Wednesday, March 15, 2017

Malignant Breast Disease

This post is derived from notes I took during training. Any images are copyright their respective owners.

  • Most invasive cancers arise from the terminal ductal lobular unit, which contain 100 acini draining into a terminal duct
    • Each breast has 15-18 lobes, each with 20 - 40 lobules
  • Ductal carcinoma in situ (DCIS)
    • Most common subtype
    • Findings: fine, linear, branching ca++ (BIRADS 5)
    • Prognosis: If untreated, 1% per year become invasive
  • Invasive Ductal Carcinoma (IDC)
    • MG: High density, spiculated mass with architectural distortion +/- pleomoprhic or fine linear branching ca++
  • Invasive lobular carcinoma (ILC)
    • Pathology: small monomorphic cells infiltrating stroma single file
    • Difficult to diagnose (21% MG false negative rate) because of infiltrating pattern
    • Findnigs: Spiculated ill-defined mass with architectural distortion; up to ⅓ are bilateral or multicentric (ie, exam contralateral breast well). Ca++ rare.
  • Phyllodes (cystosarcoma phyllodes)
    • Women 40-50s, with large, rapidly growing mass
    • Majority benign, but 25% malignant
    • MG: large, oval or lobular, circumscribed mass
    • US: smoothly marginated mass with heterogeneous echotexture
    • Treatment: wide surgical excision, often recurs
  • Tubular breast carcinoma
    • Pathology: low grade - proliferation of angulated, oval and elongated tubules lined by a single epithelial layer. Spreads through tissue without forming discrete mass - harder to diagnose. Difficult for pathologist to differentiate from radial scar (? spectrum)
    • Findings: small, irregularly shaped, spiculated margins, slow growing
  • Mucinous breast carcinoma
    • Findings: Low density circumscribed mass that can mimic fibroadenoma on US.
    • MR: T2↑
  • Medullary carcinoma
    • Younger women, rare, BRCA1 positive, locally aggressive
  • Papillary breast carcinoma
    • Malignant form of intraductal papilloma
    • Findings: well-circumscribed mass, most likely breast cancer to be associated with a cyst (called intracystic papillary carcinoma)

  • Adenoid cystic breast carcinoma
    • Very rare breast cancer presenting as palpable firm mass. Prognosis good
  • Inflammatory breast carcinoma
    • Presents with breast erythema, edema, firmness
    • Tumor invasion of dermal lymphatics
    • MG: affected breast larger, denser, skin thickening.
  • Lymphoma of the breast: Presents with palpable mass. DLBCL. DI: mass with indistinct margins. Treatment: Chemothearpy / radiation, not surgery
  • Paget disease of nipple:
    • DCIS that infiltrates epidermis of nipple, presents with erythema, ulceration, eczematoid changes
    • Palpable mass worsens prognosis
    • Treatment: breast conservation possible
  • Staging
    • I: Tumor less than 2 cm, negative lymph node (LN)
    • IIA: tumor 2 to 5 cm, negative LN
    • IIB: tumor 2 to 5 cm with ipsilateral LN *OR* >5 cm with neg LN
    • IIIB: any size involving chest wall +/- LN
  • Lymph nodes: based on relationship to pec minor
    • Level 1: lymph nodes lateral to pectoralis minor
    • Level 2: lymph nodes behind the pectoralis minor and interpectoral (Rotter's) nodes
    • Level 3: lymph nodes medial to pectoralis minor
    • Internal mammary chain lymph nodes are not included in this classification.
  • Breast cancer recurrences that occur within 3 yrs (75%) are most likely within original tumor bed; long-term risk 2% for first 10 years, then 1% per year after; mean time to recurrence is 3.5 yrs; most risk: pre-menopausal women with invasion, positive margins, multicentric



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