Microdochectomy for patients with nipple discharge and the risk of associated breast cancer

Nipple discharge is one of the most common breast complaints, reported by 80% of women outside the breastfeeding period. It may result from physiological or pathological causes, including intraductal papillomas, ductal carcinoma in situ (DCIS), or invasive breast cancer (BC). This study aimed to evaluate the incidence of malignant upgrades following microdochectomy for nipple discharge and investigate the predictive value of nipple discharge characteristics, in a German population. A total of 115 patients with unilateral nipple discharge that underwent microdochectomy from 2019 to 2023 were followed up retrospectively. A standardized diagnostic algorithm was applied, including imaging (mammography, ultrasound), cytological examination of nipple discharge, and histopathological assessment of surgical specimens. We investigated the malignant upgrade after microdochectomy, and the association of different colors of nipple discharge with DCIS and invasive BC. Histopathology revealed DCIS in 7 cases (6.1%), with concomitant invasive BC in 3 cases (2.6%). Bloody nipple discharge was the most frequent symptom (85.7%) of malignant upgrade cases. However, the rate of malignancy did not significantly differ across discharge types (p = 0.442, Fisher’s exact test). All detected invasive BCs were hormone receptor positive, Human epidermal growth factor receptor 2 (HER2/neu) negative, with early-stage tumors (UICC stage IA). Preoperative cytology demonstrated limited sensitivity, with only one of four analyzed malignant cases showing suspicious findings. Microdochectomy remains a valuable diagnostic and therapeutic tool for patients with unilateral nipple discharge with unsuspicious preoperative breast imaging. The rate of newly detected BC in our study population was low. However, the preoperative identification of patients with increased risk of malignancy stays challenging. Emphasis for future research should be placed on identifying patients with the highest risk for BC e.g. bloody and clear pathologic nipple discharge.