Mammographic Appearance of the Breast after Breast Conservation Therapy

Expected mammographic changes in the breast 6 months after completion of radiation therapy as part of breast conservation therapy include:
Diffuse changes from radiation

• Generalized skin thickening: intra- and extra-cellular edema from radiation. Maximal at 6 months and either stable or decreasing on subsequent mammograms (may take years).
• Increased breast markings: Engorged breast lymphatics. Usually gone by 1 year.
• Overall increased breast density: Due to skin thickening and suboptimal compression of the treated breast.

Localized changes at the excisional biopsy site:

• Mass or vague density at operative site: From edema, hematoma, or seroma. Can assume to be post-surgical if there is histological proof of complete resection.
• Architectural distortion: From surgical damage. Can assume to be post-surgical if there is histological proof of complete resection. Should decrease in size as time goes on.
• Early fat necrosis: Most commonly lipid cyst, but can also see macroscopic (benign) calcifications. Benign-appearing microcalcifications that occur at the lumpectomy site within three years after treatment may be followed up.

References

• Dershaw DD, Shank B, Reisinger S. Mammographic findings after breast cancer treatment with local excision and definitive irradiation. Radiology. 1987 Aug;164(2):455-61.
• Vora SA, Wazer DE, Homer MJ. Management of microcalcifications that develop at the lumpectomy site after breast-conserving therapy. Radiology. 1997 Jun;203(3):667-71.