AUTHOR AND EDITOR INFORMATION

Section 1 of 13  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Further Reading
• Acknowledgments
• Multimedia
• References

INTRODUCTION

Section 2 of 13  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Further Reading
• Acknowledgments
• Multimedia
• References

Background

Eosinophilic granuloma, also known as pulmonary histiocytosis X (PHX) or pulmonary Langerhans cell histiocytosis X (PLCH), is an uncommon interstitial lung disease that is epidemiologically related to tobacco smoking. It chiefly affects young adults, primarily occurring in the third or fourth decades of life.

See also Eosinophilic Granuloma, Skeletal and Eosinophilic Granuloma, Thoracic for a radiological perspective. Additionally, the Medscape General Medicine article Lymphangioleiomyomatosis may be helpful, as may a reader comment and author response related to this article.

Pathophysiology

PLCH is histologically characterized by abnormal infiltration of the lungs by activated Langerhans cells. Langerhans cells are differentiated cells of the dendritic cell system and are closely related to the monocyte-macrophage line. These antigen-presenting cells are normally found in the skin, reticuloendothelial system, heart, pleura, and lungs. They may be identified by immunohistochemical staining or by the presence of Birbeck granules via electron microscopy.  

PLCH is similar to pediatric histiocytic disorders (Letterer-Siwe disease and Hand-Schuller-Christian disease). However, in contrast to pediatric histiocytoses, which involve multiple organs, PLCH usually manifests in a single organ; the lung. About 4-20% of patients with PLCH also have cystic lesions in the bones. Other organ systems are only rarely affected.

The accumulation found in the lungs is hypothesized to occur in response to exposure to cigarette smoke. Supporting this hypothesis is the finding that the initial histologic and radiographic findings are peribronchiolar. In addition, the disease is most prominent in the upper and middle lung zones, as seen in other smoking-related lung diseases. The granulomatous infiltrates seen in PLCH are composed of Langerhans cells, eosinophils, lymphocytes, macrophages, plasma cells, and fibroblasts, which form nodules centered on the terminal and respiratory bronchioles, causing destruction of the airway walls. In late stages of the disease, fibrotic stellate scarring occurs, and end-stage PLCH is characterized by this scarring along with cystic spaces and honeycombing.

Frequency

United States

PLCH is a rare disorder and the true prevalence is unknown. At 1 specialty referral center in the United States, PLCH was identified in less than 5% of patients who underwent lung biopsy for the diagnosis of interstitial lung disease.¹ At another center, 15 cases of PLCH were found after lung biopsy, compared with 274 cases of sarcoidosis.²

International

In Belgium, 3% of patients evaluated at 20 pulmonary referral centers were diagnosed with PLCH.³ A large Japanese study estimated the prevalence of PLCH at 0.27 males and 0.07 females per 100,000 population based on hospital discharge diagnoses over a 1-year period.⁴ Scant epidemiologic data are available regarding this disease in the developing world.

Mortality/Morbidity

• PLCH has a highly variable course. Some patients have spontaneous remissions, especially when they stop cigarette smoking, whereas others progress to end-stage fibrotic lung disease.
• In 1 retrospective study, median survival was 12.5 years after diagnosis.⁵ A European study showed similar findings, with a median survival of 13 years.⁶
• Factors associated with a poorer prognosis include multisystem involvement other than bone (including diabetes insipidus related to pituitary involvement), recurrent pneumothorax, severe pulmonary artery hypertension, older age at diagnosis, severe pulmonary function test abnormalities, and more widespread cystic changes on imaging studies.
• Cigarette smoking is important to disease activity. Smoking worsens morbidity and mortality. Smoking cessation frequently stabilizes the disease and sometimes leads to its regression.

Race

Because of the rarity of the disease, no definitive epidemiologic data related to racial background are available.

Sex

No sex predilection is recognized.

Age

The peak incidence occurs in the 20- to 40-year age bracket.

CLINICAL

Section 3 of 13  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Further Reading
• Acknowledgments
• Multimedia
• References

History

Presentations are variable. Approximately 25% of patients are asymptomatic, and their disease is diagnosed after an evaluation of incidental findings on chest radiographs. Others present with respiratory or constitutional symptoms. In order of decreasing frequency, common presenting symptoms are as follows:

• Nonproductive cough (56-70%)
• Dyspnea (40%)
• Fatigue (30%)
• Weight loss (20-30%)
• Chest pain (21%)
• Spontaneous pneumothorax, which may be recurrent, is a classic presentation found in 10-20% of patients.
• Fever (15%)
• Cystic bone lesions (4-20%): These may be painful and may predispose the patient to pathologic fracture.

