Imaging and Histopathologic Features of BI-RADS 3 Lesions Upgraded during Imaging Surveillance

Abstract

To evaluate imaging and histopathologic differences between screen-detected benign and malignant upgraded lesions initially assessed as BI-RADS 3 at diagnostic evaluation. An IRB approved retrospective review of the mammography data base from January 1, 2004 to December 31, 2008 identified 1,188 (1.07%) of 110,776 screening examinations assessed as BI-RADS 3 following diagnostic evaluation at our academic center (staffed by breast specialists) or our outpatient center (staffed by general radiologists), 1,017 with at least 24 months follow-up or biopsy. Sixty (5.9%) BI-RADS 3 lesions were upgraded to BI-RADS 4 or 5 during imaging surveillance (study population). Prospective reports, patient demographics, and clinical outcomes were abstracted from the longitudinal medical record. Mean patient age was 54.1 years (range 35-85). Lesions consisted of 7 masses, 12 focal asymmetries and 41 calcifications. Fifteen (25%) of 60 lesions upgraded from initial BI-RADS 3 assessment were malignant (1.47% of total; 15/1,017 BI-RADS 3 studies). Malignancy rates by upgraded lesion type showed no significant difference: Thirty-three (73.3%) of 45 benign upgraded lesions were calcifications compared to 8 (53.3%) of 15 malignant upgraded lesions (p = 0.202). Twelve (26.7%) of 45 benign upgraded lesions were masses or focal asymmetries, compared to 7 (46.7%) of 15 upgraded malignant lesions (p = 0.202). Six (85.7%) of 7 malignant upgraded masses/focal asymmetries had no US correlate at initial BI-RADS 3 assessment compared to 7 (58.3%) of 12 benign upgraded masses/focal asymmetries (p = 0.33). Breast-imaging specialists interpreted 21 studies, 3 (14.3%) malignant; general radiologists interpreted 39 studies, 12 (30.8%) malignant (p = 0.218). There was no significant difference in malignancy rate among different types of upgraded mammographic lesions, nor depending on subspecialty interpretation versus nonsubspecialist interpretation. Although calcifications made up a majority of upgraded lesions, most were benign, suggesting that decreased surveillance of calcifications may be appropriate.

Probably Benign Findings: Probably the Emperor with No Clothes

“…Notably, calcifications comprised the majority of lesions referred to as category 3, however, 80% (33/41) of the suspicious calcifications were benign. A lower percentage of masses and focal asymmetries were benign (63%; 12/19) . Similarly in Sickles’ study, calcifications only comprised 2/17 malignancies which arose from probably benign lesions .…”

“…In this study, Michaels et al. demonstrated half (4/8) of the malignant calcifications returned invasive ductal carcinoma on histopathology, and these four cases were diagnosed at 12–24 months follow‐up . For microcalcifications, the current recommended follow‐up interval may be extended to reflect their short‐term statistically benign course.…”

“…In Michaels et al. study, it is reassuring that only three malignancies diagnosed at the 6 month follow‐up for microcalcifications were DCIS rather than invasive cancer . Given the low rate of malignancy among BI‐RADS 3 lesions, a recommendation for 1 year follow‐up with emphasis on adherence may be alternative to the current recommended 6 month interval .…”

“…In the current issue of The Breast Journal issue, Michaels et al. investigated the natural history of lesions upgraded to BI‐RADS 4 and 5, and this may permit further refinement of the management strategy for probably benign findings. Consistent with prior studies, Michaels et al.…”

Surveillance of BIRADS 3 lesions

“…To the Editor: I read with great interest the article by Michaels et al 1 addressing the imaging and histopathologic features of BIRADS 3 lesions upgraded during imaging surveillance.…”