PathElective Breast Pathology Flashcards
Two types of lobular cell
On the left: Luminal epithelial cells (cuboidal cells on inner layer)
On the right: Myoepithelial cells (outer layer resting on the basement membrane)
Lactiferous breast tissue
There is hypertrophy of the lubular cells and increase in the number of lobules
Epithelial hyperplasia in the breast
Refers to the combination of ductal and lobular hyperplasia
If you zoom in to high power you may see two or three layers of ductal epithelial cells (just one is normal).
This is a form of fibrocystic disease, but is on the more concerning end due to the presence of hyperplasia (less concerning would be just cysts). This is associated with a higher risk of malignancy, but is not itself a pre-malignant lesion.
This is a fibroadenoma.
Note that it is mostly fibrous tissue, with small pockets of glandular tissue.
Classified as a benign mesenchymal tumor. Often calcifices over time (in older patient).
Invasive lobular carcinoma with it’s characteristic “Indian file” spreading
There is often little or no stromal reaction, making these lesions difficult to palpate / detect on exam.
Elston-Ellis grading system
Calcium oxalate on a slide
Does not take up hematoxylin, and thus you can only see these when the condenser is flipped down or with a polarizer
Sclerosing adenosis, a benign mimicker of carcinoma
Myoepithelial cells are reassurring against carcinoma, but are hard to see. Should have an overall loular (circumscribed and rounded) architecture. There also should be no desmoplastic reaction.
In order to confirm benignity, you may need to stain for myoepithelial cells.
Desmoplasia
Growth of fibrous tissue around disease, usually cancer.
In dermatopathology, desmoplasia itself can also be malignant.
Apocrine metaplasia
When the epithelial cells lining the ducts take on an apocrine appearance.
Characterized by lots of pink cytoplasm (oncocytic), a hobnail profile, and enlarged nuclei with prominent nucleoli. They have an almost brush-border like apical surface with a bright pink hue.
Hormonally responsive and androgen receptor positive. Suggestive of benignity.
Phyllodes tumor
A biphasic lesion of the breast, similar to a fibroadenoma. Phyllodes means “leaf-like.’
Graded based on how aggressive the stromal growth pattern is, ranging from benign to malignant.
On low-power it appears to have open spaces and curving sinuses, without any nested glandular tissue like you see in a fibroadenoma.
Fat necrosis
The key features: lipid droplets/disrupted fat cells, foamy macrophages, giant cells, edema and hemosiderin, acute inflammation, fibrosis and calcification (if the lesion is older)
Here you can see the ghosts of fat cells surrounded by macrophages that are locking-in the fat.
Intraductal papilloma
These can be hard to differentiate from papillary carcinomas, but the latter are rare. The key feature you are looking for is the presence of myoepithelial cells (arrowheads). These reassure you that this is a benign lesion.
Lobular and Ductal
Whether something is lobular or ductal is irrespesctive of where you find it. They refer to distinct morphologic patterns. There are also many ‘tweener’ lesions that are signed out as “mixed mammary carcinoma.”
Lobular vs Ductal hyperplasia
Ductal hyperplasia is super common and almost always benign.
Benign lobular hyperplasia is not a thing
Usual ductal hyperplasia
Cells have an overall pale look (“normochromic”). They appear jumbled overlapping, or streaming – almost syncytial.
“Clot of ductal cells” is a classic look for usual ductal hyperplasia. There should be slit-like openings on the sides of the duct lumen filled with mucus. Nuclei may vary slightly in size, but should have smooth borders and uniform chromatin. May look cribriform on low-power, but on high-power nuclei should appear streaming (flowing parallel to the lumen as opposed to radially).
Low-grade DCIS
Takes some getting used to, as it is actually more uniform than healthy breast tissue. It is recognized more by architecture than by cellular features.
Nuclei are hyperchromatic and cell margins are distinct.
High grade DCIS
Cells are pleomorphic with prominent nucleoli.
There may be central-ductal necrosis (asterisk), indicating comedo-type DCIS.
