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


  • Breastfeeding women


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


  • 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


  • 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 


  • 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