Ductal carcinoma in situ
- Definition: Neoplastic epithelial proliferation confined to the ductal-lobular system; no basement membrane invasion.
- Grading: Low, Intermediate, High (nuclear grade).
- Imaging:
- Mammography: Microcalcifications (70-80% of cases). Morphology: Pleomorphic, fine linear branching (casting), or crushed stone.
- MRI: Non-mass enhancement (segmental or ductal distribution).
- Exam Tip: High-grade DCIS often associated with "comedo necrosis" (central necrosis within ducts).