What atypical ductal hyperplasia looks like
Somewhere between usual hyperplasia and DCIS, but not with all the features of DCIS, OR a small focus of DCIS within usual ductal hyperplasia.
What to do when you see atypical ductal hyperplasia in a core biopsy
GET MORE TISSUE
Atypical ductal hyperplasia is highly likely to arise in association with a true DCIS
Tubular-variant ductal carcinoma
A very well-differentiated form of invasive ductal carcinoma. Well-formed tubules with pointed ends (arrow) and round, monotonous cells infiltrate through stroma and fat. The myoepithelial layer is absent and there is a substantial demoplastic reaction.
May coexist with lobular carcinoma.
Mucinous- or colloid-variant ductal carcinoma
Pools of mucin with floating fragments of neoplastic epithelium.
Medullary-variant ductal carcinoma
Well-circumscribed, yet ugly, groups of cells with a dense lymphocytic infiltrate
Micropapillary-variant ductal carcinoma
As the name implies
Poorer prognosis
Adenoid cystic carcinoma
A biphasic tumor of epithelial and myoepithelial cells
Identical to the salivary tumor of the same name
Metaplastic breast cancer
Tumor in which there is a squamous, mesenchymal, or spindle-cell component, such as cartilage, bone, of frank sarcoma.
Prognosis depends upon grade.
Lobular carcinoma-in-situ
Note the cell morphology.
Homogeneous with a round fried-egg shape and pale cytoplasm, discrete borders, and a round central nucleus. Cells retain this bland cytology even through to invasive carcinoma. Intracytoplasmic vacuoles and signet rings may also be seen.
Often multifocal and bilateral. Progression to cancer is not inevitable or predictable. As a result, unlike DCIS, excision is not the goal of treatment.
E-cadherin in breast pathology
The absence of E-cadherin is what gives lobular processes their characteristic discohesive morphology (fried egg with distinct borders surrounded by extracellular fluid).
Staining for E-cadherin can help differentiate a lobular from ductal process.
Lobular is negative, ductal is positive.
Atypical lobular hyperplasia
Generally translated as “I’m really worried about LCIS, but couldn’t quite get there”
Invasive lobular carcinoma
Has the classical “indian file” pattern. forming single-file lines or concentric circles.
Often little or no desmoplastic stroma reaction, making the lesion difficult to palpate or detect.
If you diagnose a breast carcinoma, you need to stain for. . .
. . . ER, PR, HER2
Papillary nomenclature for the breast
Papilloma: Benign lesion with papillary architecture. Myoepithelial cells and fibrovascular core are present. Within a papilloma, you mave have usual ductal hyperplasia, atypical ductal hyperplasia, or DCIS, all of which are diagnosed as “arising in a papilloma.”
Within the DCIS family, you may have a micropapillary (projections w/o fibrovascular core), papillary (projections w/ fibrovascular core), or solid papillary architecture.
Papillary carcinoma is a spceific type of carcinoma with a papillary architecture, homogeneous columnar cells, and circumscribed profile. It is a single discrete lesion. The fibrovascular core should have no myoepithelial cells. Not really considered a true, invasive carcinoma.
Ductal ectasia
Present focally in 30-40% of peri- and post-menupausal women, but usually asymptomatic. Can occur in younger women as well. Symptomatic ductal ectasia is 3x more likely in smokers.
Characterized by periductal inflammation with plasma cells and foamy macrophages, and often significant intra-ductal foamy macrophage infiltrate. Granulomas, xanthogranulomas, and acute inflammation may also be present. There is ductal dilation and may be periductal fibrosis.
May progress to duct destruction with “garland ring” figures
This is a “garland ring”, a former duct that has undergone luminal fibrosis and destruction in the setting of ductal ectasia.
“Brisk lymphocytic infiltrate”
Lymphoytes visualize within the tumor in large quantities
Should be noted as this predicts favorable response to neoadjuvant therapy.
Staining for myoepithelial cells
p63
Toker cells
Also called “clear cells of the nipple”
Cells normally found in the nipple epidermis. Main ddx for Paget’s of the nipple, which is why they are so important to pathologists.
Usually seen singularly, but can also be seen in collecting into small glands.
