Chapter 19 - Breast Flashcards
Why are FNAs rarely performed on breast?
Breast cancer is an architectural diagnosis, not a cytologic diagnosis.
What is the functional unit of breast?
How does it appear?
The terminal duct-lobular unit (TDLU).
Acini are arranged around ducts. All are lined with an outer myoepithelial layer in addition to the inner epithelial layer. There is also a basement membrane.
What are the three things that should be reported on any breast biopsy?
Tumor grade / differentiation
An explanation for microcalcifications
An explanation for mass
How do microcalcifications appear?
What can cause a mass, besides cancer?
Usually gritty & dark purple, but can take on the form of calcium oxalate (clear & refractile)
Fibrosis, cysts, fat necrosis, benign tumors…
Recall six forms of fibrocystic changes.
Fibrosis
Cysts
Usual duct hyperplasia
Adenosis / Sclerosing adenosis
Apocrine metaplasia
Fibroadenomas
Describe the appearance of adnosis & sclerosing adenosis.
Adenosis: Too many glands or lobules, looks crowded & worrisome.
Sclerosing adenosis: Lobules squeezed together by fibrosis, obscuring the myoepithelial layer.
Describe the appearance of apocrine metaplasia.
Epithelial cells look apocrine (bright pink, hobnailed, enlarged nuclei similar to Hurthle cells).
Describe the appearance of fibroadenoma.
Biphasic lesion with thin, branching ducts with a myxoid halo in a fluffy pink stroma compressing them into slits.
*can hyalinize & calcify*
What is phyllodes tumor, and how does it appear?
A biphasic lesion resembling a fibroadenoma but with a much more cellular stroma in a leaf-like pattern.
What are the morphologic traits of fat necrosis?
Disrupted & irregular fat cells
Foamy macrophages & giant cells
Edema & hemosiderin
Acute inflammation
Fibrosis & calcification (older lesions)
What can happen to an intraductal papilloma?
It can become fibrotic (sclerosing papilloma) or calcified with age.
Rarely, carcinoma can arise from it.
Describe the appearance of usual ductal hyperplasia.
Normochromic, pale & heterogeneous cells which appear jumbled & overlapping or even syncytial, streaming in the ducts.
How does DCIS appear?
What are its patterns?
Monotonous, clonal cells with evenly spaced cells. Becomes pleomorphic and pink when high-grade.
Cribriform, solid, comedo, micropapillary
What is atypical ductal hyperplasia?
An in-between diagnosis from usual ductal hyperplasia and DCIS. Usually for a focus <3mm, and generates additional tissue.
Describe the appearance of IDC and its most common form.
(scirrhous)
Large cellular & ugly lesion with dense desmoplasia with necrosis and mitoses. Nests can imitate ducts or tubules & become necrotic.
Name six variants of IDC.
Tubular
Cribriform
Mucinous / Colloid
Medullary
Adenoid cystic
Metaplastic
Describe the appearance of LCIS.
What is noteworthy about its distribution?
Homogenous, round fried-egg shape. Intracytoplasmic vacuoles are common.
It is often multifocal and bilateral.
How is LCIS often found?
What is atypical lobular hyperplasia?
Incidentally, it is not mass-forming.
Another vague diagnosis that falls short of LCIS.
What is E-cadherin, and what is its significance in breast?
It is a cell surface adhesion molecule, which is lost in lobular lesions resulting in single-file patterns.
Describe the appearance of ILC.
Bland, plasmacytoid cells in single files or rings without much desmoplasia. Sneaky–get a cytokeratin.
How is Elston grade determined?
Tubule formation (1-3)
Mitotic rate (1-3)
Pleomorphism (1-3)
What is solid papillary growth pattern?
Within DCIS, it is an architectural type with solid balls of cells with entombed residual fibrovascular cores.
What is papillary carcinoma?
A specific type of carcinoma, with papillary architecture, columnar cells, and a circumscribed profile. The Fibrovascular cores have no myoepithelial cells.
What entities may be lumped under “metaplastic carcinoma”?
Squamous carcinoma (actually ductal with squamous diff)
Low-grade spindle cell
High-grade with spindle cell features
Any carcinoma with an existing sarcoma (IE carcinosarcoma).
Normal breast
Left: Terminal duct lobular unit
Right: Benign gland with epithelial and myoepithelial cell layers
Left: Usual calcifications
Right: Calcium oxalate crystals with foamy macrophages response
Fibrocystic disease
Arrow: Apocrine metaplasia
Sclerosing adenosis
Tiny tubules trapped in a fibrotic stroma and among fat (arrow). Intact myoepithelial layer on IHC!
Fibrocystic disease
FIbroadenoma
Arrow: Ducts compressed into slits
Arrowhead: Secretory lobules in edematous stroma
Fat necrosis
Arrow: Foamy macrophages ringing dead adipocytes.
Arrowhead: Fibrosis between fat cells
Intraductal papilloma
Arrow: Distinct fibrovascular cores
Inset: Intact myoepithelial cells (arrowhead)
(florid) Usual ductal hyperplasia
Arrow: Peripheral ring of slit-like spaces
DCIS
Arrow: Cribriforming with polarization around tiny ducts
Arrowhead: High-grade pleomorphic cells with nucleoli and necrosis (asterisk)
IDC. Note pronounced desmoplasia.
Inset: Irregularly shaped tumor nests with edema and fibrosis.
Tubular carcinoma (IDC subtype)
Arrow: Well-formed tubules with pointed ends
Arrowhead: Desmoplasia and loss of myoepithelial cells
Mucinous carcinoma (IDC subtype).
Arrow: Clumps of cells in a pool of mucin dissecting into stroma.
LCIS
Arrow: Montonous cells with distinct cell borders and small round nuclei.
Arrowhead: Cytoplasmic vacuoles
ILC
Arrow: Single-file lines of cells. Note little to no desmoplasia.
