L3 – Breast Pathology

Question 1

What are the main histological components of the normal breast?

Answer 1

The breast consists of glandular tissue (including the ductal system and terminal duct lobular units) and supportive stroma.

Question 2

How are the terminal duct lobular units (TDLUs) significant?

Answer 2

TDLUs represent the secretory portion of the breast and are the sites where many pathological changes begin.

Question 3

What are the two cell types that line the ductal–lobular system?

Answer 3

The inner epithelial cells and the outer myoepithelial cells, each identifiable by distinct immunohistochemical markers.

Question 4

Why is the structure of the ductal–lobular system clinically important?

Answer 4

It underpins the pathogenesis and diagnosis of both benign and malignant breast conditions.

Question 5

What are common benign breast conditions?

Answer 5

Conditions such as fibrocystic change, fibroadenoma, papilloma, and fat necrosis.

Question 6

How can fat necrosis mimic breast cancer radiologically?

Answer 6

Fat necrosis may display irregular borders and calcifications on mammograms, resembling malignancy.

Question 7

What is the typical age range for fibroadenomas?

Answer 7

They commonly occur in women aged 20–35 years.

Question 8

What is the significance of radial scars in breast pathology?

Answer 8

Although benign, radial scars can mimic carcinoma on imaging and are often categorised as B3 lesions requiring adequate sampling.

Question 9

How are breast carcinomas classified based on invasion?

Answer 9

They are classified as carcinoma in situ (non-invasive) or invasive carcinoma.

Question 10

What distinguishes ductal carcinoma in situ (DCIS) from invasive carcinoma? Delete

Answer 10

DCIS is confined within the ductal system with an intact myoepithelial layer, while invasive carcinoma breaches the basement membrane.

Question 11

Why is the distinction between in situ and invasive carcinoma important for treatment? Delete

Answer 11

In situ carcinomas generally have an excellent prognosis and may not require lymph node excision, whereas invasive carcinomas require more aggressive management.

Question 12

What role does hormone receptor status play in breast cancer management? Delete

Answer 12

Hormone receptor (ER/PR) positivity influences treatment decisions, including the use of anti-oestrogen therapies.

Question 13

How does the breast cancer screening programme impact prognosis?

Answer 13

Early detection via mammography screening significantly improves survival, as early-stage cancers have much higher 5‑year survival rates.

Question 14

How do myoepithelial cells aid in differentiating invasive from in situ breast lesions?delete

Answer 14

Their presence in ducts typically indicates a benign or in situ process, while their absence suggests invasion.

Question 15

What immunohistochemical markers are most useful for detecting myoepithelial cells? Delete

Answer 15

Markers such as p63, SMM, and CK5/6 are routinely used to highlight the myoepithelial layer.

Question 16

How can radiological imaging complement histological assessment in breast pathology? Delete

Answer 16

Imaging can detect microcalcifications, architectural distortions, and density changes that correlate with histopathological findings.

Question 17

How do proliferative benign conditions like atypical ductal hyperplasia influence breast cancer risk?

Answer 17

They increase the risk of developing subsequent carcinoma and require careful clinical surveillance.

Question 18

What genetic alterations are commonly observed in breast carcinoma?

Answer 18

Mutations in BRCA1/2, alterations in HER2, and changes in genes regulating cell cycle and apoptosis are frequent.

Question 19

What is the prevalence of breast carcinoma in women?

Answer 19

Breast carcinoma accounts for 20% of all cancers in women, with a 1 in 8 lifetime risk in the UK.

Question 20

How are breast carcinomas classified based on invasion?

Answer 20

They are classified as carcinoma in situ (non-invasive) or invasive carcinoma.

Question 21

What distinguishes ductal carcinoma in situ (DCIS) from invasive carcinoma?

Answer 21

DCIS is confined within the ductal system with an intact myoepithelial layer, while invasive carcinoma breaches the basement membrane.

Question 22

Why is the distinction between in situ and invasive carcinoma important for treatment?

Answer 22

In situ carcinomas generally have an excellent prognosis and may not require lymph node excision, whereas invasive carcinomas require more aggressive management.

Question 23

List key risk factors for breast carcinoma.

Answer 23

Female sex, age, reproductive history (early menarche, late menopause, nulliparity), obesity, family history, and atypical hyperplasia.

Question 24

What role does hormone receptor status play in breast cancer management?

Answer 24

Hormone receptor (ER/PR) positivity influences treatment decisions, including the use of anti-oestrogen therapies.

Question 25

What are common treatment modalities for breast cancer?

