Galactocele

Galactoceles are milk-filled cysts. The term “galactocele” is derived from the Greek words galatea (milky white) and cele (pouch).

Epidemiology

• Breastfeeding women

Pathogenesis

• Unknown
• Inspissated milk within ducts may be responsible
• Mammary duct obstruction in the lactating breast resulting in proximal focal ductal dilatation

History

• Usually occurs after lactation cessation or when feeding has significantly declined 
• Can occur 6 – 10 months after breastfeeding cessation
• Painless breast mass

Physical Exam

• Breast mass
• Mass characteristics
  • Round
  • Well circumscribed
  • Mobile 
  • Nontender
  • Firm
• Usually located in central portion of breast or under the nipple

Imaging

• Breast US: solitary, well-defined, anechoic lesion with thin, echogenic walls and some distal acoustic enhancement
• Needle aspiration
  • Fluid
    • Thick, creamy material; may be tinged dark green or brown
    • Sterile
  • Often diagnostic and therapeutic 

Treatment

• Confirm diagnosis with large bore needle aspiration and withdrawal of thick milky secretion
• Surgery: only for cysts that can’t be aspiration or infected breast cysts

Relevant Information

• Breast anatomy
  • Lies between subdermal layer of adipose tissue and superficial pectoral fascia
  • Cooper ligaments
    • Provide structural support and shape (anchored into the skin)
    • Infiltration by tumors can produce tethering, resulting in dimpling on the breast tissue
• Lymphatics
  • Lymph nodes
    • Level 1: located lateral to the lateral border of the pectoralis minor muscle
    • Level II: located posterior to the pectoralis minor muscle as well as anterior to the pectoralis minor and posterior to the pectoralis major (Rotter or interpectoral nodes)
    • Level III: located medial to pectoralis minor muscle and include subclavicular nodes
  • Most drains to axillary nodes (97%)
  • Any quadrant can drain into internal mammary nodes
  • Supraclavicular nodes → N3 disease
  • Primary axillary adenopathy → ≤ 1 is lymphoma
• Nerves
  • Long thoracic nerve
    • Innervates serratus anterior muscle 
    • Injury → winged scapula 
    • Lateral thoracic artery supplies serratus anterior muscle
  • Thoracodorsal nerve
    • Innervates latissimus dorsi muscle
    • Injury → weak arm pull-ups and adduction
    • Thoracodorsal artery supplies latissimus dorsi
    • Arises from posterior cord of brachial plexus; enters axillary space under axillary vein (close to long thoracic nerve)
  • Medial pectoral nerve: innervates innervates pectoralis major and pectoralis minor muscles
  • Lateral pectoral nerve: innervates pectoralis major muscle
  • Intercostobrachial nerve
    • Lateral cutaneous branch of second intercostal nerve
    • Sensation to medial arm and axilla
    • Most common injured nerve with modified radical mastectomy (MRM) or axillary lymph node dissection (ALND)
• Arterial supply: branches of
  • Internal thoracic (mammary) artery
  • Intercostal arteries
  • Thoracoacromial artery
  • Lateral thoracic artery
• Batson’s plexus: valveless vein plexus, allows direct hematogenous metastasis of breast cancer to spine
• Costoclavicular ligament (Halsted ligament): defines axilla apex
• Breast development
  • Formed from ectoderm milk streak
  • Hormone influence
    • Estrogen: duct development (double layer of columnar cells)
    • Progesterone: lobular development
    • Prolactin: synergizes estrogen and progesterone
    • Cyclic changes
      • Estrogen → increased breast swelling, growth of glandular tissue
      • Progesterone → increased maturation of glandular tissue, withdrawal causes menses
      • FSH, LH surge → ovum release
      • After menopause, less estrogen and progesterone results in atrophy of breast and vulvar tissue
• Microscopic anatomy
  • Three tissue types
    • Glandular epithelium
      • Branching system of ducts arranged in a radial pattern extending from the nipple-areolar complex
      • Each major duct has branches and ultimately ends in terminal ductules or acini (acini are milk-forming glands of lactating breasts)
    • Fibrous stroma and supporting tissues
    • Adipose tissue 
  • Basement membrane
    • Contains laminin, type IV collagen, proteoglycans
    • Differentiates in situ from invasive breast cancer

Differential Diagnoses

• Breast cyst
• Breast fibroadenoma
• Breast abscess
• Breast cancer