Adult pulmonary Langerhans cell histiocytosis

This code identifies a rare interstitial lung disease characterized by the proliferation of Langerhans cells within the pulmonary parenchyma of adults. It is a form of histiocytosis that primarily affects the lungs, leading to the formation of granulomas and cysts. The condition can result in progressive lung damage and respiratory compromise.

Apply this code when documentation clearly indicates a diagnosis of adult pulmonary Langerhans cell histiocytosis. This diagnosis is typically confirmed through lung biopsy showing characteristic Langerhans cell infiltrates, often in conjunction with imaging findings such as cystic lesions or stellate nodules. Use this code for established diagnoses, not for suspected cases.

• Ensure documentation specifies "adult" to differentiate from pediatric forms of Langerhans cell histiocytosis.
• Do not confuse with other interstitial lung diseases; look for explicit mention of Langerhans cells.
• Consider sequencing this code as a primary diagnosis when it is the main reason for the encounter, or as a secondary diagnosis if it is a comorbidity affecting treatment.