Answer 25

Surgery (breast-conserving procedures or mastectomy), chemotherapy, radiotherapy, hormonal therapy, and immunotherapy.

Question 26

How do myoepithelial cells aid in differentiating invasive from in situ breast lesions?

Answer 26

Their presence in ducts typically indicates a benign or in situ process, while their absence suggests invasion.

Question 27

What immunohistochemical markers are most useful for detecting myoepithelial cells?

Answer 27

Markers such as p63, SMM, and CK5/6 are routinely used to highlight the myoepithelial layer.

Question 28

How can radiological imaging complement histological assessment in breast pathology?

Answer 28

Imaging can detect microcalcifications, architectural distortions, and density changes that correlate with histopathological findings.

Question 29

How do proliferative benign conditions like atypical ductal hyperplasia influence breast cancer risk? Check

Answer 29

They increase the risk of developing subsequent carcinoma and require careful clinical surveillance.

Question 30

How does breast density affect cancer risk and detection?

Answer 30

High breast density not only increases the risk of cancer but also can obscure lesions on mammographic imaging.

Question 31

What is the role of sentinel lymph node biopsy in breast cancer management?

Answer 31

It provides crucial staging information with minimal morbidity compared to complete axillary dissection.

Question 32

How do hormone receptor statuses guide therapeutic decisions in breast cancer?

Answer 32

They determine the use of anti-oestrogen agents, which can significantly impact patient outcomes.

Question 33

What tissue layers separate the breast from the pectoralis muscle?

Answer 33

The deep fascia separates the breast from the pectoralis muscle.

Question 34

What is the function of Cooper’s ligaments?

Answer 34

They anchor the breast to the skin, helping to maintain its position.

Question 35

How does breast anatomy explain nipple retraction in malignancy?

Answer 35

Fibrosis and traction on Cooper’s ligaments by a tumour cause nipple retraction.

Question 36

Why are terminal duct lobular units (TDLUs) crucial in breast pathology?

Answer 36

Most benign and malignant breast diseases originate in the TDLUs.

Question 37

What is the role of myoepithelial cells in distinguishing benign from malignant breast lesions?

Answer 37

Myoepithelial cells are destroyed in invasive carcinoma but preserved in benign and in situ lesions.

Question 38

Why can invasive carcinomas still appear to have a basement membrane?

Answer 38

Invasive carcinomas can synthesise their own basement membrane material after breaching the original one.

Question 39

What is the significance of chronic lymphocytic lobulitis in breast diagnosis?

Answer 39

It presents as a hard breast mass mimicking malignancy, especially in diabetic women over 40.

Question 40

What condition is characterised by ductal dilation and plasma cell infiltration?

Answer 40

Mammary duct ectasia.

Question 41

What clinical symptom is often associated with mammary duct ectasia?

Answer 41

Bloody nipple discharge.

Question 42

Why can fat necrosis lead to confusion with breast cancer on imaging?

Answer 42

Fat necrosis results in dystrophic calcification, mimicking suspicious imaging features.

Question 43

What is the key microscopic feature of a radial scar?

Answer 43

A fibroelastic core with radiating ducts and lobules.

Question 44

Why are radial scars categorised as B3 lesions?

Answer 44

Because a small sample cannot exclude associated carcinoma elsewhere. Associated with Tubular carcinoma.

Question 45

What defines a fibroadenoma histologically?

Answer 45

It is a well-circumscribed, biphasic tumour composed of epithelial and fibrous stromal elements.

Question 46

Why might fibroadenomas grow rapidly during pregnancy?

Answer 46

Oestrogen stimulation during pregnancy promotes their rapid growth.

Question 47

What clinical context differentiates a benign nipple discharge from a pathological one?

Answer 47

Milky discharge during pregnancy is physiological, whereas bloody discharge raises suspicion.

Question 48

Why does Paget’s disease of the nipple often signal underlying DCIS?

Answer 48

Malignant epithelial cells infiltrate the nipple epidermis in Paget’s disease.

Question 49

How do lobular carcinomas differ from ductal carcinomas clinically and histologically?

Answer 49

Lobular carcinomas tend to be multifocal, bilateral, subtle clinically, and form single-cell rows histologically.

Question 50

Why might invasive lobular carcinoma be missed on mammography?

Answer 50

They produce minimal desmoplasia, making them difficult to detect on mammograms.

Question 51

What staining marker is often lost in invasive lobular carcinoma?

Answer 51

Loss of E-cadherin expression.

