Ductal Carcinoma in Situ of the Breast

Low Grade Ductal Carcinoma In Situ

Dilated ducts completely filled with uniform cells
- No streaming of cells
- No cells with elongate nuclei perpendicular to the basement membrane
All the following criteria must be met : cytologic, architectural, size and must lack tumor cell (comedo) necrosis
- Exactly the same criteria as intermediate grade DCIS except for the lack of necrosis
- Lesions that fulfill some but not all criteria are designated atypical ductal hyperplasia
Uniform nuclei 2-3x size of a RBC (10-15 microns)
- Nuclei round to oval, regular, evenly dispersed chromatin
  - At most, mildly irregular, minimally pleomorphic
- Nuclei stand apart, do not overlap
- Nucleoli if present are inconspicuous
- Mitotic figures sparse to absent
  - Abnormal forms rare
Usual architectural types (may be pure or mixed)
- Cribriform
  - Dilated ducts filled with monotonous cells
  - Cleanly punched out spaces with resultant "Roman arches"
- Micropapillary
  - Dilated ducts lined by monotonous cells
  - Small finger-like or club-shaped protuberances with bulbous ends extending into the lumen
- Solid
  - Dilated ducts filled by sheets of monotonous cells
  - Cells may be arranged around small acini
Variant architectural types
Involved focus must be over 2 mm
- Must involve at least two ducts
- If under 2mm, designate as atypical ductal hyperplasia