Lymphangiomyomatosis and Tuberous Sclerosis
LAM

General Considerations

• Similar in pathology and x-ray appearance
• Widespread proliferation of smooth muscle in pleura, alveolar septa, bronchi, pulmonary vessels and lymphatics as well as lymph nodes, especially in posterior mediastinum and retroperitoneum
• Focal emphysema develops as result of narrowing of airways
• Thoracic duct may be obliterated
• Produce multiple small cysts with a hamartomatous proliferation of smooth muscle in their walls 

Characteristic imaging triad of:         

• Progressive, diffuse interstitial disease
• Recurrent chylous effusions and sometimes chylous ascites
• Recurrent pneumothorax 

• Tuberous sclerosis is inherited as a dominant with variable penetrance:
  • Mental defects
  • Epilepsy
  • Retinal phacoma
  • Angiomyolipomas of the kidneys
  • Rhabdomyomas of the heart
  • Intracranial calcifications
  • Sclerotic skull lesions
  • Adenoma sebaceum
  • Subungual fibromas
  • Pulmonary lymphangiomyomatosis (syn:pulmonary myomatosis)
    • Exclusively in females ages 17-47 years
    • Rare

Imaging findings

• Identical in both tuberous sclerosis and lymphangiomyomatosis and indistinguishable from pulmonary fibrosis except for decreased lung volume in fibrosis and increased lung volume in the others
• CT
• Coarse, reticular interstitial pattern
• Normal/increased lung volume
• Numerous thin-walled pulmonary cysts and honeycombing
• Various sizes/surrounded by normal lung parenchyma
• Unilateral or bilateral pleural effusions which are usually large and recurrent
• Spontaneous pneumothorax is common 

Clinically

• Progressive exertional dyspnea and cough
• Hemoptysis  

 
Lymphangiomyomatosis. Note multiple thin-walled cysts throughout both lungs.