Adenomyoepithelioma of the breast with malignant transformation and repeated local recurrence: A case report

Figure 1 Imaging and pathology findings at the time of the initial surgery. A: The mammogram showed an oval, smooth, well-defined, isodense mass in the upper right breast (white arrow); B: Ultrasonography showed a well-defined mass with cystic changes, measuring up to 16 mm, at the 2 o’clock position of the right breast; C: The tumor was a cystic lesion, and the cystic wall had nodules or irregular thickening (× 65 magnification); D: Round or spindle-shaped myoepithelium proliferating in and around the gland ducts was observed. High mitotic counts were prominent in the myoepithelial component (× 100 magnification).

Figure 2 Imaging and pathology findings at first recurrence. A: Ultrasonography showed a well-defined, oval, low-isoechoic mass; B: The tumor was a cystic lesion, and the cystic wall had nodules or irregular thickening. The cysts contained mucus (× 32 magnification); C and D: Epithelium with squamous metaplasia growing into the lumenal side (C: × 100 magnification, lumen side) and (D: × 100, membrane side). Dense growth of spindle-shaped myoepithelium is found on the side of the membrane. The myoepithelium spreads underneath the existing glandular epithelium. Tumor cells show prominent nuclear atypia and high mitotic counts; E: The Ki 67 hot spot is 57.1% (× 100 magnification, Ki67).

Figure 3 Imaging and pathology findings at the 2^nd recurrence. A: Ultrasonography shows a series of masses of up to 27 mm located on the right side of the previous surgical wound; B: Enhanced breast magnetic resonance imaging showed multiple masses up to 25 mm in the right inner-upper area (white arrow). The masses were cystic with thick walls, similar to the previous tumor, and were diagnosed as recurrent adenomyoepithelioma. Two 7-mm nodules were also found within the pectoralis major muscle (arrowhead); C: The tumor was a cystic lesion, and the cystic wall had nodules or irregular thickening. The cyst contained mucus (× 3 magnification); D: Biphasic proliferation of both inner epithelium with squamous metaplasia and outer spindle-shaped myoepithelium was seen (× 100 magnification). Both cell types showed prominent nuclear atypia and high mitotic counts that were especially prominent in the epithelial component. The histological findings were the same as those of the previous surgery; E: The tumor cells invaded the extramammary adipose tissue.