Pathological Classification and Grading of DCIS
DCIS should be classified and reported based on nuclear grade (low, intermediate, or high), presence or absence of necrosis, and architectural pattern, as these features directly influence treatment decisions and risk of local recurrence. 1
Nuclear Grade Classification System
The most clinically relevant classification system for DCIS is based on nuclear grade rather than traditional architectural patterns, as nuclear grade correlates with recurrence risk and treatment outcomes. 1
Three-Tier Nuclear Grading:
- Low grade (good): Small, uniform nuclei with minimal pleomorphism and rare mitoses 1
- Intermediate grade: Moderate nuclear pleomorphism with intermediate features between low and high grade 1
- High grade (poor): Large, pleomorphic nuclei with prominent nucleoli and frequent mitoses 1
High nuclear grade and presence of necrosis (particularly extensive comedonecrosis) are associated with significantly higher risk of early local recurrence following breast conservation therapy. 1
Architectural Patterns
While less predictive of recurrence than nuclear grade, architectural patterns should still be reported as they have clinical relevance: 1
- Comedo: Characterized by central necrosis
- Cribriform: Sieve-like pattern with punched-out spaces
- Micropapillary: Small papillary projections without fibrovascular cores (tends to be more extensive and prone to multiple quadrant involvement) 1
- Papillary: True papillae with fibrovascular cores
- Solid: Solid sheets of cells filling ducts
The micropapillary pattern deserves special attention as it tends to be more extensive and prone to involvement of multiple quadrants, independent of nuclear grade. 1
Essential Pathology Report Elements
The pathology report must include these specific features to guide treatment: 1
- Nuclear grade (low, intermediate, or high) - mandatory
- Presence or absence of necrosis - mandatory
- Architectural pattern(s) present
- Estimated extent (size) of DCIS - critical for treatment planning
- Surgical margin status - whether DCIS is transected at margins and distance from nearest margin if negative
- Cell polarization (if applicable) 1
Clinical Implications for Treatment
Nuclear grade and necrosis are the primary pathologic features that determine treatment intensity: 1
- High-grade DCIS with necrosis: Higher risk of local recurrence; typically requires wider excision margins and radiation therapy is strongly recommended
- Low-grade DCIS without necrosis: Lower recurrence risk; may be candidates for less aggressive treatment approaches
- Intermediate-grade DCIS: Requires individualized assessment based on size, margins, and patient factors
Tumors with favorable sizes and grades are associated with increased rates of breast preservation and lower rates of radiotherapy use. 1
Important Caveats
- No single classification system has been universally adopted, so pathologists must clearly state which grading system is used 1
- Greatest consistency among pathologists is achieved using nuclear grade-based classification systems rather than architectural pattern-based systems 1
- No classification system can predict whether local recurrence will be in situ or invasive carcinoma 1
- Surgical margin assessment is arguably the most important pathologic feature for patients being considered for breast conservation 1
- Estrogen/progesterone receptors, DNA ploidy, S-phase, and oncogene amplification are not necessary for routine evaluation of DCIS 1