Benign Breast Lesions & BRCA Mutations

• The quiz consists of 17 questions, totaling 65 points, with a focus on essay-style questions and some multiple-choice.
• Review pathology questions, lectures, labs, and reading assignments.

Benign Breast Lesions & Fibrocystic Changes

• The three most common benign breast lesions are fibroadenomas, breast cysts, and fibrocystic changes, especially in pregnancies.
• The three primary components of fibrocystic changes are cysts, epithelial proliferation, and fibrosis.
• Cysts in fibrocystic changes result in fluid, epithelial proliferation results in many cells, and fibrosis results in few cells in Fine Needle Aspirations (FNAs).

BRCA1 and BRCA2 Mutations

• A BRCA1 mutation is associated with a slightly higher lifetime risk of developing breast cancer compared to a BRCA2 mutation.
• BRCA1 mutations are also associated with ovary, prostate, colon, and pancreas tumors.
• Individuals with BRCA1 mutations usually are younger, around 40-50 years old.
• BRCA1 mutations have a higher association with poorly differentiated, ER-, PR-, and Her2neu- tumors, known as Triple Negative.
• BRCA2 mutations are associated with a 37%-84% risk of developing breast cancer.
• Male breast cancer risk is markedly increased for individuals with BRCA2 mutations.
• BRCA2 mutations are associated with increased risk of ovary, prostate, pancreas, melanoma, bone, buccal cavity and pharynx, esophagus, gallbladder and bile duct, laryngeal, ocular, and stomach cancers.

Breast Metastasis

• Metastasis to lymph nodes indicates a poorer prognosis.
• Breast cancer often metastasizes to the brain, bones, lungs, and liver.

Breast Cytology Reporting Categories

• The categories for reporting breast cytology results are: insufficient, benign, atypical, suspicious, and malignant.

Cells in Benign Breast Samples

• Ductal Cells (Luminal Epithelial Cells): Line the lumen within breast ducts.
• Morphology: cohesive clusters, 2D sheets, smooth membranes, fine/even chromatin, delicate cytoplasm, honeycomb orientation, nucleus 1.5-2x of a RBC, distinct cell borders.
• Apocrine Cells: Normal ductal epithelium that undergo transformation, indicating some benign conditions/hormonal influences.
• Morphology: cohesive/flat sheets, eccentric nuclei, smooth membranes, finely granular/even chromatin, single nucleoli, abundant/granular/dense cytoplasm, distinct cell borders.
• Myoepithelial Cells: Hallmark of benign breast; surround ductal cells in breast ducts.
• Presence indicates benign reactions/inflammation/masses; absence usually indicates cancer.
• Morphology: stripped/scant cytoplasm, bipolar nuclei, dark/bland chromatin, appearance as naked nuclei, appear plump (football-shaped), often found ½ plane of focus above ductal cells.
• Foam Cells: Cells of unknown origin; associated with benign breast lesions and cysts, but can also be observed in cancer.
• Morphology: single cells/loose clusters, abundant multivacuolated cytoplasm, distinct cell borders, bland/reactive nuclei, round/oval-shaped.

Breast Cancer Subtypes - Hallmarks & Ancillary Testing

• Subareolar Abscess: Blockage of glands, showing squamous material and reactive atypia.
• Lobular Carcinoma: Lack of E-cadherin, resulting in loose cells.
• Low Grade Ductal Carcinoma In Situ (CIS): Characterized by microcalcifications.
• Phyllodes: Leaf-like projections.
• Ancillary studies for breast cancer include biomarker testing in carcinoma cases, flow cytometry in lymphoma cases, and molecular studies.

Diagnostic Rules for Breast Cancer Cytology

• Diagnose malignancy only when BOTH criteria are filled
• Cellularity of the smear (lots of cells to look at)
• Degree of cytologic atypia (cells look malignant)
• Do NOT diagnose malignancy definitively if there is
• Poor cellularity
• Absence of single, intact tumor cells (along with groups)
• Presence of naked, bipolar nuclei (myoepithelial cells, not present in cancer but present in benign reactions/masses)
• If other criteria are there but there are myoepithelial cells then the call would likely be suspicious

Ductal Cell Carcinoma (Invasive Ductal Carcinoma - IDC)

• Ductal carcinoma moves past the basement membrane into surrounding tissue.
• IDC commonly occurs in one breast and is the most common malignant tumor of the breast.
• Clinical presentation includes a palpable breast lump, change in breast size/shape, skin alterations (dimpling, orange peel-like skin, redness, scaliness, thickening, nipple discharge, nipple retraction/inversion), or it can be asymptomatic.
• Cytology shows pleomorphic tumor cells, infiltration of tumor cells into surrounding stroma, abnormal mitosis, high cellularity, irregular/poorly cohesive groups, and single cells.

