Utility of Diagnostic Mammography as the Primary Imaging Modality for Palpable Lumps in Women With Almost Entirely Fatty Breasts

OBJECTIVE. The purpose of this study was to assess the performance of diagnostic mammography alone for evaluation of palpable symptoms in women with almost entirely fatty breast composition. MATERIALS AND METHODS. All diagnostic mammograms performed for palpable symptoms in women who had been assigned a breast density of "almost entirely fatty" over an 8-year period (2009-2017) at an academic breast center were retrospectively identified. Each symptomatic breast was considered a separate case and analyses were performed at the case level. Clinical, imaging, and pathologic results were reviewed. Descriptive statistics and 2 × 2 contingency table analyses were performed. RESULTS. The study cohort included 323 cases evaluated with mammography. Of these, 294 (91%) had undergone targeted ultrasound. At mammography, 240 (74%) had no correlate to the palpable lump; 38 (12%), a benign correlate; and 45 (14%), a suspicious correlate. Three cases had incidental suspicious mammographic findings, for a total of 48 positive mammography cases. Twenty-seven (8%) cases were malignant. Mammography alone detected all but one cancer, which was detected by ultrasound. In retrospect, the woman from whom this single false-negative mammogram was obtained did not have almost entirely fatty breast density. Mammography alone yielded a negative predictive value of 99.6%, percentage of diagnostic examinations recommended for biopsy that resulted in a tissue diagnosis of malignancy within 1 year of 54%, sensitivity of 96%, and specificity of 93%. Adjunct ultrasound contributed to 11 false-positives but also identified benign correlates in eight cases with no mammographic finding. CONCLUSION. In patients with almost entirely fatty breast tissue presenting with palpable symptoms, mammography alone had a high sensitivity and specificity. Our results support that mammography alone may be sufficient for evaluation of palpable symptoms in these women as long as density criteria are strictly applied.