Physical

Patients with PLCH present with nonspecific physical findings. Neither inspiratory rales (crackles) nor clubbing is common. Cor pulmonale may develop; therefore, the following related findings may be present:

• Loud second heart sound with accentuated pulmonic component
• Tricuspid regurgitation murmur
• Right ventricular lift
• Peripheral edema

Causes

No occupational causes or geographic predispositions are recognized. People with PLCH, almost invariably, are cigarette smokers. Antigenic stimulation from 1 or more components of tobacco smoke is likely responsible for the disease. Because only a few tobacco smokers develop the disease, other susceptibility factors, such as host genetics and environmental exposures, most likely play an important role in pathogenesis. Some reports in the literature also describe PLCH developing following radiation and/or chemotherapy for lymphoma. Additional investigation is needed to further our understanding of this disease process.

DIFFERENTIALS

Section 4 of 13  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Further Reading
• Acknowledgments
• Multimedia
• References

Other Problems to be Considered

• Tuberous sclerosis
• Lymphangioleiomyomatosis (LAM): Patients with PLCH frequently present to medical attention with spontaneous pneumothoraces. Lymphangioleiomyomatosis is a disorder that exclusively affects young women and is characterized by cystic, emphysematous dilation of the terminal airways and shares this predisposition. It may be mistaken for PLCH on a chest radiograph or high-resolution CT (HRCT) scan of the chest.

WORKUP

Section 5 of 13  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Further Reading
• Acknowledgments
• Multimedia
• References

Lab Studies

• Results from routine laboratory testing are nonspecific.
• Peripheral eosinophilia is not observed.

Imaging Studies

• Chest radiographs characteristically reveal bilateral, symmetric, ill-defined nodules and reticulonodular infiltrates. As the disease progresses, cystic lesions appear. An upper-zone predominance of radiographic findings with sparing of the costophrenic angles is typically observed.
• • Cystic lesions can be of various sizes and thin or thick walled.
  • Lung volume is normal or increased.
  • Honeycombing indicates advanced disease.
  • Bony lesions may occur on the ribs or any other site.
  • Hilar or mediastinal adenopathy is rare and should prompt the consideration of sarcoidosis or malignancy.
  • Pleural effusion is uncommon.
• HRCT of the chest may be virtually diagnostic in the appropriate clinical setting. Pathognomonic findings include nodules and cysts, predominantly in the mid and upper lung zones, with sparing of the costophrenic regions. The nodules may be cavitary and variable in size. Likewise, the cysts may be of various diameters and wall thicknesses. A broad differential diagnosis must be considered in the following situations:
• • If only nodules are present on HRCT, the findings are nonspecific, and a number of other granulomatous disorders cannot be excluded radiographically.
  • When cysts are an isolated finding, LAM must be considered as well. Unlike PLCH, LAM is usually uniformly distributed throughout the lungs. Sparing of the costophrenic angles supports a diagnosis of PLCH.
  • Emphysema is usually distinguishable, as walls do not surround the cystic spaces found in emphysema. However, extensive emphysema is sometimes difficult to differentiate from PLCH.

Other Tests

• Pulmonary function testing can demonstrate all patterns of abnormality: Normal, restrictive, obstructive, or mixed.
• • Most patients have normal or near-normal total lung capacity with near-normal spirometry findings.
  • Gas exchange, as measured by the diffusing capacity for carbon monoxide, is generally reduced.
  • In rare cases, patients have reversible airflow limitation.
• Gas exchange abnormalities may be present at rest. Although such abnormalities are most pronounced with exercise, most patients have a normal gradient of alveolar-arterial partial pressures.
• Pulmonary exercise testing may demonstrate decreased exercise capacity with reduced oxygen utilization. Gas exchange, ventilatory, and pulmonary vascular abnormalities may also be present. Therefore, exercise limitation is generally multifactorial.

