Which patients require or can skip biopsy for breast clustered microcysts? Predictive findings of breast cancer and mucocele-like tumor

Background In order to determine the patients who require biopsy for breast clustered microcysts, we retrospectively investigated cases of clustered microcysts that were detected by ultrasonography (US) examinations. Methods We investigated 52 patients in whom clustered microcysts were detected by US and who underwent biopsy at our institution between January 2011 and March 2014. These patients were divided into two groups according to histopathological findings: those with invasive carcinoma (IC), ductal carcinoma in situ (DCIS), or mucocele-like tumor (MLT) (Group 1), and those with benign lesions (Group 2). Mammography (MG) and magnetic resonance imaging (MRI) findings were assessed in these two groups. Results There were 12 patients in Group 1 (IC:2, DCIS:6, and MLT:4) and 40 patients in Group 2. In 51 of the 52 patients, MG was performed before biopsy. Since 11 of 12 patients in Group 1 exhibited MG findings (mass, focal asymmetry, coarse heterogeneous calcifications and fine pleomorphic calcifications) at the same site as the clustered microcysts, and that MG findings had a significant probability of detecting clustered microcysts categorized into Group 1 with a sensitivity of 91.7 % and negative predictive value (NPV) of 96.8 % ( p