How are breast nodules classified on ultrasonography?

Updated: Feb 01, 2017
  • Author: Paul R Fisher, MD; Chief Editor: Eugene C Lin, MD  more...
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In a landmark study, Stavros et al established US criteria for characterizing solid breast masses. [48] This work was facilitated by evolving technical improvements in US equipment that provided better resolution and images. They demonstrated that US may be used to accurately classify some solid lesions as benign, allowing follow-up with imaging rather than biopsy. They used high-resolution transducers, which were state-of-the-art at that time, and performed examinations in both radial and antiradial planes. The investigators also focused on the evaluation of suspected areas in the transverse and longitudinal planes.

Stavros et al proposed a US scheme for prospectively classifying breast nodules into 1 of 3 categories [48] :

  • Benign

  • Indeterminate

  • Malignant

To be classified as benign, a nodule had to have no malignant characteristics. In addition, 1 of the following 3 combinations of benign characteristics had to be demonstrated:

  • Intense uniform hyperechogenicity

  • Ellipsoid or wider-than-tall (parallel) orientation, along with a thin, echogenic capsule

  • 2 or 3 gentle lobulations and a thin, echogenic capsule

A nodule was classified as indeterminate by default if it had no malignant characteristics and none of the 3 benign characteristic combinations listed above.

To be classified as malignant, a mass needed to have any of the following characteristics:

  • Spiculated contour

  • Taller-than-wide (not parallel) orientation

  • Angular margins

  • Marked hypoechogenicity

  • Posterior acoustic shadowing

  • Punctate calcifications

  • Duct extension

  • Branch pattern

  • Microlobulation

Of the 424 lesions that Stavros et al prospectively classified as benign by means of US, only 2 were found to be malignant at biopsy, resulting in a negative predictive value of 99.5% in a population with a cancer prevalence of 16.7%. [48] Of the 125 lesions found to be malignant at biopsy, 123 were classified as malignant or indeterminate with US, yielding a sensitivity of 98.4%. Biopsy is indicated for nodules that are classified on US as either malignant or indeterminate.

Skaane et al found that US could distinguish fibroadenomas from invasive ductal carcinoma. [49] Others who have studied the characteristics of benign and malignant masses by US examination include Zonderland et al and Rahbar et al. [50, 40]

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