Question 52

What is the classic microscopic growth pattern of invasive lobular carcinoma?

Answer 52

Single-file infiltration of tumour cells.

Question 53

What is the main histological difference between DCIS and invasive ductal carcinoma?

Answer 53

Presence of a myoepithelial layer in DCIS but not in invasive ductal carcinoma.

Question 54

Why are multifocal lobular carcinomas managed differently from ductal carcinomas?

Answer 54

MRI is preferred before surgery to detect multifocal disease.

Question 55

How does tumour necrosis lead to microcalcifications in DCIS?

Answer 55

Necrotic tumour debris calcifies within ducts, producing microcalcifications.

Question 56

Why is early detection critical for breast cancer prognosis?

Answer 56

Survival is significantly higher with early-stage detection compared to late-stage disease.

Question 57

What is the primary radiological target in breast cancer screening?

Answer 57

Microcalcifications, especially linear or branching ones suggestive of DCIS.

Question 58

At what age and frequency is routine mammographic screening recommended in the UK?

Answer 58

Every 3 years for women aged 48–69.

Question 59

Why is breast screening not typically started before age 48?

Answer 59

Dense breast tissue in younger women can obscure abnormalities on mammograms.

Question 60

What histological feature underlies the mammographic appearance of microcalcifications in DCIS?

Answer 60

Central necrosis within ducts leading to dystrophic calcification.

Question 61

What role do histopathologists play beyond diagnosing breast cancer?

Answer 61

They determine tumour type, grade, receptor status, excision margins, and guide treatment.

Question 62

What does a B5a designation indicate on breast core biopsy?

Answer 62

B5a indicates carcinoma in situ (non-invasive cancer).

Question 63

Why is immunohistochemistry critical for breast cancer receptor testing?

Answer 63

To assess hormone receptor and HER2 status to guide targeted therapies.

Question 64

What is the significance of HER2 positivity in breast cancer treatment?

Answer 64

HER2 positivity predicts benefit from trastuzumab (Herceptin) therapy.

Question 65

What drug targets HER2-positive breast cancers?

Answer 65

Trastuzumab (Herceptin).

Question 66

What is the function of Oncotype DX testing in breast cancer management?

Answer 66

It predicts the need for chemotherapy in hormone receptor-positive, HER2-negative early breast cancers.

Question 67

How does hormone receptor positivity influence adjuvant breast cancer treatment?

Answer 67

ER/PR positivity indicates benefit from anti-oestrogen therapies like tamoxifen.

Question 68

Why is radiotherapy used after breast-conserving surgery?

Answer 68

To reduce local recurrence after breast-conserving surgery.

Question 69

What pathological features predict poor prognosis in breast cancer?

Answer 69

Tumour size, grade, lymph node involvement, lymphovascular invasion, receptor status.

Question 70

What is peau d’orange and what causes it in breast cancer?

Answer 70

Obstruction of dermal lymphatics by tumour cells causes skin oedema and dimpling (peau d’orange).

Question 71

What differentiates a benign cyst rupture from an invasive cancer in breast imaging?

Answer 71

Benign cyst rupture can mimic cancer radiologically but lacks invasive features histologically.

Question 72

What typical histological feature distinguishes lobular carcinoma in situ (LCIS) from ductal carcinoma in situ (DCIS)?

Answer 72

LCIS preserves lobular structure with uniform filling of acini, while DCIS expands and distorts ducts.

Question 73

Why are invasive lobular carcinomas more likely to metastasize to unusual sites?

Answer 73

Invasive lobular carcinomas have a propensity for metastasis to sites like the peritoneum, meninges, and gastrointestinal tract.

Question 74

What common clinical presentation leads to a breast biopsy?

Answer 74

A palpable lump.

Question 75

How does age affect the likelihood of benign versus malignant breast lumps?

Answer 75

Benign lumps are more common in younger women; malignancy rates increase with age.

Question 76

What factor increases breast cancer risk in nulliparous women?

Answer 76

Pregnancy delays or absence (nulliparity) increase oestrogen exposure over time.

Question 77

How does obesity contribute to breast cancer risk?

Answer 77

Adipose tissue produces oestrogen, promoting breast carcinogenesis.

Question 78

Why are sentinel lymph node biopsies performed in breast cancer surgery?

Answer 78

To stage axillary lymph nodes while minimising surgical morbidity.

Question 79

What are the key prognostic factors considered after breast cancer surgery?

Answer 79

Tumour size, histological grade, lymph node status, hormone receptor status, HER2 status, and vascular invasion.