Ipsilateral microcalcifications after breast-conserving surgery: is it possible to differentiate benign from malignant calcifications?

To analyse stereotactic biopsies of microcalcifications in patients with previous ipsilateral breast-conserving surgery (BCS) to identify the positivity rate, assess for an association between the patient's primary cancer or mammographic appearances of the microcalcifications, and the risk of recurrence.Relevant patients from 2018-2020 were identified via a retrospective review of the prospectively maintained radiological procedure database. Clinicopathological features of the patients' primary tumour and new calcifications were obtained from the hospital electronic patient record system and the national integrated medical imaging system.Thirty-one percent of recurrences post-ipsilateral BCS presented as isolated microcalcifications on mammography. Fifty-three percent of patients undergoing stereotactic biopsy of ipsilateral calcifications had recurrence. A positive margin status was associated with new or recurrent malignancy. There was no significant correlation between oestrogen-receptor status, sentinel lymph node status, adjuvant radiotherapy or chemotherapy and the risk of recurrence. Calcifications within the tumour bed were more likely to be benign while calcifications within the same quadrant but remote from the tumour bed were more likely malignant. All coarse calcifications were benign while 67% of fine linear/fine linear branching and 89% of fine pleomorphic calcifications were malignant.Increased time since diagnosis, positive margin status, fine pleomorphic and fine linear calcifications in the same quadrant as the tumour bed were associated with malignancy. Patients with coarse calcifications and calcifications within the tumour bed may avoid stereotactic biopsy and undergo short-interval surveillance.