or refute the association between pulmonary LCH and malignant neoplasms. Preferred ExaminationIn patients with suggested EG, obtain a chest radiograph and high-resolution chest CT. DIFFERENTIALSSection 3 of 10
| ||||||||||||
| Media file 1: Chest CT in a patient with pulmonary eosinophilic granuloma demonstrates scattered cavitary and noncavitary nodules. | |
 | View Full Size Image | Media type: CT |
Eosinophilic Granuloma, Thoracic excerpt
Article Last Updated: Jun 10, 2005
