The diagnostic value of nipple discharge cytology in 618 consecutive patients

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.

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.

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%)).

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.