Pulmonary langerhans cell histiocytosis

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[edit] Discussion of Pulmonary langerhans cell histiocytosis

  • Langerhans cell histiocytosis (LCH) was formerly known by as histiocytosis X and eosinophilic granuloma.
  • Although the etiology of LCH is unknown, theories include viral infection, antigen exposure, and somatic mutation.

  • Pulmonary LCH refers to LCH isolated to the respiratory system (notably the lungs).
  • Found almost exclusively in cigarette smokers.
  • Presents in the third to fourth decade of life.
  • Most common clinical symptoms include dyspnea, cough, and fatigue.
  • Decrease in carbon monoxide diffusing capacity is present in up to 90% of patients.

  • For most patients, symptom stabilization occurs with smoking cessation alone.
  • Corticosteroid therapy caused disease stabilization in some studies.

  • Patients with pulmonary LCH have variable and uncertain clinical courses.
    • Adults with the disease have decreased overall long-term survival compared to those without the disease.
    • Mortality from pulmonary LCH can occur due to pulmonary hypertension or respiratory failure.
    • There is no known link between relapse of disease and continuation of smoking or between regression of disease and cessation of smoking.

[edit] Imaging Findings for Pulmonary langerhans cell histiocytosis

  • Radiologic findings of pulmonary LCH vary depending on the stage of the disease at diagnosis.
  • Middle and upper lung zones are involved to a greater extent than the lung bases.
  • Diffuse bilateral ill-defined nodules will be seen in early stages. It is thought that these nodules undergo cystic degeneration as the disease progresses, and so a reticular pattern begins to predominate on chest radiographs as the numerous cystic walls are superimposed on one another.
  • The cysts and residual parenchyma can undergo fibrosis over time and eventually lead to changes of honeycombing.

  • Diagnosis can be easily made with high-resolution CT by showing both ill-defined nodules and cysts in a heavy smoker.
  • Diagnostic accuracy of high-resolution CT falls short when only nodules or cysts alone are present.

  • Differential diagnosis of primarily cystic lung disease includes predominantly cystic pulmonary LCH, lymphangiomyomatosis, emphysema, and bronchiectasis.
    • Cysts in LCH are often variable in size and wall thickness.
    • Cysts of lymphangiomyomatosis can resemble those of pulmonary LCH, but they occur diffusely throughout the lungs and affect women almost exclusively.
    • Cystic cavities of emphysema represent foci of destroyed parenchyma and lack definable walls.
    • Cystlike bronchial dilatation seen in bronchiectasis can be distinguished by the communicating branching pattern seen on contiguous CT images.

[edit] Images

Patient #1

[edit] See Also

[edit] External Links

[edit] References for Pulmonary langerhans cell histiocytosis