<aside> Breast neoplasms are benign or malignant proliferations of breast tissue, with breast carcinoma being the most common malignancy in women worldwide. They arise from epithelial, stromal, or mixed tissue components and range from non-invasive lesions to invasive cancers.

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Etiopathogenesis

Genetic factors: BRCA1/2, TP53, PTEN mutations.
Hormonal influences: prolonged estrogen exposure (early menarche, late menopause, nulliparity, hormone replacement).
Environmental/lifestyle factors: obesity, alcohol, radiation exposure.

Pathogenesis of carcinoma:

Genetic mutations → loss of tumor suppressor function / oncogene activation.
Progression from ductal/lobular hyperplasia → atypical hyperplasia → carcinoma in situ → invasive carcinoma.

Classification

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WHO Tumor Classification (5th edition)

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Benign Breast Neoplasms

Fibroadenoma	Most common benign tumor; well-circumscribed, mobile, in young women.
Phyllodes tumor	Fibroepithelial, can be benign, borderline, or malignant.
Papilloma	Intraductal, often causes nipple discharge.
Others (rare)	Lipoma, hamartoma, hemangioma

Malignant Breast Neoplasms

Carcinoma in situ	DCIS (Ductal carcinoma in situ)	Confined to ducts, microcalcifications common.
	LCIS (Lobular carcinoma in situ)	Marker of increased bilateral cancer risk.
Invasive Carcinomas	Invasive ductal carcinoma (IDC)	Most common (~70–80%). Hard irregular mass, desmoplastic reaction.
	Invasive lobular carcinoma (ILC)	~10–15%, more often bilateral/multicentric, “single-file” histology.
	Others	Tubular, mucinous, medullary, metaplastic carcinoma.
Special Malignant Neoplasms	Paget disease of the nipple	Eczematous changes due to DCIS extending into nipple skin.
	Inflammatory breast carcinoma	Rapid onset erythema, peau d’orange, dermal lymphatic invasion.
	Sarcomas	Angiosarcoma, phyllodes tumor (malignant variant).
	Metastases	Rare, often from melanoma, lung, ovary.

Clinical Features

Painless lump (most common).
Nipple changes: retraction, discharge.