What is the radiographic classification of Mycobacterium avium complex (MAC) lung disease?

From the Guidelines

Mycobacterium avium complex (MAC) lung disease is radiographically classified into two main forms: fibrocavitary disease and nodular/bronchiectatic disease. The fibrocavitary form typically presents with cavitary lesions predominantly in the upper lobes, resembling tuberculosis, and is more common in older men with underlying lung conditions like COPD or prior TB 1. The nodular/bronchiectatic form, also known as Lady Windermere syndrome, shows multiple small nodules and cylindrical bronchiectasis primarily in the middle lobe and lingula, and is more common in non-smoking middle-aged or elderly women without underlying lung disease 1. Some patients may present with a mixed pattern showing features of both forms.

Key Characteristics of Each Form

• Fibrocavitary disease:
  • Cavitary lesions in the upper lobes
  • Resembles tuberculosis
  • More common in older men with underlying lung conditions
• Nodular/bronchiectatic disease (Lady Windermere syndrome):
  • Multiple small nodules and cylindrical bronchiectasis
  • Primarily in the middle lobe and lingula
  • More common in non-smoking middle-aged or elderly women without underlying lung disease High-resolution computed tomography (HRCT) is the preferred imaging modality for diagnosis and classification as it can detect subtle bronchiectasis and small nodules that may not be visible on plain chest radiographs 1. These radiographic patterns are important for diagnosis, treatment planning, and monitoring disease progression, as the fibrocavitary form generally progresses more rapidly and may require more aggressive treatment than the nodular/bronchiectatic form 1.

From the Research

Radiographic Classification of MAC Lung Disease

The radiographic classification of Mycobacterium avium complex (MAC) lung disease can be categorized into several types, including:

• Fibrocavitary disease: characterized by upper lobe cavitation, similar to pulmonary tuberculosis 2, 3, 4
• Nodular bronchiectatic disease: characterized by bronchiectasis and centrilobular nodules, often involving the right middle lobe and left lingual segment 2, 3, 4, 5
• Hypersensitivity-like disease: a rare type of MAC lung disease 5
• Disseminated disease: a rare type of MAC lung disease 5

Key Features of Each Type

• Fibrocavitary disease:
  • Often occurs in males 3
  • Associated with upper lobe cavitation 2, 3, 4
  • Similar to pulmonary tuberculosis 2, 3
• Nodular bronchiectatic disease:
  • Often occurs in females, particularly nonsmoking, immunocompetent, middle-aged women 3, 5
  • Characterized by bronchiectasis and centrilobular nodules 2, 3, 4
  • Often involves the right middle lobe and left lingual segment 5
  • Common CT manifestations include nodules just beneath the pleura, consolidation including bronchiectasis, and lung volume shrinkage 5

Comparison with Other Mycobacterial Infections

• MAC lung disease can be distinguished from Mycobacterium xenopi lung disease, which is more commonly associated with a fibrocavitary radiologic pattern and random nodules or consolidation and/or ground-glass opacities 4