The clarification of pathological nipple discharge is still a particular diagnostic challenge [9
]. On the one hand, this is because the imaging techniques such as mammography and sonography do not have a high diagnostic value when it comes to pathologic nipple discharge; on the other hand, this symptom cannot yet be histologically confirmed with minimal invasive techniques.
In this study intraductal epithelial proliferation could be histologically detected in 73% (24/33) of cases. In all of these 24 cases, the lesions could not be diagnosed either by clinical examination, sonography or mammography.
Galactography successfully demonstrated an intraductal lesion that could be successfully confirmed histologically in 73% (17/23) of the cases. In 33% (3/9 cases) a false positive galactography occured (histological confirmation could not be made on the postoperative specimen). We recommended a 6 month follow up for these patients (sonography).
Ductoskopy successfully demonstrated an intraductal lesion that could be histologically confirmed in 78% (18/23). Two false negative results occured from ductocopy. In both cases papillomas could be histologically diagnosed. The invasive ductal carcinomas with intraductal component as well as the DCIS were both detected by ductoscopy (Table ).
In those 3 cases of galactography that were false positive the ductoscopy showed a flat intraductal lesion in 1 case and no intraductal lesion in 2 cases. In those 5 cases of false positive ductoscopy the galactography showed an intraductal mass in 1 case and in 4 cases an unsuspicious lactiferous duct.
False passage occurred in three cases. This negatively influenced the interpretation of the study because of the small number of cases. It should be pointed out that one false passage already occurred during the galactography and the other two occurred very early in the study. We interpret this as being a result of our steep learning curve.
The challenge in the clarification of patients with pathological nipple discharge in one collective, as described in this study, (i.e. without imaging correlation from mammography or sonography) is the histological confirmation. [14
]. Open biopsy according to microdochectomy [1
], i.e. after instillation of methylene blue dye into the pathological duct only allows an indirect view of the lactiferous ducts from the exterior. In combination with galactography [2
] it is possible for the surgeon to identify the blue coloured lactiferous duct system and excise them. With this technique however, microdochectomy follows without direct visualisation of the lesion. This means that the resection volume must be relatively large and that the surgeon has no intraoperative control as to whether the intraductal proliferation, if present at all, was removed or not. If the pathologist reports an inconspicuous lactiferous duct, the question of the pathogenesis of the pathological discharge remains unknown. Four differential diagnostic possibilities can be causative here: 1) extirpation of the wrong lactiferous duct, 2) the biopsy was too superficial, i.e., the lesion lies more distal, 3) loss of the lesion during the pathological work up, 4) no intraductal proliferation which is responsible for the pathological discharge exists.
The follow-up in this particular situation is difficult. As a result of dissection of the lactiferous duct, the symptom of bloody discharge should no longer occur, assuming the correct duct has been removed. Clinical examination, sonography and mammography, along with MRI for specific questions, remain the only follow-up investigations. After non-representative ductectomy, intraductal lesions might be recognised sonographically inside a duct ectasia caused by a discharge blockage. However, a control mammography should be performed in these patients, even though the interpretation of the images can be hindered by postoperative scars.
Here the advantage of direct ductoscopic visualisation of the lesion to be removed is evident. Both the surgeon and pathologist gain information as a result of ductoscopic detection and marking of the suspect lesion. The pathologist can also be informed about the depth of the site.
Whether microdochectomy still has to be performed when a lesion has not been detected ductoscopically cannot be answered with the current data. False negative biopsies can also occur under ductoscopic visualisation. One reason for this could be a non-representative ductectomy after dilating a false lactiferous duct. Another reason for false negative biopsies is that the presence of further lesions distal to a discovered intraductal lesion cannot be excluded. This is why the galactography result showing the complete length of the lactiferous duct is important information for the surgeon.
A further advantage of ductoscopic marking is the reduction in the resection volume compared to standard procedure with methylene blue dye. According to our experience, the resection volume under ductoscopic visualisation was subjectively smaller than that of the conventional ductectomy after methylene blue instillation. An objective study of these parameters has, nevertheless, not been carried out in the available studies.
It also should be mentioned that the abdication of methylene blue dye using ductoscopy might be meaningful. Cases have been described in the literature of tissue necrosis after application of methylene blue dye[27
] which has been associated with a number of local complications due to its tissue reactive properties. Some authors have therefore suggested replacing methylene blue with an alternative dye.
Considering the future prospects of technical equipment development, it would be desirable to develop a ductoscopic minimal invasive method for clarification of pathological breast discharge. The first experiences of minimal invasive clarification of intraductal lesions solely with the ductoscope have been described in the literature [29
]. Innovative approaches such as ductoscopic-vacuum assisted biopsy removal of intraductal lesions avoiding open biopsy or instruments using the working channel of the ductoscope for cytological or histological samples [32
] are already technically realisable today. Similarly, it is also conceivable to biopsy a ductoscopically discovered lesion with classical vacuum assisted breast biopsy under combined sonographic-ductoscopic control. However, these procedures are still in the experimental stages.