Perineural spread of tumor

Last revised by Ashesh Ishwarlal Ranchod on 27 Sep 2023

Perineural spread of tumor is a form of local invasion in which primary tumors cells spread along the tissues of the nerve sheath.  It is a well-recognized phenomenon in head and neck cancers.

An important distinction has to be made between perineural invasion (PNI) and perineural spread (PNS). The former is a histological finding of tumor cell infiltration or associated with small nerves that cannot be radiologically imaged, while the latter is macroscopic tumor involvement along a nerve extending away from the primary tumor; this can be radiologically apparent. A third term, neurotropism, simply means that a tumor has an affinity for growth along nerves.

Perineural tumor spread is more frequently associated with 1,2,5:

Signs on MRI suggesting perineural tumor spread are:

  • nerve thickening
  • widening of the neural foramen
  • loss of the fat surrounding the nerve
  • abnormal perineural contrast enhancement

MRI can depict perineural tumor spread with a sensitivity of 95%, that falls to 63% regarding the entire spread's map. The presence of perineural tumor spread can be determined but for deducing its extent, cautious analysis and patterns of enhancement may be needed 9

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