Assessing a breast mass

USG · Mammography · MRI

First and second year — the floor first, then every step

Orientation, margin and posterior features — and "taller-than-wide" is judged on the RADIAL image.

Orient first

  • The strongest suspicious sonographic features are: NOT-PARALLEL orientation (taller-than-wide), an irregular or spiculated margin, marked hypoechogenicity, and posterior SHADOWING.
  • Benign-leaning features are: parallel orientation (wider-than-tall), circumscribed margin, and posterior ENHANCEMENT — none of which is sufficient alone.
  • Posterior features are a real discriminator here: shadowing suggests a desmoplastic reaction, enhancement suggests a fluid or highly cellular lesion.
  • A complicated cyst (internal echoes, no vascularity, no mural nodule) is different from a complex cystic-and-solid mass (a vascularised solid component) — the first is usually benign, the second needs tissue.

Acquire the study

  • High-frequency linear probe, 12–18 MHz; patient supine-oblique with the arm raised to flatten the breast.
  • Scan in RADIAL and ANTI-RADIAL planes, which follow the ductal anatomy — orthogonal transverse/longitudinal planes cut ducts obliquely.
  • Set the focal zone AT the lesion and gain so fat reads mid-grey before judging echogenicity.
  • Always scan the AXILLA in the same sitting.

The manoeuvre

  • Record location by CLOCK POSITION and distance from the nipple, plus depth — this is how the lesion is found again.
  • Assess ORIENTATION on the radial image: parallel or not-parallel.
  • Assess margin: circumscribed, indistinct, angular, microlobulated, or spiculated.
  • Assess echo pattern and posterior features (enhancement, shadowing, none, or combined).
  • Apply colour Doppler at low-flow settings and describe internal vascularity.
  • Measure in three planes.
  • Examine the axilla: cortical thickness, loss of the fatty hilum, and rounded shape.
  • Assign a category with its lexicon version.

What confirms it

  • A suspicious category is a conjunction of lexicon features, and the resolution is always tissue — imaging assigns probability, it does not diagnose.

What licenses you to exclude it

  • ⚠️ NORMAL IMAGING DOES NOT EXCLUDE CANCER IN A PALPABLE LUMP. Report the discordance explicitly and recommend tissue sampling; a reassuring report on a palpable mass is the classic and most damaging error in this area.
  • Dense breast tissue lowers mammographic sensitivity substantially — state the density category, because it qualifies the negative.

The classic misread

  • Judging orientation on a transverse rather than a radial image.
  • Calling a complex cystic-and-solid mass a complicated cyst without checking the solid part for flow.
  • Omitting the axilla.

Reference values

Each value carries the caveat that keeps it from being misused. Normal limits and diagnostic criteria are kept apart on purpose: a disease cut-off read as a normal range is the more dangerous mistake.

Diagnostic criteria

  • Breast mass (shape/margin) · Shape and margin lexicon

    named BI-RADS terms: oval / round / irregular, and circumscribed / obscured / microlobulated / indistinct / spiculated — these words ARE the category input

    An "irregular spiculated mass" is not improved by inventing a millimetre of spiculation. Use the lexicon words. Versioned criterion — verify against the current edition before clinical use.

    Mammography · USG

  • Breast lesion (BI-RADS) · BI-RADS 0–6 (modality lexicon first)

    0 incomplete. 1 negative. 2 benign. 3 probably benign (<2% likelihood — a specific entity, not a holding pen). 4 suspicious (4A/4B/4C). 5 highly suggestive of malignancy (≥95%). 6 known biopsy-proven malignancy. The lexicon (mass, calcification, asymmetry, distortion, MRI BPE / kinetics) is the input, not a remembered size alone

    Do not invent an edition year. A BI-RADS 3 is a specific probably-benign entity with <2% likelihood, not a holding pen for uncertainty (that is 0). Name the modality lexicon. Versioned criterion — verify against the current edition before clinical use.

    Mammography · USG · MRI

See it on real cases

Direct links to Radiopaedia — the reference article and worked cases with their images. Each opens on Radiopaedia.

Key papers

Reviews and guidelines from RSNA, ESR and related journals. Each opens at its DOI.

  1. BI-RADS v2025: Key Updates and Implications for Breast Imaging Practice ↗Minichetti P, Cereser L, Versienti E, et al. · AJR 2026ARRS · PubMed
  2. Understanding BI-RADS Category 3 ↗Fazeli S, Stepenosky J, Guirguis MS, et al. · RadioGraphics 2025RSNA · PubMed
  3. BI-RADS 5: More than Cancer ↗Dao KA, Rives AF, Quintana LM, et al. · RadioGraphics 2020RSNA · PubMed
  4. Cystic Breast Lesions: Diagnostic Approach and US Assessment ↗Lim HS, Lee HJ, Lee JS, et al. · RadioGraphics 2025RSNA · PubMed

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