ER/PR Testing

• ER- (estrogen receptor), PR- (progesterone receptor), and Her2neu- results, when all three are negative, make up the Triple Negative.
• Carcinomas that are negative for all three tests indicates high-grade malignancies which are hard to treat
• Triple negative carcinomas are harder to treat as hormone blockers can’t be used to slow them down
• Patients with the BRCA1 mutation have a higher risk of developing breast cancers that are associated with poorly differentiated ER-/PR-HER2- (triple negative)

General Aspects of Breast Cytology Reporting Categories

• Insufficient/Inadequate: Smear is not interpretable or is nondiagnostic.
• Common causes: low cellularity, obscured morphology due to blood, crushing artifact, poor fixation and degenerated cells.
• MD Anderson Cancer Center Group proposed that 4 - 6 well visualized cell groups with 10 or more cells / flat sheets as an adequacy criteria
• Samples that lack epithelial cells are considered inadequate in general, except.
• If the lesion is suspected to be lipoma or fat necrosis, the absence of epithelial clusters doesn't indicate inadequacy
• Benign: Benign epithelial clusters are seen with no atypia or malignant features.
• Cellularity is usually not high; cells are seen in flat sheets, depicting fine chromatin, smooth nuclear membrane, low nuclear cytoplasmic (N/C) ratio, no pleomorphism
• Fatty fragments are commonly seen
• Bare nuclei of myoepithelial cells are easily seen
• Histiocytes and apocrine cells can be found
• In duct ectasia: thickened material within macrophages and multinucleated giant cells
• Atypia (Favor Benign): Similar to the findings of benign but with higher cellularity, slight crowdedness, 3 dimensional groups, nuclear enlargement and pleomorphism
• Common lesions encountered in this category include proliferative fibrocystic change with or without atypia, papillary lesions, and lobular lesions including atypical lobular hyperplasia / lobular carcinoma in situ and some special types of breast carcinoma commonly missed in FNA, like lobular, tubular and cribriform
• Suspicious: Highly atypical findings but insufficient to be called malignant.
• Reasons: hypocellular or poorly preserved smear, findings are focally seen in a benign background, or the degree of atypia is more than described in atypical category but not sufficient for malignant category
• Common lesions encountered include atypical duct hyperplasia, low grade ductal carcinoma in situ, invasive carcinoma that wasn't adequately sampled, and special types of carcinoma like lobular, tubular and cribriform
• Malignant: Cellularity is usually high and the cytologic features are malignant (high N/C ratio, irregular nuclear contour, hyperchromasia, prominent nucleoli).
• Malignant cells are seen singly or in loose clusters.
• Necrotic debris might be seen in the background.
• Some special types of carcinoma can be specifically recognized or suspected, like mucinous, medullary-like, papillary

Invasive Lobular Carcinoma

• Ranges from 5% to 15% of invasive breast cancers and is most common in women around 45-50 years old.
• Presents with a higher false-negative rate due to its less defined appearance on mammography.
• Has a tendency to present multicentrically and thought to be to more commonly bilaterally.
• FNA is often poorly cellular with low to moderate cellularity.
• Individual cells, small chains, strands and groups- cells are discohesive (rather than sheets)
• Cytologic features include a single file pattern, eccentric nuclei in single cells, small nucleoli, well-defined cytoplasm, pale and scanty, intracytoplasmic lumens, uniform plasmacytoid cells with mild atypia, and occasional signet-ring or linear arrangement.