Procedures

• Analysis of bronchioalveolar lavage (BAL) fluid is sometimes diagnostic.
• • A greater than 5% increase in the number of Langerhans cells in BAL specimens is almost pathognomonic for PLCH. Although this finding is highly specific, it is not particularly sensitive.
  • Langerhans cells can be recognized by their characteristic staining for S-100 protein or peanut agglutination antigen.
  • These cells are CD1a-positive, and may also be identified by a specific monoclonal antibody (MT-1).
• Although the disease is present in a patchy distribution, sometimes transbronchial biopsy may be diagnostic if sampling is done in a number of areas and sufficient tissue is obtained.
• • Immunostaining for Langerhans cells (CD1a) improves the sensitivity and specificity of the biopsy sample.
  • The diagnostic yield is approximately 10-40%.
• Open or thoracoscopic lung biopsy is the most sensitive and specific diagnostic modality, and is generally recognized as the criterion standard.
• • In addition to immunostaining, electron microscopy of tissue samples may be performed.
  • Langerhans cells demonstrate the characteristic intracytoplasmic Birbeck granules. These are found in all Langerhans cells, but they are present in increased numbers in the pathologic Langerhans cells found in the lesions of PLCH.

Histologic Findings

The earliest lesions consist of Langerhans cells grouped around the small airways. These inflammatory lesions expand to form granulomatous nodules composed of Langerhans cells as well as eosinophils, macrophages, lymphocytes, plasma cells, and fibroblasts.

In addition to looking for the typical morphologic features of Langerhans cells, immunostaining for S-100 and CD1a may also be useful. Electron microscopy helps in identifying Langerhans cells by demonstrating the presence of diagnostic pentilaminar cytoplasmic inclusion bodies, or Birbeck granules (x-bodies).

Of note, eosinophils may not always be present. Therefore, the name eosinophilic granuloma, despite being a commonly accepted term, is a misnomer.

Granulomas are centered on distal bronchioles. Evidence of pulmonary vascular involvement and respiratory bronchiolitis are often present, as well as infiltration and destruction of airway walls. As the disease progresses, cavitation occurs as a result of this destruction. The nodule fibroses, eventually forming a stellate scar.

TREATMENT

Section 6 of 13  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Further Reading
• Acknowledgments
• Multimedia
• References

Medical Care

Smoking cessation is the most important medical intervention. Smoking cessation often stabilizes the disease and sometimes leads to regression. It is also helpful in preventing bronchogenic carcinoma. Largely because of the rarity of PLCH, well-designed, prospective, randomized data regarding therapy are lacking. Treatment considerations are as follows:

• The use of corticosteroids is controversial. Corticosteroids may be considered in patients with a persistence of clinically significant pulmonary or constitutional symptoms or those with documented progression of disease. Corticosteroid therapy is not indicated in patients with normal lung function. Recommendations for the use of corticosteroids are based largely on retrospective data and expert opinion.
• Investigational therapies include interleukin-2 (IL-2) and anti–tumor necrosis factor-alpha (anti–TNF-alpha). Both agents have been reported to improve outcomes in pediatric disseminated histiocytosis. This finding may lead to the investigation of their use in adult PLCH.
• Useful adjunctive therapies include the following:
• • Supplemental oxygen therapy for those with clinically significant hypoxemia (SaO₂ <89% or PaO₂ <55 mmHg) at rest or with exertion
  • Aggressive treatment for pulmonary infections with prompt initiation of antibiotic therapy
  • Bronchodilator therapy in the presence of an obstructive ventilatory defect

Surgical Care

Lung transplantation is an option for select patients with advanced disease. Recurrence of PLCH has been reported in the transplanted lung.⁷

Consultations

Refer patients with suspected PLCH to a pulmonary disease specialist.

Activity

Exercise and pulmonary rehabilitation are encouraged. These activities may improve the patient's functional status, even if they have no effect on disease progression.

MEDICATION

Section 7 of 13  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Further Reading
• Acknowledgments
• Multimedia
• References

The mainstays of treatment for PLCH are smoking cessation and supportive therapy. The use of corticosteroids in the treatment of PLCH is controversial. Their efficacy has not been proven in well-designed, prospective, randomized, controlled trials. Some experts recommend a trial of corticosteroids for those patients with persistent symptomatic disease or evidence of progression.

Drug Category: Corticosteroids

These agents have anti-inflammatory properties and cause profound and varied metabolic effects. Corticosteroids modify the body's immune response to diverse stimuli.

