Benign breast disease

Question 1

Simple fibroadenoma

Answer 1

A proliferation of stromal connective tissue and epithelium arising from the terminal duct lobular unit
Simple: low-cellularity stroma, regular cytology
Similar appearance to a benign Phyllodes tumour on core bx
Clinical: firm, rubbery, mobile, increase in size during pregnancy/oestrogen therapy
13% of all palpable breast masses (60% in women aged 20)
20% multiple/bilateral
Mx:
- USS with followup in 6 months
- or USS and core bx if >23y
- excise if symptomatic, large, distorted, concerns re Phyllodes

Question 2

Complex fibroadenoma

Answer 2

Mass or nodule on USS/mammo
Cytology: sclerosing adenosis, duct epithelial hyperplasia, epithelial calcification
Mx: can leave after core bx if no increased suspicion of malignancy
Excise if stromal mitoses or overgrowth, nuclear pleiomorphism, fragmentation, adipose tissue infiltration

Question 3

Radial scar

Answer 3

Also known as complex sclerosing lesion if >1cm
Mimics breast cancer on mammogram
Core bx will show benign proliferation
If atypia present, requires surgical excision (30% upgrade to cancer)
If no atypia, followup (2x increased risk of cancer in long term)

Question 4

Concordance

Answer 4

The pathology findings must plausibly explain the imaging findings, in a multidisciplinary setting

Question 5

Papillary lesions

Answer 5

A heterogenous group of lesions (benign solitary intraductal papilloma, atypical papilloma, papillary cancer)

Clinical: breast mass, nipple discharge, radiological changes, bloody nipple discharge
Histo: epithelium-lined, branching, fibrovascular stalk
If atypia, 25-35% risk of upgrade to cancer

Excise if: atypia, >1cm, discordance
Or observe with short-term followup to assess stability of lesion
Twofold increase in risk of cancer without atypia
Fourfold increase in risk of cancer with atypia

Question 6

Sclerosing adenitis

Answer 6

Benign proliferation of myoepithelial cells and lobular acini
Clinical: mass on mammogram, architectural distortion + calcs

Excise if discordance
Twofold increased risk of breast cancer long term

Question 7

Atypical hyperplasia

Answer 7

Epithelial proliferation with atypical changes in the TLDU
ADH: monomorphic epithelial proliferation that fills the lumens, with cribiform architecture and punched-out secondary lumens
Similar to DCIS but only involve <2 ducts <2mm
10-30% core bx will underdiagnose DCIS
Absolute risk of breast cancer 1-2%/year
Mx: surgical excision
Followup with annual mammogram from 40y

Question 8

LCIS: define, 3 types, management

Answer 8

Expanded acini in the TLDU - monomorphic, discohesive cells
Must have >50% acini affected for diagnosis of LCIS
3 types: classic, pleiomorphic, florid (increasing risk of malignant transformation)
Mx: imaging if classic type, concordance with imaging, no other high-risk lesions
Or excision if pleiomorphic
It is an independent risk factor for breast cancer
Long-term: extensive surveillance, medication, prophylactic bilateral mastectomy

Question 9

Gynaecomastia: define, epidemiology, aetiology, exam, treatment

Answer 9

A benign proliferation of breast tissue caused by the increase in the ratio of oestrogen to androgen
Affects males in trimodal distribution: neonates, puberty, 60-70yo
Causes:
- genetic/chromosomal: Kleinfelters syndrome
- physiological
- cancers: Sertoli cell, Leydig cell, germ cell, RCC (produces b-hCG)
- cirrhosis, ESRF
- endocrine: hyperthyroidism
- drugs of abuse: alcohol, cannabis, anabolic steroids
- prescription drugs: spironolactone, ketoconazole, haloperidol, goserelin
Exam: bilateral, tender, central, circular.
Concerning findings: rapid growth, unilateral, non-tender, not centrally under nipple
Management:
- discontinue drugs
- observe (often spont disappears after 6/12)
- tamoxifen (can use in puberty), testosterone replacement if hypogonadal

Surgery if >12mo, psychological impairment, doesn’t respond to the above, has become fibrotic

Question 10

What is the pathophysiology of periductal mastitis?

Answer 10

Smoking causes metaplastic change from cuboidal to squamous epithelium
Duct ectasia
Fills with keratin plug: nidus for infection and abscess
Rupture of duct and drainage of abscess via shortest path to periareolar skin

Question 11

What is the pathology of lactational mastitis?

Answer 11

Milk stasis within duct
Crack or sore on skin from breastfeeding
Nidus for infection