Aim: Preoperative stratification of patients presenting with nipple discharge (ND) according to malignancy risk has proven difficult. Nevertheless, cytological examination is considered to be a diagnostic aid. The aim of this study was to determine its complementary value in clinical decision-making in patients presenting with ND.
Methods: We retrospectively collected data on macroscopic ND colour, ND cytology, physical examination, mammography, ultrasound and fine-needle aspiration cytology results. On ND cytology, benign diagnoses were considered negative, whereas suspicious and malignant diagnoses were considered positive for malignancy.
Results: From 1992 to 2006, 618 patients had an ND smear, of those 163 patients had a biopsy. Sensitivity and specificity were 16.7% and 66.1%, respectively. These values were lower when ND was bloody than when ND was non-bloody (p=0.66 and p<0.05 for sensitivity and specificity, respectively). When macroscopically defining bloody ND as positive and non-bloody ND as negative, macroscopic ND colour examination had a remarkably higher sensitivity (60.6 vs. 18.2%, p<0.001) and only a slightly lower specificity (53.6 vs. 65.0%, p=0.07) when compared to cytological ND examination. Only 1 malignant lesion was designated positive solely by ND cytology (unique sensitivity (95% CI), 2.8% (0.0-8.4%)) and 3 lesions were correctly classified as negative by ND cytology (unique specificity (95% CI), 1.6%, 0.0-3.7%)).
Conclusion: Nipple discharge cytology has little complementary diagnostic value. Therefore, its routine use for detection of ND-related breast pathology should be reconsidered carefully. Nipple discharge cytology may redirect patient management well in some cases, but it may confuse work-up in the majority.