Extranodal extension

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Extranodal extension refers to the growth of a nodal cancer metastasis beyond the confines of the capsule of a lymph node into adjacent tissues. Less preferred synonyms include extranodal spread, extracapsular extension, or extracapsular spread.

This finding holds prognostic implications. For example, in the latest TNM staging system for most cancers of the head and neck, extranodal extension is the most significant pathological finding in a positive lymph node. For staging purposes, a regional node metastasis invading a distant organ is considered an extranodal extension and not distant metastatic disease .

Clinical presentation

Signs of extranodal extension that may be appreciated on physical examination include:

  • skin invasion
  • muscular infiltration
  • dense tethering/fixation to adjacent structures
  • neural dysfunction due to invasion

Radiographic features

CT/MRI

The appearance of extranodal extension includes:

  • indistinct nodal margins
  • irregular nodal capsular enhancement
  • soft tissue infiltration into adjacent fat or muscle