Shamblin classification of carotid body tumors

This article is mainly intedend for use by medical professionals.

Carotid body tumour, also known as a chemodectoma or carotid body paraganglioma, are highly vascular tumors arising from the paraganglion cells of the carotid body. These tumors are located at the site of the carotid bifurcation.

The treatment of choice in carotid body tumors is early surgical resection.

Shamblin classification helps in predicting the prognosis and difficulties for surgical resection.

Shamblin classification

Shamblin, et al. in 1971 classified carotid body tumors in relation to the carotid vessels. In his classification

  • Group I – includes localized tumors not involving the carotid vessels.
  • Group II – tumors partially surround carotid vessels or is adherent to them.
  • Group III – defined as larger tumors encasing the carotid vessels.

As carotid body tumors become larger in size, they get more adherent to the vessels. However, Shamblin classification had some limitations because it does not reflect how deep tumor infiltrates through the wall of carotid vessels, which decides if it is possible to preserve the carotid vessels.

Modified Shamblin classification

Luna-Ortiz, et al. in 2006 proposed modifications to Shamblin classification, to improve the prediction of difficulties and complications.

They introduced a class IIIa, representing the old class III, and a class IIIb which includes tumors of any class (I, II, or III) where there is infiltration of the vessel wall and not just circumferential encasement.

Need for vascular resection and reconstruction was significantly higher among class IIIb tumors.


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