Disruption of the Anterior Borders of the Mammary Gland on Ultrasound Does Not Always Indicate the Presence of Invasive Breast Cancer Components: A Case Report.

Disruption of the anterior borders of the mammary gland on ultrasound usually indicates the presence of invasive breast cancer components in the tumor. A 60-year-old woman was referred to our hospital for a detailed examination of an abnormality on screening mammography. Mammography showed distortion of the mammary gland and no definite masses in the left breast. Ultrasound also did not depict any masses but showed low echoes with indistinct margins and disruption of the anterior borders of the mammary gland. MRI of the target lesion showed low signals on T1-weighted images and very weak high signals on fat-suppressed T2-weighted images, with initial slow enhancement followed by a plateau pattern on dynamic studies. These imaging findings led us to perform a vacuum-assisted biopsy of the target areas, which pathologically showed non-invasive cancer cells growing in a cribriform fashion. Despite the lack of invasive components in the biopsy specimen, the patient underwent breast-conserving surgery and sentinel node biopsy to avoid undertreatment. Frozen section confirmed no lymph node metastasis and negative surgical margins. Postoperative pathological examination showed that the breast cancer had sparse ductal carcinoma in situ growing in cribriform and solid patterns, along with focal depression of the background fibrous stroma edges at the presumed disruption areas of the mammary gland anterior borders. The patient recovered uneventfully, has received adjuvant radiotherapy to the conserved breast, and has been well on endocrine therapy for four months. Diagnostic physicians should note that disruption of the anterior borders of the mammary gland on ultrasound does not always indicate the presence of invasive breast cancer components.