Utility and Outcomes of Imaging Evaluation for Palpable Lumps in the Postmastectomy Patient

OBJECTIVE. The objective of our study was to assess the utility of targeted breast ultrasound and mammography in evaluating palpable lumps in the mastectomy bed. MATERIALS AND METHODS. This retrospective study identified postmastectomy patients who presented for initial imaging evaluation of palpable lumps between January 2009 and December 2015. Clinical, imaging, and pathology results were reviewed. Surgical reconstruction type and percutaneous sampling data were collected. Patients were excluded if they had known malignancy at imaging presentation, if the palpable lump was not at the mastectomy site, or if there was less than 1 year clinical or imaging follow-up in the absence of biopsy. Each palpable site was assigned as a case, and analyses were performed at the case level. RESULTS. Among the 101 patients with a history of prophylactic or therapeutic mastectomy who presented during the study period, 118 palpable cases met the inclusion criteria. All 118 cases were evaluated with ultrasound and 43 with mammography. Among the 75 cases evaluated with ultrasound alone, nine cancers were detected. Among the 43 cases evaluated with both ultrasound and mammography, three cancers were sonographically detected, of which two were mammographically visible and one was mammographically occult. There were two false-negative ultrasound cases; both underwent sampling because of the level of clinical suspicion. In total, 14 palpable lumps in 12 patients were malignant, and 104 palpable lumps in 89 patients were nonmalignant. Targeted ultrasound yielded a negative predictive value (NPV) of 97% and a positive predictive value 2 of 27%. CONCLUSION. Our data suggest that targeted breast ultrasound, with its high NPV, should be the initial imaging test of choice for palpable lumps after mastectomy. Mammography yielded no additional cancers but was helpful in confirming benign diagnoses. The two false-negative ultrasound cases support palpation-guided sampling for imaging-occult and clinically suspicious palpable lumps.