Breast
Inflammatory
Duct ectasia


Topic Completed: 20 February 2020

Minor changes: 20 April 2020

Copyright: 2012-2020, PathologyOutlines.com, Inc.

PubMed Search: Duct ectasia of breast [title]

Carlos C. Diez Freire, M.D.
Shahla Masood, M.D.
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Cite this page: Diez Freire C, Masood S. Duct ectasia. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/breastductectasia.html. Accessed December 4th, 2020.
Definition / general
  • