Mediastinal lymph node enlargement

Mediastinal lymph node enlargement can occur from a wide range of pathologies and can be isolated or associated with lung pathology. Historically, a size cut-off of 10 mm short-axis diameter was used. 

Terminology

The term mediastinal lymphadenopathy implies lymph node disease and is not synonymous with mediastinal lymph node enlargement. Enlarged lymph nodes may be simply reactive as in most bacterial pneumonias, or diseased due to invasion by e.g. tuberculosis or cancer. Ideally, the term lymphadenopathy would be applied only to diseased lymph nodes however this distinction may require pathological analysis. Moreover, disease begins in normal sized lymph nodes which enlarge with disease progression.

Pathology

The spectrum of conditions that can result in mediastinal lymphadenopathy is extremely diverse and includes:

• sarcoidosis (see: pulmonary manifestations of sarcoidosis)

• primary lung cancer

• metastatic malignancies to the mediastinum from other sites

  • common

    • esophageal cancer

    • breast cancer

    • thyroid cancer

  • less common

    • malignant pleural mesothelioma

    • thymic epithelial tumor

• mediastinal lymphoma

  • primary mediastinal large B-cell lymphoma

• Kaposi sarcoma

• certain non-lymphomatous pulmonary lymphoid disorders

  • Castleman disease

  • lymphomatoid granulomatosis - pulmonary manifestations of lymphomatoid granulomatosis

  • angioimmunoblastic lymphadenopathy (AILD)

• infective etiology

  • pulmonary infection, e.g. pneumonia, pulmonary tuberculosis

    • pulmonary fungal infection

  • thoracic histoplasmosis

• occupational lung disease

  • silicosis

  • coal worker's pneumoconiosis

  • chronic beryllium lung disease

  • asbestos exposure / asbestosis ¹⁴

• smoking: maybe present in approximately 50% of heavy smokers ¹⁵

• mediastinal lymphadenopathy in interstitial lung disease

• pulmonary manifestation of rheumatoid arthritis (rare) ⁵

• scleroderma / CREST syndrome ^10,11

• related to congestive cardiac failure ^7,8,13

• thoracic amyloidosis ¹²

• medication-related, e.g. phenytoin, methotrexate ⁶

Practical points

If incidentally detected, the ACR committee white paper in 2018 suggests clinical consultation, further workup with CT-PET +/- follow up CT chest in 3-6 months if short-axis diameter over 15 mm and if there is no explicable disease ⁹. Interval size increase on follow up dictates the need for biopsy. 

See also

• lymph node enlargement

• high attenuating lymphadenopathy

• bilateral hilar lymphadenopathy

• calcified mediastinal nodes