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Reading File
Here is a thorough explanation of everything on this textbook page, with details expanded from authoritative sources.
What This Page Covers
The page is from a pathology textbook (Harsh Mohan / similar Indian pathology text) and covers two major topics in breast pathology:
1. Lobular Carcinoma In Situ (LCIS)
Key Points from the Page
Gross: No visible tumour - LCIS is not palpable or grossly visible.
Histology (the underlined text):
- LCIS is characterized by filling up of terminal ducts, ductules, or acini by rather uniform cells
- Cells are loosely cohesive (this is the hallmark - unlike DCIS cells which are cohesive)
- Cells have small, rounded nuclei with indistinct cytoplasmic margins
- Lesions are typically multicentric and involve bilateral breasts
Why This Matters Clinically
LCIS is NOT treated as a true malignancy - it is a risk marker, not a direct precursor:
- ~25% risk of developing invasive cancer in the ipsilateral breast over 10 years
- ~30% risk in the contralateral breast (this is the distinctive feature - risk is bilateral and roughly equal on both sides)
- Managed with surveillance (not mastectomy in most cases), often with chemoprevention (tamoxifen/aromatase inhibitor)
The loose cohesion of cells in LCIS occurs because of loss of E-cadherin (a cell adhesion molecule) - this is the molecular hallmark that distinguishes lobular lesions from ductal ones, and it also explains why lobular carcinoma tends to infiltrate in a single-file pattern when it becomes invasive.
2. Invasive (Infiltrating) Breast Carcinoma - NST
Terminology Clarification (why the new name?)
| Old Name | New Name | Reason for Change |
|---|---|---|
| Infiltrating Duct Carcinoma-NOS | Invasive Carcinoma of No Special Type (NST) | The term "duct" was misleading - the tumour actually arises from the Terminal Duct Lobular Unit (TDLU), not the ducts themselves |
This is an important conceptual point: both DCIS and invasive NST carcinoma originate in the TDLU - the functional unit where most breast carcinomas begin.
Key Facts about Invasive Carcinoma NST
- Most common type of breast carcinoma - accounts for ~75-80% of all invasive breast cancers
- It's a "diagnosis of exclusion" - tumours that don't fit into any specific histologic subtype (lobular, mucinous, tubular, papillary, etc.) fall here
- Gross: Usually presents as a hard, irregular, gritty mass with a desmoplastic (fibrotic) stromal reaction; produces a characteristic grating sound when cut
Histologic Grading (Nottingham Score)
All invasive carcinomas are graded using 3 parameters scored 1-3:
| Parameter | Grade 1 | Grade 2 | Grade 3 |
|---|---|---|---|
| Tubule formation | >75% | 10-75% | <10% |
| Nuclear pleomorphism | Small, uniform | Moderate | Marked, pleomorphic |
| Mitotic rate | Low | Intermediate | High |
Total score: 3-5 = Grade 1 (well diff.); 6-7 = Grade 2 (moderate); 8-9 = Grade 3 (poorly diff.)
3. The Three Histology Diagrams at the Bottom
These illustrate growth patterns seen within breast duct spaces (relevant to DCIS patterns):
| Pattern | Appearance | Key Feature |
|---|---|---|
| Papillary | Finger-like projections with fibrovascular cores extending into duct lumen | Branching fronds of epithelial cells |
| Cribriform | Sieve-like: cells fill the duct but leave neat, punched-out round spaces | "Swiss cheese" or "Roman bridge" pattern |
| Uniform cells (Solid) | Duct completely filled with a monotonous sheet of cells, no gland formation | Solid sheets, no architecture |
These patterns are used to classify DCIS (Ductal Carcinoma In Situ) subtypes. The cribriform pattern is associated with low-to-intermediate grade DCIS, while solid pattern with necrosis (comedonecrosis) = high grade/comedo DCIS.
Quick Comparison: DCIS vs LCIS
| Feature | DCIS | LCIS |
|---|---|---|
| Palpable mass | Can form a mass | No |
| E-cadherin | Positive | Negative (lost) |
| Cell cohesion | Cohesive | Loose (discohesive) |
| Bilaterality | Usually unilateral | Bilateral |
| Risk | Ipsilateral, same breast | Bilateral, ~equal |
| Precursor vs. Risk marker | True precursor | Risk indicator |
| Treatment | Excision ± radiation | Surveillance/chemoprevention |
Sources: Robbins, Cotran & Kumar - Pathologic Basis of Disease (Types of Invasive Breast Carcinoma, Histologic Grading); Mulholland & Greenfield's Surgery (Lobular Carcinoma In Situ section)
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