Subtle Mass

Presentation and Presenting Images

( ▶ Fig. 41.1, ▶ Fig. 41.2, ▶ Fig. 41.3, ▶ Fig. 41.4)

A 76-year-old female presents for screening mammography. She was treated for right breast ductal carcinoma in situ (DCIS) 10 years ago with a lumpectomy and hormonal therapy and had a repeat lumpectomy for DCIS 2 years ago.

41.2 Key Images

( ▶ Fig. 41.5, ▶ Fig. 41.6)

41.2.1 Breast Tissue Density

There are scattered areas of fibroglandular density.

41.2.2 Imaging Findings

Central to the nipple, there are the expected postlumpectomy changes as demonstrated by architectural distortion and surgical clips. The wire on the skin surface denotes the skin incision site (just inferior to the areola). Within the lumpectomy bed, there is a new group of masses ( ▶ Fig. 41.1 and ▶ Fig. 41.2; DBT images ▶ Fig. 41.5 and ▶ Fig. 41.6) when compared to the prior mammography ( ▶ Fig. 41.3 and ▶ Fig. 41.4).

41.3 BI-RADS Classification and Action

Category 0: Mammography: Incomplete. Need additional imaging evaluation and/or prior mammograms for comparison.

41.4 Diagnostic Images

( ▶ Fig. 41.7, ▶ Fig. 41.8, ▶ Fig. 41.9, ▶ Fig. 41.10, ▶ Fig. 41.11, ▶ Fig. 41.12, ▶ Fig. 41.13)

41.4.1 Imaging Findings

The diagnostic imaging demonstrates a 1.2 × 1.1 × 1.9 cm oval mass with circumscribed margins central to the nipple within the lumpectomy bed ( ▶ Fig. 41.7, ▶ Fig. 41.8, and ▶ Fig. 41.9). The targeted ultrasound demonstrates the shadowing scar from the prior lumpectomy ( ▶ Fig. 41.10) and a mass along the lateral side of the scar. The longitudinal ultrasound image ( ▶ Fig. 41.11) demonstrates an anechoic oval mass with a thickened wall and/or a mural mass. There is no increase in vascularity (not shown). The mammographic finding is composed of two similar adjacent masses measuring 7 mm and 5 mm at greatest dimensions. These masses underwent an ultrasound-guided biopsy. The postbiopsy mammogram demonstrates the new ribbon clip (black arrow) in the center of the prior lumpectomy site ( ▶ Fig. 41.12 and ▶ Fig. 41.13).

41.5 BI-RADS Classification and Action

Category 4B: Moderate suspicion for malignancy

41.6 Differential Diagnosis

Recurrent cancer (DCIS) : The patient had a prior recurrence of DCIS, which was treated with lumpectomy alone. The patient declined radiation therapy. A new mass within the lumpectomy bed has a high suspicion of recurrence. The biopsy of this mass revealed recurrent low-grade DCIS.
Fat necrosis: Fat necrosis can have various forms and can present several years after a lumpectomy. This finding is too radiopaque (even on DBT) to represent an oil cyst. There are no associated dystrophic or rim calcifications. This lesion warrants a biopsy and not dismissal as fat necrosis.
Seroma: It is unlikely for a seroma to develop at a lumpectomy site several years after the surgery. Seromas present early after surgery and over time decrease in size.

41.7 Essential Facts

Postsurgical beds can be very complex and even subtle changes in them can be an indication of a possible recurrence of cancer.
Mammographic findings after breast-conserving therapy can be varied and present as masses (hematomas, fat necrosis, fibrosis), fluid collections (seromas, abscess), increased breast density (edema, radiation changes), skin thickening, architectural distortion, and calcifications. These findings should show evolution to stability.
Changes in the lumpectomy bed that should raise suspicion are increasing asymmetry, an enlarging mass, increasing edema or skin thickening, or development of suspicious calcifications.
Recurrence of cancer at the treatment site is generally treatment failure, that is, an inability to eradicate the original cancer.
Recurrences more than 10 years after treatment are more likely to be outside of the treated area and represent new malignancies.

41.8 Management and Digital Breast Tomosynthesis Principles

Changes in the lumpectomy site after stabilization raise concern for tumor recurrence.
Recurrences are rare within the first 2 years of treatment.
Digital breast tomosynthesis (DBT) may be helpful in resolving the differences between a lumpectomy scar and a local recurrence of cancer on imaging.
Patients who have not received radiation following breast-conserving therapy, especially for DCIS, have an increased local recurrence rate. The mammographic signs of recurrence may appear earlier than those treated with radiation.
Careful inspection should be made at the lumpectomy site on DBT for any subtle changes.

41.9 Further Reading

[1] Chansakul T, Lai KC, Slanetz PJ. The postconservation breast: part 1, Expected imaging findings. AJR Am J Roentgenol. 2012; 198(2): 321‐330 PubMed

[2] Chansakul T, Lai KC, Slanetz PJ. The postconservation breast: part 2, Imaging findings of tumor recurrence and other long-term sequelae. AJR Am J Roentgenol. 2012; 198(2): 331‐343 PubMed