Adult pulmonary Langerhans cell histiocytosis

This code identifies a rare interstitial lung disease characterized by the proliferation of Langerhans cells within the pulmonary parenchyma. It primarily affects adult smokers and can lead to cystic lung changes, emphysema, and progressive respiratory failure. The condition is a form of Langerhans cell histiocytosis (LCH) localized to the lungs.

Assign this code for documented cases of adult pulmonary Langerhans cell histiocytosis confirmed by lung biopsy or characteristic imaging findings in a symptomatic patient. This code is appropriate when the disease is confined to the lungs without evidence of multi-system involvement. Documentation should clearly indicate "adult" and "pulmonary" involvement.

• Ensure documentation specifies "adult" to differentiate from pediatric forms of LCH, which may have different ICD-9 codes.
• Do not use this code for multi-system Langerhans cell histiocytosis; a more general LCH code would be appropriate in such cases.
• Code any associated complications, such as pneumothorax or respiratory failure, separately.