What are the next steps for a new 9 mm isodense oval density found in the left breast on MLO mammography view?

Management of a New 9 mm Isodense Oval Density in the Left Breast

The appropriate next step for a newly discovered 9 mm isodense oval density found in the left breast on MLO mammography view is to proceed with spot compression tomography in MLO projection and ultrasound evaluation as recommended in the report. 1

Diagnostic Approach for New Breast Findings

• For a newly identified breast density not seen on prior mammograms, a complete diagnostic workup is necessary to characterize the finding and determine its clinical significance 2, 1
• The diagnostic approach should include spot compression views with tomography in the MLO projection as specifically requested in the radiologist's report 1
• Ultrasound evaluation should follow if needed, as it provides complementary information about the lesion's characteristics (solid vs. cystic, margin features) 2, 1

Rationale for This Approach

• Spot compression views help separate overlapping tissues and better define the margins of the lesion, which is particularly important for densities seen on only one view 3
• Ultrasound is highly effective in characterizing mammographic abnormalities and can detect 93-100% of cancers that are occult on mammography 2
• The combined use of mammography and ultrasound provides a very high negative predictive value (>97%) when both are negative or benign 2

Significance of the Finding's Characteristics

• The finding is described as an "isodense oval density" which has the following implications:
  • Oval shape is generally considered a more favorable morphologic feature 2
  • The 9 mm size and isodense nature require further evaluation to determine if it represents a true mass or summation artifact 2, 3
  • The fact that it was not seen on prior mammography (2/16/2023) increases the importance of thorough evaluation 2

Management Algorithm Based on Further Imaging

1. Complete the recommended spot compression tomography in MLO projection

   • If the finding persists and appears as a true mass 2
   • If the finding disappears (suggesting summation artifact) 3

2. Perform breast ultrasound if the finding persists on spot compression views

   • If ultrasound shows a simple cyst: considered benign (BI-RADS 2) and can return to routine screening 2
   • If ultrasound shows a solid mass with benign features (oval shape, circumscribed margins, parallel orientation): likely BI-RADS 3 (probably benign) requiring short-interval follow-up 2
   • If ultrasound shows suspicious features: proceed to tissue sampling 2

3. Tissue sampling recommendations if indicated

   • Core needle biopsy is preferred over fine needle aspiration for solid masses 2
   • Ultrasound guidance is preferred when the lesion is visible on ultrasound 2

Important Considerations

• The location of the finding (posterior aspect of the breast at 9 o'clock position) may explain why it was not seen on the CC view, as posterior lesions can sometimes be visualized only on one projection 4
• Geographic correlation between the palpable area (if applicable) and imaging findings is essential; lack of correlation requires further evaluation 2
• Concordance between pathology, imaging, and clinical findings must be obtained if biopsy is performed 2

Common Pitfalls to Avoid

• Delaying the recommended additional imaging could lead to delayed diagnosis 1
• Relying on a single imaging modality may miss important findings, as mammography and ultrasound provide complementary information 2
• Failing to correlate the imaging finding with clinical examination when applicable 2
• Assuming a finding is benign based solely on its oval shape without complete characterization 2