Mastitis and Duct Ectasia

• In duct ectasia, a milk duct in the breast widens, walls thicken, and the duct becomes blocked leading to fluid build up and can rupture.
• Duct ectasia primarily affects perimenopausal and multiparous women and the large ducts beneath the areola.
• Symptoms include thickened, bloody, or pussy nipple discharge.
• 25% of patients have a palpable mass
• Local pain is common
• Nipple may invert.
• Duct ectasia does not increase risk for breast cancer

Fat Necrosis

• Fat necrosis is composed of fragments of degenerated lipid, histiocytes, hemosiderin, and inflammatory cells.
• Multinucleated giant cells contain lipid deposits, with abundant foamy macrophages.
• Fat necrosis is often associated with trauma- breast surgery, with specimen containing degenerated lipid, histiocytes, hemosiderin, and inflammatory cells

Medullary Carcinoma

• Medullary is a subtype of Invasive Ductal Carcinoma (IDC).
• The tumor is a soft, fleshy mass that resembles a part of the brain called the medulla, making it a fibroadenoma-like mass.
• Medullary carcinomas are more common in women who have a BRCA1 mutation.
• Often “Triple Negative”.
• High-grade appearance (cells) but low grade behavior, growing slowly and not typically spreading past local lymph nodes.
• Grows in a diffuse pattern with no gland formation (syncytial, sheet-like growth)
• Requires more aggressive removal.
• Exhibits Lymphocytic infiltrate (cancer & lots of lymphocytes)
• Cytology shows poorly differentiated cells arranged in large sheets with a "syncytial" appearance, loose clusters & isolated cells, bizarre cells, large, pleomorphic nuclei, prominent & irregular macronucleoli, abundant cytoplasm, lymphoplasmacytic infiltrate, and mitotic figures +/- atypical.

Location & Mucinous Carcinoma

• The most common location of breast cancer is the upper outer quadrant.
• Mucinous Carcinoma (Colloid Carcinoma) is low grade, slow growing, and has a favorable prognosis.
• Mucinous Carcinoma presents as a large tumor, well-circumscribed, soft and jelly-like.
• On FNA, islands of tumor cells are seen in a sea of mucin and it is typically ER/PR & HER2 negative.

Nipple Discharge

• A spontaneous nipple discharge not related to lactation or pregnancy is an abnormal finding.
• Nipple discharge may result from a breast lesion such as papilloma or carcinoma, or hormonal abnormalities.
• Cytologic examination helps in identifying small breast lesions & papillomatosis when the patient has no palpable or mammographic abnormality.
• Bloody discharge is more likely to be malignant.
• Nipple discharge specimens are prepared by gently massaging the breast in the direction of the nipple, touching a glass slide to the secreted drops
• The discharge need not be smeared unless it is abundant, with slide fixed by spray fixation or by immersion in 95% ethyl alcohol, then stained with the Papanicolaou stain.

Benign vs Malignant Nipple Discharge

• Benign nipple discharge is usually sparsely cellular, containing ductal cells, foam cells (histiocytes), inflammatory cells, and red blood cells.
• Numerous groups of benign ductal cells, especially large, branching clusters, indicates intraductal papilloma or intraductal hyperplasia.
• Malignant nipple discharge displays enlarged ductal cells, isolated and in clusters, with variable nuclear size and shape, stripped nuclei, nucleoli, acute inflammation, blood, and necrotic debris.

Paget’s Disease

• Paget's cells are large with a large nucleus and pale, vacuolated cytoplasm, irregular nuclear borders, and prominent nucleoli.
• Cells may appear singly or in small clusters within the sample, often accompanied by inflammatory cells and cellular debris

Phyllodes Tumors

• Phyllodes are rare breast tumors that grow in the connective tissue of the breast and are typically smooth, firm lumps that can grow quickly.
• Stromal and epithelial proliferation predominates, typically affecting women in their 40s to 50s.
• Phyllodes Tumors present large, irregular lobulation, rapidly growing with features like fibroadenoma.
• Distinguished by features of the stroma, like increased cellularity, mitoses, and atypia
• Histologic finding: Leaf-like (phyllode) invaginations of large, branching ducts
• Suggest Malignant Phyllodes Tumor if there is a large tumor size (>10cm), Stromal overgrowth, increased mitotic activity and cytologic atypia
• FNA produces a dual population of epithelial cells and stromal cells.
• High stromal cellularity-KEY: large highly cellular stromal fragments with the leaf-like projections
• There are higher grade/malignant phyllodes tumors where Nuclear atypia and cellularity increases with the grade of the tumor.

