Clonal proliferation of epithelial cells that is limited to the duct (intact basement membrane; maintains myoepithelial layer).
There is NO invasion into the surrounding tissues.
DCIS constitutes ~15-30% of all cancers in women receiving screening for breast cancer.
Bilateral in 10-20% of cases..
Excision is curative in more than 95% of cases. If untreated, risk for development of cancer is 1% per year.
8-10x increased risk of developing cancer
Has a loss of 16q and 17p
Ill-defined lump on palpation, but most often found incidentally on mammography (due to dystrophic calcifications in response to focal necrosis)
Microcalcifications associated with DCIS:
Irregular clusters, linear, or branching patterns of microcalcifications represent about 20% chance of malignancy and should be biopsied or resected.
Radiographs of resection specimens help pathologists to sample the areas of greatest concern more heavily.
If possible, the entire lesional area should be submitted.
Mention that histopathologic correlation with the specimen radiograph was performed in the pathologist’s comment section of the report.
Clinicians & radiologists want to correlate the abnormal clinical picture/imaging findings to pathology. If the requisition sheet says there should be calcifications present but you don’t see any, consider X-raying the block to make sure calcifications are present and get deeper levels. If you still can’t find any calcs, MENTION IT! They may have missed the lesion and need to go back!
Histologic patterns in DCIS:
Uniform, well demarcated secondary lumens (Formed by sharp radial distribution of tumor cells)
Referred to as “cookie cutter” or “punched out” lesions
Sharp, well demarcated margins
Micropapillary (& Papillary type) DCIS
Micropapillary DCIS has fingertip-like papillary projections into lumen (they do NOT have a fibrovascular core)
Typically have very narrow base with broadened, bulging tips that connect to each other forming “Roman bridges”.
Intervening epithelium is usually flat
Low grade nuclei (unusual cases with high grade nuclei, frequent mitosis and necrosis)
Cells fill and expand the duct lumina, but still confined by basement membrane
Uncommon, but generally good prognosis even if there is microinvasion (<1mm)
Basically, is just solid DCIS that has central necrosis +/- calcifications
Necrosis is what causes the “cheesy material” from the ducts with pressure (similar to comedone)
Prominent periductal fibrosis with minimal chronic inflammation
Other patterns of DCIS (not pictured):
NUCLEAR GRADING OF DCIS
Van Nuys System
Classification system for DCIS primarily based on the nuclear grade, presence of necrosis, size and margin status.
If a focus of DCIS is ER positive, attenuation of estrogen effect (by receptor blockade or by inhibition of aromatase enzyme involved in estrogen production) is used to reduce local recurrence.
“Clear margins” not clearly defined. However, a margin of 1 cm (10 mm) appears to be adequate for DCIS and likely obviates the need for radiation therapy in most cases.
LOW GRADE DCIS
Uniform, round, hyperchromatic nuclei that are relatively evenly spaced
Still surrounded/confined by basement membrane
Increased monomorphic cells entirely filling the duct in specific architectural pattern
Mild increase in nuclear to cytoplasmic ratio
Well-defined cell membranes
Minimal hyperchromatism; homogeneous chromatin distribution
No intermingled myoepithelial cells present within the cellular proliferation
Criteria to diagnose low grade DCIS:
More than one focus of these (low grade) atypical glands should be identified to call it DCIS or >2 mm in size. (If only a single focus, consider calling it ADH instead)
Both the characteristic low grade nuclear morphology and an architectural pattern are needed.
Requires some degree of geographical extent per pathologist’s interpretation. Commonly used opinions:
See >1 minute focus of low grade DCIS be present
Total extent of the process be 2 mm or more
3 or more ducts involved
HIGH GRADE DCIS
Compelling nuclear atypia
Often has central necrosis (but not reqd to make the diagnosis)
Still can form architectural patterns (comedo, solid, micropapillary etc) +/- microcalcifications
No quantitation requirements needed to make this diagnosis.
If you see nuclear atypia or central necrosis, CALL IT HIGH GRADE!
Make sure to look for signs of invasion!
Criteria to diagnose high grade DCIS:
The diagnosis of high grade DCIS can be done in a single duct of any size. If you see nuclear atypia, it automatically makes it high grade!
Neither the architecture of the intraductal proliferation nor the amount need to be considered in the diagnosis of high grade-intraductal carcinoma
DCIS vs. Invasive Carcinoma
If there is a questionable focus of invasive-appearaning cancer adjacent to DCIS, lean away from calling it invasive. It may just be a tangential section through the DCIS.
An intact basement membrane or myoepithelial cell layer favors non-invasive.
Remember that some invasive carcinomas still retain ME cells and that ME cell layer is discontinuous and may not stain in in all benign lesions.
If definite invasive component extends <1 mm into the stroma, the term “microinvasion” can be used.