STEPTRACKERREPRODUCTIVE | PATHOLOGY + ENDOCRINE | HIGH-YIELD REVIEW

Benign Breast Disease

Lumps, pain, discharge and inflammation that aren't cancer — and which of them change cancer risk.

FOCUS ON
Fibrocystic change: most common, cyclic tender lumps; only atypical hyperplasia meaningfully raises risk. Fibroadenoma: young woman, mobile rubbery mass, estrogen-sensitive. Phyllodes: older, large, fast-growing, leaf-like. Intraductal papilloma: bloody nipple discharge. Fat necrosis and duct ectasia mimic cancer.
LESION
MECHANISM
FEATURES
CLUE · RISK
Fibrocystic change — nonproliferative
most common
Hormone-related cysts, fibrosis, apocrine metaplasia
Premenopausal; bilateral, cyclic tender lumpiness; "blue dome" cysts
No ↑ cancer risk
Proliferative change without atypia
Usual ductal hyperplasia, sclerosing adenosis, papillomas
Sclerosing adenosis: calcifications and firm mass that mimic cancer
Slightly ↑ risk (~1.5–2×)
Atypical hyperplasia
Atypical ductal or lobular hyperplasia — features of in-situ carcinoma but incomplete
Found on biopsy of calcifications
Moderately ↑ risk (~4–5×), both breasts
Fibroadenoma
most common benign tumor
Biphasic: proliferating stroma compressing ducts; estrogen-sensitive
Women < 35: firm, rubbery, very mobile, well-circumscribed; grows in pregnancy, shrinks after menopause
No meaningful ↑ risk
Phyllodes tumor
Stromal overgrowth with leaf-like projections into cystic spaces
Women in 50s: large, rapidly growing mass
Benign to malignant · wide excision (recurs)
Intraductal papilloma
Papillary growth in a large lactiferous duct; myoepithelial layer retained
Bloody nipple discharge; small subareolar mass; premenopausal
Usually benign · excise to exclude papillary carcinoma
Acute mastitis / abscess
S aureus enters through cracked nipples during breastfeeding
Red, warm, painful breast, fever
Keep breastfeeding · dicloxacillin/cephalexin · drain abscess
Periductal mastitis
Smoking (± vitamin A deficiency) → squamous metaplasia of lactiferous ducts → keratin plugs
Recurrent subareolar abscess, nipple retraction; non-lactating women
Fistula formation
Mammary duct ectasia
Dilated subareolar ducts with inspissated secretions, plasma cells
Multiparous postmenopausal women; green-brown nipple discharge, periareolar mass
Mimics carcinoma
Fat necrosis
Trauma, surgery, radiation → saponified fat, foamy macrophages
Firm irregular mass, calcifications, may retract skin
History of trauma; mimics carcinoma
Gynecomastia
↑ estrogen:androgen ratio
Puberty, Klinefelter, cirrhosis, testicular tumors (Leydig, hCG), drugs: spironolactone, ketoconazole, cimetidine, digoxin, marijuana, estrogens
Tender subareolar disk

Mechanism — from normal to carcinoma

Normal duct2 layers
→
Usual hyperplasiaSlight risk
→
Atypical hyperplasiaModerate risk
→
Carcinoma in situ
→
Invasive carcinomaThrough basement membrane

A preserved myoepithelial layer (p63, SMA) marks a benign or in-situ process; invasive carcinoma loses it.

Nipple discharge

DISCHARGE
THINK
NEXT
Bloody, unilateral, one duct
Intraductal papilloma (or carcinoma)
Imaging + excision
Milky, bilateral
Prolactinoma, dopamine antagonists, hypothyroidism, pregnancy
Prolactin, TSH, hCG
Green-brown, sticky
Duct ectasia, fibrocystic change
Reassure / imaging
Purulent
Mastitis, periductal abscess
Antibiotics, drainage

How it's tested

COMMON CONFUSIONFibroadenoma and phyllodes are both stromal-epithelial tumors. Fibroadenoma: young, small, mobile. Phyllodes: older, large, fast-growing, leaf-like stroma that can be malignant.
THE TRAPFat necrosis and duct ectasia can produce hard masses, skin retraction and calcifications — they still need biopsy because carcinoma does the same.
YOUR APPROACHAge + mobility + growth rate + pain/cycle + discharge type + lactation or trauma → lesion → risk category → next step.

If you see… think…

25-year-old with a firm, mobile, rubbery 2 cm mass → fibroadenoma
Bilateral tender lumpy breasts worse before menses → fibrocystic change
Biopsy with atypical ductal hyperplasia → moderately ↑ cancer risk in both breasts
55-year-old with a large, rapidly growing, leaf-like breast mass → phyllodes tumor
Bloody discharge from a single duct, small subareolar mass → intraductal papilloma
Breastfeeding woman with fever and a red painful breast → acute mastitis (S aureus)
Smoker with recurrent subareolar abscesses → periductal mastitis
Postmenopausal woman with green discharge and plasma cells around dilated ducts → duct ectasia
Firm mass after a seatbelt injury, foamy macrophages → fat necrosis
Man on spironolactone with tender breast enlargement → drug-induced gynecomastia