FOLLOW-UP

Section 8 of 13  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Further Reading
• Acknowledgments
• Multimedia
• References

Further Inpatient Care

• Inpatient admission is indicated only to manage complications related to the disease as listed below.
• Patients with superimposed respiratory infections, such as pneumonia, may require inpatient treatment.
• Patients with spontaneous pneumothorax may require chest-tube placement and subsequent in-patient care. The recurrence rate of secondary spontaneous pneumothorax in PLCH is high. Therefore, some experts recommend surgical intervention, such as mechanical pleurodesis, parietal pleurectomy, or talc insufflation, to prevent further occurrences after the initial episode.
• Acute respiratory failure necessitating in-patient management may occur as the result of a superimposed respiratory infection or spontaneous pneumothorax. Respiratory failure may also occur as a manifestation of end-stage disease.

Further Outpatient Care

• In the care of patients with PLCH, important considerations include the patients' smoking history and current smoking status, the presence or absence of extrapulmonary disease and constitutional symptoms, and close monitoring for progression of pulmonary disease.
• Pulmonary artery hypertension is a known complication of infiltrative lung diseases, and in PLCH the magnitude of pulmonary artery hypertension may be greater than expected for given the degree of hypoxemia or level of impairment on pulmonary function testing.
• The increased risk of pulmonary malignancies must be considered.
• Smoking cessation counseling and adjunctive pharmacologic therapy with bupropion and nicotine replacement are key components of long-term management.
• Perform pulmonary function testing and radiographic studies every 3-6 months, as the patient's clinical condition warrants.
• Assess arterial oxygen saturation both at rest and with activity.
• Echocardiography should be considered in all patients with clinically significant dyspnea in order to screen for pulmonary artery hypertension.
• • If echocardiographic results suggest moderate-to-severe pulmonary artery hypertension, these findings should be further evaluated and confirmed with right-heart catheterization.
  • At the time of catheterization, the response to vasodilators may also be assessed.
• Patients should be vaccinated annually for influenza and should also receive the pneumococcal vaccine.

In/Out Patient Meds

• As previously discussed, corticosteroid therapy may be considered in some patients.
• Patients with an obstructive ventilatory defect on pulmonary function testing may benefit from bronchodilator therapy.
• Supplemental oxygen therapy is indicated for all patients with either resting or exertional hypoxemia. Oxygen therapy may help to prevent or slow progression of pulmonary hypertension and cor pulmonale, and it provides a mortality benefit in chronic obstructive pulmonary disease.

Deterrence/Prevention

• Effective antismoking measures can prevent PLCH. See Medscape's Smoking Resource Center.

Complications

• Spontaneous pneumothorax is a common complication (10-20%).
• PLCH is associated with an increased risk of malignancy, including Hodgkin and non-Hodgkin lymphoma, myeloproliferative disorders, and bronchogenic carcinoma.
• Pathologic fracture may occur at the site of bone lesions.
• Diabetes insipidus occurs in 10-15% of patients and indicates disease in the central nervous system.
• Pulmonary artery hypertension and cor pulmonale may develop as a result of hypoxemia and/or vascular disruption due to PLCH lesions.

Prognosis

• Prognosis varies and is related to smoking cessation. Most patients who continue to smoke experience disease progression, but for those who successfully quit smoking, the disease often stabilizes or regresses.
• Retrospective studies suggest that the following factors are associated with adverse outcomes in PLCH:
• • Extremes of age
  • Extensive cysts and honeycombing radiographically
  • Prolonged corticosteroid therapy
  • Multiorgan involvement
  • Abnormal pulmonary function, including reduced gas exchange, as measured by diffusion capacity for carbon monoxide; obstructive ventilatory defect (reduced ratio of forced expiratory volume in 1 second (FEV₁) to forced vital capacity [FVC], or FEV₁/FVC); and/or evidence of airtrapping (high residual volume/total lung capacity)
• Young men who have diabetes insipidus have the worst prognosis.
• Favorable signs include the radiographic finding of sparing of the costophrenic angles and a cellular, nonfibrotic biopsy specimen.

Patient Education

• The public must be educated about the likely etiologic role of cigarette smoking. PLCH is thought to be largely preventable through smoking cessation.
• Instruct patients to promptly report the development of hemoptysis. This symptom may indicate malignancy or superimposed bacterial/fungal infection, such as Aspergillus species infection.

MISCELLANEOUS

Section 9 of 13  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Further Reading
• Acknowledgments
• Multimedia
• References

Medical/Legal Pitfalls

• As with any uncommon medical condition, misdiagnosis or missed diagnosis can result in litigation.
• Furthermore, every treatment plan must include the clear recommendation for smoking cessation.
• Finally, given the near-universal association with cigarette smoking, tobacco company–related litigation may be an issue.

