Fig. 2. Abnormalities of the ducts. A: High-grade ductal carcinoma in situ. US (left) shows a dilated duct with irregular calipers (arrows). Mammary ducts in other directions are normal. Histopathology (right, hematoxylin and eosin stain) shows cancer cells proliferating with solid and comedo patterns. B: Intraductal papilloma. US (left) shows two solid components (arrows) in the dilated ducts with steep rise and relatively high homogeneous echoes. Histopathology (right, hematoxylin and eosin stain) from core needle biopsy shows a papilloma with typical frond-like epithelium surrounding a fibrovascular core. US = ultrasound.