The patient was a 13-year-old Chinese girl who presented to the doctor with spontaneous bloody discharge of the left nipple for more than 20 days. Her personal history was remarkable for breast development for one and a half years, and menarche more than one month ago. Moreover, she sustained use of growth hormone due to short stature in the past six months. On clinical examination, a central area palpable mass at 3 o’ clock of his left breast was found with clear boundaries and measured approximately 2.5×1.5cm. Bloody discharge could be seen by squeezing the mass from one single hole. Laboratory data, including blood count, chemistry and hormone levels, were within the normal limits. Ultrasound sonography showed an intracystic mass under the left nipple, measuring 23.6 × 15.8 × 8.7 mm in diameter (Fig. 1A). The mass seemed to be located within the lumen of a dilated duct with the width of 2.2mm. The surrounding of mass was noted on color Doppler imaging. Fiberoptic ductoscopy showed a lobulated neoplasm at the opening of the grade II milk duct, which protruded into the lumen and did not completely block the duct (Fig. 1B). There was capillary hyperplasia on the surface with rupture and bleeding. There was no other neoplasm in the proximal and distal duct of which the wall was smooth.
Surgeons first considered to be a benign intraductal papilloma, and carried out removal the mass and part of the breast duct connected to it by methylene blue staining (Fig. 1C). On gross examination, the cut surface showed clear boundaries and coatings, and a thin cystic cavity is formed around it, measuring approximately 18 × 15 mm in diameter (Fig. 1D).
Microscopically, a dilated duct was found in the excised tissue, of which ductal epithelium proliferated to form cystic changes. Fibroadenomatous polypoid structures were seen within the cystic lumens (Fig. 2A). The neoplasm consisted of multiple polypoid papillary lesion and leaf-like fashion. Characteristic delicate fibrovascular stalks found in the polypoid papillary lesion was IP. The leaf-like fashion with a hypocellular and prominent myxoid stroma protruded into the lumens of the ducts, reminiscent of IF. Mitotic figures were very rarely seen. Overall, the main features were of IP and IF, and two features were in equal proportion (Fig. 2B), with cystic changes of ductal epithelium hyperplasia. The patient was discharged 2 days after surgery without any postoperative complications. So far, the patient has been routinely followed up for more than 15 months after surgery, and no recurrence has been found.