Mammary Duct Ectasia

Definition

• A subareolar periductal chronic inflammatory process that in early stages is characterized by dilated ducts but eventually produces ductal obliteration

Alternate/Historical Names

• Cholesterol granuloma
• Comedomastitis
• Mastitis obliterans
• Plasma cell mastitis
• Periductal mastitis

Diagnostic Criteria

• Early lesions
  • Centered on subareolar ducts
    • May spread
  • Dilated ducts may contain:
    • Foamy histiocytes
      • Polyps containing histiocytes have been reported as "lipophagic polyps"
    • Proteinaceous secretion
    • Cholesterol crystals
    • Calcification
  • Periductal inflammation
    • Circumferential
    • Lymphocytes, plasma cells and histiocytes
    • May contain foreign body giant cells (granulomatous periductal mastitis)
    • Plasma cells when prominent have lead to the designation of the lesion as “plasma cell mastitis”
  • May form abscess or fistula
  • Epithelium usually atrophic
    • May show squamous metaplasia
    • May be replaced by granulation tissue
  • Periductal fibrosis
• Late lesions
  • Sclerosis may lead to duct obliteration
    • Termed “mastitis obliterans”
    • Elastic tissue stain may be used to demonstrate presence of obliterated duct
  • Recanalization around the periphery of ducts by small tubules
    • Termed “garland pattern”
  • Epithelium may be totally destroyed
• May be a secondary change associated with nearby intraductal papilloma

Richard L Kempson MD
Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342

Original posting:: May 27, 2006

Supplemental studies

Immunohistochemistry

• Foamy cells stain as expected for histiocytes:
  • Positive: CD68, CD163, HAM56, MAC387, lysozyme, alpha-1-antitrypsin
  • Negative: LCA, keratin

Differential Diagnosis

Granulomatous Lobular Mastitis	Mammary Duct Ectasia
Centered on lobules	Centered on ducts
Granulomatous inflammation	May have giant cells but usually lacks formed granulomas
Nearly all cases postpartum	May occur without associated pregnancy

Clinical

• Bacteria can be cultured in many cases and in all cases with abscess or fistula formation
  • The role played by bacteria in uncomplicated cases is not clear
  • Nevertheless, antibiotic treatment is usually given
• Most common in childbearing ages
  • Rare cases are reported in males and in patients as young as infants
• No relationship to parity or breast feeding
• Presents with nipple discharge, may be bloody
• Variably present:
  • Mass
  • Pain
  • Nipple retraction
• Has been reported associated with prolactin secreting pituitary adenomas

Lists

Inflammatory and Infectious Breast Lesions

• Granulomatous lobular mastitis
• Mammary duct ectasia
• Puerperal mastitis
• Specific infectious processes
  • Bacteria
    • Bartonella henselae (cat scratch disease)
    • Corynebacteria
  • Fungi
    • Actinomycosis
    • Blastomycosis
    • Cryptococcosis
    • Histoplasmosis
  • Mycobacterium tuberculosis
• Vasculitis
  • Giant cell arteritis
  • Polyarteritis nodosum
  • Wegener granulomatosis

Bibliography

• Rosen PP, Oberman HA. Tumors of the Mammary Gland, Atlas of Tumor Pathology, AFIP Third Series, Fascicle 7, 1993
• Garijo MF, Val-Bernal JF, Sanchez-Larrauri S. Multiple ductal lipophagic polyps of the breast: a rare finding in mammary duct ectasia. Histopathology. 1997 Nov;31(5):480-1.
• Bundred NJ, Dixon JM, Lumsden AB, Radford D, Hood J, Miles RS, Chetty U, Forrest AP. Are the lesions of duct ectasia sterile? Br J Surg. 1985 Oct;72(10):844-5.
• Browning J, Bigrigg A, Taylor I. Symptomatic and incidental mammary duct ectasia. J R Soc Med. 1986 Dec;79(12):715-6.
• Dixon JM. Periductal mastitis/duct ectasia. World J Surg. 1989 Nov-Dec;13(6):715-20.
• Dabbs DJ. Mammary ductal foam cells: macrophage immunophenotype. Hum Pathol. 1993 Sep;24(9):977-81.