Lymphangioleiomyomatosis

Lymphangioleiomyomatosis (LAM) is a rare multi-system disorder that can occur either sporadically or in association with the tuberous sclerosis complex (TSC) and is often considered a forme fruste of TSC.

Epidemiology

It almost exclusively affects women of child-bearing age 7. The estimated incidence is 1:400,000 4.

Pathology

The disease is characterised by the persistence of dilated lymphatics and interstitial proliferation of abnormal smooth muscle that in turn can obstruct venules, lymphatics, and small airways.

In the chest, there are two phases of proliferation in lymphangioleiomyomatosis. The early phase is characterised by proliferation of immature muscle cells that cover alveolar walls, bronchioles, pleura and vessels, including lymphatic routes. In the late phase there is a development of cystic spaces and wider proliferation of muscle cells throughout the lung.

Radiographic features

Lymphangioleiomyomatosis is a multi-system disorder and can affect many organs.

Bone

May show massive osteolysis with little or no periosteal reaction. Often multifocal disease

Chest

Multiple thin walled cysts throughout the lungs (usually with a uniform distribution). These are present in nearly all cases. If the cysts are small, they may be seen as diffuse coarse interstitial markings on plain film.

Additional features
  • general/radiograph
    • chylothorax: chylous pleural effusion
    • evidence of hyperinflation
    • diffuse bilateral reticulonodular densities
    • recurrent pneumothoraces in complicated cases
  • HRCT
    • thin walled cysts of variable sizes surrounded by normal lung parenchyma can be seen throughout  the lung
    • interlobular septal thickening
    • may show a dilated thoracic duct
    • haemorrhages may be seen as areas of increased attenuation
Abdomen and pelvis
Neck

Complications

Thoracic
  • recurrent pneumothorax can occur in up to 80% of cases
  • thoracic chylous collections
  • haemoptysis (occasional) 4
Abdominal
  • pelvic lymphatic obstruction

Treatment and prognosis

Despite treatment with agents such as medroxyprogesterone and tamoxifen 6, LAM tends to be progressive with most of disease severity due to pulmonary disease.

Differential diagnosis

For pulmonary manifestations, the primary differential to be considered is:

  • Langerhans cell histiocytosis (LCH)
    • tends to happen in children and young adults with a history of heavy cigarette smoking
    • mid to upper lobe distribution with preservation of costophrenic angle.
    • cysts in LCH tend to be more irregular in contour
    • has much more favourable prognosis compared with LAM
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Article Information:

rID: 7334
Section: Pathology
Tag: lungs
Synonyms or Alternate Spellings:
  • LAM
  • Lymphangiomyomatosis (LAM)
  • Lymphangioleiomyomatosis
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    Lymphangiomyomato...
    Case 1: plain film
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    Lymphangiomyomato...
    Case 1: CT
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    Case 2
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    Case 3
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    Case 4: with tuberous sclerosis
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    Case 5: with bilateral pneumothoraces
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    The initial HRCT ...
    Case 6
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