## 4 Discussion
Figure 4: A 79-year-old woman with a pathological diagnosis of ductal carcinoma in situ. (**A**) Magnified galactogram which shows obstruction in the duct and microdefects with a moth-eaten appearance (arrows), which was included in the Galactogram Image Classification System (GICS) 5 category: high suspicion of malignancy. (**B**) Magnified sonogram showing a micronodular pattern and badly-defined duct wall (arrows), with hyperechoic foci which correspond to the contrast dye injected. Figure 5: A 58-year-old woman with a pathological diagnosis of ductal carcinoma in situ. **(A)** Magnified galactogram which shows microdefects with a moth-eaten appearance (arrows), which was included in the GICS 5 category: high suspicion of malignance. **(B)** Sonogram showing a solid hyper-echoic pattern with badly-defined duct wall (thick arrows), and intraductal hyperechoic content (thin arrows), which correspond to the contrast dye injected. As for the GL, inconveniences were also found, as it is a minimally invasive technique, the procedure takes some time, there could be a failure in the canalization of the secretory duct, and it does not allow for differentiating between benign and malignant lesions [3; 6; 7; 17]. In addition, many studies [16; 17; 18] point out that MRI is superior to the GL for the evaluation of PND. However, MRI is more expensive than the GL, and the examination time is even longer [9]. Likewise, MRI cannot be utilized with women who suffer from claustrophobia and its contraindications must be considered, such as metallic implants, allergy to the contrast dye, or renal insufficiency. Lastly, it should be pointed out that MRI is not included among the recommendations for the evaluation of PND patients [1; 11; 12]. Additionally, mammary ductoscopy is a technology that allows for the direct visualization and biopsy examination of the mammary ductal abnormalities [26; 27]. Furthermore, recent studies [28; 29] have reported that digital breast tomosynthesis-GL may become an important diagnostic step for managing PND. In a recent study [20], the diagnostic potential of a second-look US after a GL for borderline and malignant lesions was evidenced. In the present study, the SGL combined with the GL improved the diagnostic efficiency, especially with borderline and malignant lesions. In addition, the SGL allows performing the CNB. In this study, the histopathological results of the CNB did not correlate with the final pathological diagnosis, perhaps because the intraductal lesions were very small. Additionally, it has been reported that the papillary neoplasia diagnosis of the breast can be challenging, especially if only the equipment for a CNB is available [30]. Therefore, the collaboration between clinicians, radiologists, and pathologists is of great importance for optimizing the efficiency of diagnosis. Our study also had limitations, as it is a retrospective study and the sample was small. In addition, experience is required for the interpretation of the findings from the GL and the SGL as well. The galactograms were categorized with the GICS, which has been reported to have a good to very good inter- and intra-observer agreement [31]. It should also be taken into account that the SGL is an operator-dependent examination. Nevertheless, we consider that in this study, the combination of GL with SGL was fundamental for the diagnosis of PND. We thus recommend the diagnostic algorithm described in the present study for the management of PND patients.