Unilateral pulmonary emphysema [MacLeod's syndrome]

This code represents a rare form of emphysema characterized by unilateral hyperlucency of a lung or a lobe, often due to obliterative bronchiolitis following a childhood infection. It results in a hypoplastic lung with reduced vascularity and air trapping, also known as Swyer-James syndrome.

Use this code when documentation clearly identifies unilateral pulmonary emphysema, MacLeod's syndrome, or Swyer-James syndrome. This diagnosis is typically supported by imaging studies (e.g., chest X-ray, CT scan) showing characteristic unilateral hyperlucency and air trapping.

• Ensure documentation specifies "unilateral" to differentiate from other forms of emphysema.
• Do not confuse with other types of emphysema (e.g., panlobular, centrilobular) unless explicitly stated as unilateral.
• Consider sequencing this code as a primary diagnosis if it is the main reason for the encounter.