The aim of this study was to assess retrospectively the ability of ^99mTc-(V)DMSA and ^99mTc-MIBI to recognize benign breast lesions such as HUT and AM, with elevated proliferative activity at different ER status, which have different probabilities to progress into invasive tumors.

Twenty-one patients with histologically confirmed HUT and/or AM were submitted preoperatively to (V)DMSA and/or MIBI scintimammography, 10 min and 60 min after administration of 925–1100 MBq each radiotracer. Immunohistochemical staining was performed using the avidin–biotin method to determine Ki-67 and ER positivity. Lesion to background ratios (L/B) were calculated and compared (t test) with Ki-67 and ER values in HUT and AM with both tracers (Ki-67 >3% and ER >15% were considered positive).

Histology demonstrated HUT in 11 patients and AM in 10 patients. Mean L/B ratios for (V)DMSA and MIBI in HUT and AM were 1.71 ± 0.44 (range 1.0–2.6), 1.2 ± 0.23 (range 1.0–1.6), 1.1 ± 0.06 (range 1.0–1.2) and 1.15 ± 0.05 (range 1.05–1.2), respectively. Ki-67 for HUT ranged from 1 to 20% (mean ± standard deviation [SD], 6.25 ± 5.7) and ER from 0 to 90% (mean ± SD, 43.8 ± 5.7). Ki-67 for AM ranged from 1 to 15% (mean ± SD, 4.83 ± 4.7). In patients with HUT and Ki-67 <3% the mean L/B (V)DMSA ratio was 1.13 ± 0.10, while in those with HUT and Ki-67 >3% it was 1.89 ± 0.35 (P = 0.0012). In patients with HUT and ER <15% the mean (V)DMSA L/B ratio was 1.66 ± 0.47, while in ER >15% it was 1.73 ± 0.43 (not statistically different). L/B MIBI ratios were not significantly different in the groups with higher or lower Ki-67 and ER values in patients with HUT (1.48 ± 0.45 for Ki-67 <3% and 1.25 ± 0.15 for Ki-67 >3%). AM did not show any statistical difference between L/B (V)DMSA and MIBI in the groups with higher and lower Ki-67 and ER expression.

(V)DMSA uptake in HUT seems to be related to Ki-67 activity and could be a useful indicator of the probability of these lesions to progress to atypical hyperplasia, ductal carcinoma in situ or invasive tumors.