Lecture Notes: Breast Pathology

Introduction

• Presented by Dirty Medicine
• Focus on tools to answer questions, not pathophysiology
• Categories: Inflammatory, Benign, Malignant conditions

Categories of Breast Pathology

1. Inflammatory Conditions
   • Mastitis
   • Mammary Duct Ectasia
   • Fat Necrosis of the Breast
2. Benign Conditions
   • Fibrocystic Changes
   • Intraductal Papillomas
   • Fibroadenomas
   • Phylodes Tumor
3. Malignant Conditions
   • Ductal Carcinoma In Situ
   • Invasive Ductal Carcinoma
   • Lobular Carcinoma In Situ
   • Invasive Lobular Carcinoma

Inflammatory Conditions

Mastitis

• Inflammation of the breast parenchyma
• Common in breastfeeding mothers due to Staph aureus
• Symptoms: Warm, swollen, tender breast
• Treatment: Dicloxacillin, analgesics, compresses; continue breastfeeding

Mammary Duct Ectasia

• Subareolar periductal inflammation with dilated ducts
• Buzzword: Greenish-brown nipple discharge
• Mnemonic: Oregon Ducks (green/brown discharge)

Fat Necrosis of the Breast

• Non-viable adipose tissue replaced by scar tissue
• Associated with trauma or surgery
• Buzzwords: Multinucleated giant cells, calcifications
• Mnemonic: Cheese analogy (giant block of cheese)

Benign Conditions

Fibrocystic Changes

• Most common benign breast pathology in premenopausal women
• Subtypes:
  • Apocrine Metaplasia: No risk
  • Sclerosing Adenosis: Some risk
  • Atypical Hyperplasia: Significant risk
• Mnemonic: Apok, Sclerosing equals some, Atypical can a turn into cancer

Intraductal Papilloma

• Papillary growth within large duct epithelial cells
• Buzzword: Bloody nipple discharge, fibrovascular projections
• Key difference from papillary carcinoma: Presence of myoepithelium
• Mnemonic: Included myoepithelium

Fibroadenomas

• Most common breast tumor in women under 35
• Estrogen-sensitive
• Mnemonic: Fibroadenomas are estrogen sensitive

Phylodes Tumor

• Ranges from benign to malignant
• Buzzword: Leaf-like projections
• Mnemonic: Leafy-like for phyllodes

Malignant Conditions

Ductal Carcinoma In Situ (DCIS)

• Proliferation within ducts, not invaded basement membrane
• Buzzword: Calcifications
• Mnemonic: DCS (Dem Calcifications)

Invasive Ductal Carcinoma

• DCIS through basement membrane
• Subtypes:
  • Medullary: Sheet-like growth, lymphocytic infiltrate
  • Inflammatory: Dermal lymphatic invasion, peau d'orange appearance

Lobular Carcinoma In Situ (LCIS)

• Proliferation in lobules, not invaded basement membrane
• Lacks e-cadherin
• Mnemonic: LC lacks cadherin

Invasive Lobular Carcinoma

• LCIS through basement membrane
• Buzzword: Non-cohesive cells, single file pattern
• Mnemonic: ILC, Individual Line Carcinoma

Conclusion

• Focus on mnemonics and high-yield points for exams
• Emphasis on understanding and memorizing key facts