Role and Limitations of FNA in Breast Cancer Diagnosis (Triple Test)

• All breast lesions should be evaluated by a “triple test” approach, which combines clinical, radiological, and pathological parameters to arrive at a final diagnosis and guide patient management.
• Best practice for pathology is a combination of core biopsy and FNA.
• FNA can increase the accuracy rate, minimizing false negative core biopsies due to sampling issues, as the FNA produces more passes and/or for assessing nearby lymph nodes.
• Breast FNA cytology does not give a definite diagnosis for the lesion, but enhances the sensitivity of cancer detection if combined with core needle biopsy
• Breast FNA cannot differentiate atypical ductal hyperplasia from low grade cancer
• Breast FNA cannot differentiate high grade in situ carcinoma from invasive cancer
• Breast FNA, as part of the triple approach, is a safe, reliable, accurate, fast, cost saving, almost complication free method that can reduce the number of more invasive procedures.

Triple Test Parameters

• All breast lesions should be evaluated by a “triple test” approach, which combines clinical, radiological, and pathological parameters to arrive at a final diagnosis and guide patient management.
• Clinical: presents with breast mass, symptoms of skin changes, size and shape of breast, discharge or pain
• Radiological: imaging, diameter and size and borders of mass, solid vs soft, where in the breast, bilateral vs unilateral
• Pathology: cytology, cell block, cytospin, er/pr/her2neu testing, core biopsy

Subareolar Abscess

• Subareolar abscess is an abscess of the areolar gland caused by blockage of these small glands-leads to infection.
• Typically begins with the squamous lining producing large amounts of keratin, forming keratin & plugging the duct-leading to rupture of the duct.
• Can occur in men or women, and is often a mixed infection which is predominantly anaerobic bacteria.
• Common causes: diabetes, nipple piercings, immunodeficiency
• Abscess can be clinically confused with breast cancer.
• Microscopically, there is squamous material +/- reactive atypia *(Hallmark), anucleated squames, metaplastic cells, parakeratotic material, granulomas material, large to giant histiocytes in rx to the foreign squamous cells, mixed inflammatory response (neutrophils, lymphocytes, plasma cells, foamy macrophages, granulation), occasional cholesterol crystals or clefts

Cytologic Differentiation - Ductal vs. Lobular Carcinoma

• For Lobular Carcinoma: smears with predominantly dyshesive malignant cells.
• Tumor cells are plasmacytoid
• Eccentric nuclei with prominent nucleoli
• Abundant cytoplasm intracytoplasmic lumens
• Bilateral
• For Ductal Carcinoma: displays a high number malignant cells.
• Big clusters of single cells
• Pleomorphic
• Chromatin abnormalities
• Hyperchromatic
• High N/C ratio
• Prominent nucleoli
• Necrosis
• Granular cytoplasm
• Microcalcifications
• Can form in tube depending on subtype
• Increased mitotic activity and tend to be unilateral.

Ductal Cancer Growth

• Ductal cancer begins with a growth of cells in a breast duct.
• Overgrowth of cells may develop in the breast duct. This is called hyperplasia.
• Over time, the cells develop changes that make them look different from typical cells.
• These cells may continue to build up and become trapped in the breast duct, causing ductal carcinoma in situ.
• Eventually the cancer cells may break out of the duct and become invasive breast cancer, spreading to other parts of the body.

Fibrocystic Changes

• Fibrocystic changes show proliferation of ductal and myoepithelial cells with occasional apocrine cells.
• Fewer naked nuclei (myoepithelial cells)
• Moderate to high cellularity
• Mild pleomorphism
• Lack of significant nuclear overlap or crowding
• Fine chromatin, small nucleoli
• Cellular maturation where some may be pyknotic
• Indistinct cell borders
• Cells are relatively cohesive and orderly
• Few stromal fragments
• Diffuse mass that is more difficult to feel on palpation
• Background with possible purulent exudate

Fibroadenoma

• Fibroadenoma is derived from the terminal duct lobular unit.
• Proliferation of stromal and glandular epithelial components within terminal duct lobular unit causes a high cellularity, rounded freely mobile mass.
• Fibroadenoma is specified to help distinguish it from fibrocystic changes.
• Abundant spindle stromal cells and naked nuclei
• Numerous epithelial cells of ductal type in large cohesive sheets
• Myoepithelial cells with naked, oval nuclei
• Chondroid matrix
• Stromal fragments embedded with spindle cells
• Antler-like papillary fronds