Mammary ductoscopy is a surgical tool that allows identification of intraductal intraluminal growths and mapping of the branching patterns of the mammary ductal systems in vivo. Most successful breast endoscopists use submillimeter scopes and distend the ductal system in some way. The most obvious indication is naturally one of diagnostic and therapeutic direction of excisional biopsy for bloody or pathologic nipple
discharge. Papillomas account for a large percentage of these underlying lesions for this indication. Many of these papillomas will be present in the first 20 mm of the breast duct and can be easily identified for removal. The technology of completely removing these large central papillomas from within the limitations of a submillimeter ductoscope is evolving. Simple transillumination of the skin in the central breast can easily direct a minimal-access approach to removing these lesions. Deeper proliferative lesions causing pathologic nipple discharge are much more likely to reveal premalignant or frankly malignant changes. These lesions are almost always found within the larger ductal branches. This raises the important question of were these branches larger before the lesions arose or did they just dilate since the lesions were making fluid. Since these worrisome lesions are in the most dilated ductal branches, scoping down the largest ducts usually finds the most suspicious pathology.

Ductoscopy can be used in other ways as an adjunct to a planned surgical breast resection. Here ductoscopy allows mapping of the involved ductal tree and identification of intraluminal growths down to about 1/100 mm. This resolution is far below that of external imaging techniques such as mammography, ultrasound, and magnetic resonance imaging. Unfortunately, there is a large visual overlap in the appearance of some malignant/premalignant and benign lesions. Transscope biopsy techniques are still in their infancy, so until these are available, all intraluminal growths must be assumed to be proliferative and therefore potentially important to sample or excise. In the case of ductal carcinoma in situ or T1 breast cancers, about 60% have very small fields or zones of surrounding proliferation. The remaining 40% however seem to have a field defect within the ductal tree, leading to widespread proliferative changes at several stages of development. It is these cases that give rise to the extensive intraductal component, and multifocality or multicentricity seen in pathologic mapping of breast cancers and as secondary cancers in magnetic resonance imaging and advanced imaging cases.

Ductoscopy of a fluid-producing duct in the same quadrant of a known breast cancer will reveal a direct connection to the cancer in more than 85% of the cases and allow the surgeon to determine the presence or absence of associated proliferative changes. By mapping out these changes, using skin transillumination, the surgeon can then resect an entire ductal tree or perform a subsegment resection to incorporate the allied proliferative disease. My prospective but nonrandomized series has shown a dramatic fall in positive margin rates at initial resection (arguably because of larger resections when associated with proliferative disease) and a dramatic reduction in the local failure rate of traditional breast conservation. As more surgeons become facile with breast endoscopy, hopefully, these results can be proven even more conclusively in a prospective randomized multicenter trial.

The most important aspect of successful breast endoscopy is being able to reliably identify the correct duct and repeatedly be able to get fluid from it for successful cannulation in the operating room (OR). First, you need to develop the skill of expression of nipple fluid during your clinical exams. The La Leche League has an excellent video primer on expression of milk during lactation. The techniques it explains in detail are excellent for expressing the microliters of ductal fluid in nonlactating women with underlying proliferative breast disease. Most series report high expression of nipple fluid using such techniques in those with strong breast cancer history or high Gail model risk. A brief description of the technique is as follows: begin with careful gentle dekeratinization of the nipple papilla using a mild facial exfoliant. Next, the breast is lubricated away from the nipple with a thin moisturizing cream. The breast is then kneaded in a centripetal fashion from the edges toward the nipple as shown in Figure 5.1. Then, the dilated lactiferous sinuses in the retroareolar space are individually compressed to express milk or fluid as shown in Figure 5.2.

Next is repeatedly being able to find the offending duct between your clinic exam and the OR. You can draw a clock face on the areola and take a picture. Cannulating

the duct with a soft suture such as a 2-0 prolene can further assist in correct duct identification (Fig. 5.3). With a little practice, using a grid much as in the child’s game Battleship with letters on the x axis and numbers on the y axis, you can code position on the nipple and be able to find the ducts without the added picture step (Fig. 5.4

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