FURTHER READING

Section 10 of 13  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Further Reading
• Acknowledgments
• Multimedia
• References

See References section.

ACKNOWLEDGMENTS

Section 11 of 13  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Further Reading
• Acknowledgments
• Multimedia
• References

The authors and editors of eMedicine gratefully acknowledge the contributions of previous author, Robert S. Crausman, MD, MMS, to the development and writing of this article.

MULTIMEDIA

Section 12 of 13  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Further Reading
• Acknowledgments
• Multimedia
• References

Media file 1:  Low-power photomicrograph of a lung-tissue specimen that demonstrates the classic stellate nodule of pulmonary histiocytosis X (hematoxylin-eosin stain).
	View Full Size Image
Media type:  Photo

REFERENCES

Section 13 of 13

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Further Reading
• Acknowledgments
• Multimedia
• References

1. Gaensler EA, Carrington CB. Open biopsy for chronic diffuse infiltrative lung disease: clinical, roentgenographic, and physiological correlations in 502 patients. Ann Thorac Surg. Nov 1980;30(5):411-26. [Medline].
2. Colby TV, Lombard C. Histiocytosis X in the lung. Hum Pathol. Oct 1983;14(10):847-56. [Medline].
3. Thomeer M, Demedts M, Vandeurzen K; VRGT Working Group on Interstitial Lung Diseases. Registration of interstitial lung diseases by 20 centres of respiratory medicine in Flanders. Acta Clin Belg. May-Jun 2001;56(3):163-72. [Medline].
4. Watanabe R, Tatsumi K, Hashimoto S, Tamakoshi A, Kuriyama T,. Clinico-epidemiological features of pulmonary histiocytosis X. Intern Med. Oct 2001;40(10):998-1003. [Medline].
5. Vassallo R, Ryu JH, Schroeder DR, Decker PA, Limper AH. Clinical outcomes of pulmonary Langerhans'-cell histiocytosis in adults. N Engl J Med. Feb 14 2002;346(7):484-90. [Medline].
6. Delobbe A, Durieu J, Duhamel A, Wallaert B. Determinants of survival in pulmonary Langerhans' cell granulomatosis (histiocytosis X). Groupe d'Etude en Pathologie Interstitielle de la Société de Pathologie Thoracique du Nord. Eur Respir J. Oct 1996;9(10):2002-6. [Medline].
7. Alalawi R, Whelan T, Bajwa RS, Hodges TN. Lung transplantation and interstitial lung disease. Curr Opin Pulm Med. Sep 2005;11(5):461-6. [Medline].
8. Aricò M. Langerhans cell histiocytosis in adults: more questions than answers?. Eur J Cancer. Jul 2004;40(10):1467-73. [Medline].
9. Chaowalit N, Pellikka PA, Decker PA, Aubry MC, Krowka MJ, Ryu JH, et al. Echocardiographic and clinical characteristics of pulmonary hypertension complicating pulmonary Langerhans cell histiocytosis. Mayo Clin Proc. Oct 2004;79(10):1269-75. [Medline].
10. Crausman RS, Jennings CA, Tuder RM, Ackerson LM, Irvin CG, King TE Jr. Pulmonary histiocytosis X: pulmonary function and exercise pathophysiology. Am J Respir Crit Care Med. Jan 1996;153(1):426-35. [Medline].
11. Dacic S, Trusky C, Bakker A, Finkelstein SD, Yousem SA. Genotypic analysis of pulmonary Langerhans cell histiocytosis. Hum Pathol. Dec 2003;34(12):1345-9. [Medline].
12. King TE, Crausman RS. Pulmonary histiocytosis X. In: Fishman AP, ed. Fishman's Pulmonary Diseases and Disorders. Vol 1. 3^rd ed. New York, NY: Mc-Graw Hill; 1998:1163-70.
13. Sundar KM, Gosselin MV, Chung HL, Cahill BC. Pulmonary Langerhans cell histiocytosis: emerging concepts in pathobiology, radiology, and clinical evolution of disease. Chest. May 2003;123(5):1673-83. [Medline].
14. Tazi A. Adult pulmonary Langerhans' cell histiocytosis. Eur Respir J. Jun 2006;27(6):1272-85. [Medline].
15. Vassallo R, Ryu JH. Pulmonary Langerhans' cell histiocytosis. Clin Chest Med. Sep 2004;25(3):561-71, vii. [Medline].

Article Last Updated: Mar 3, 2008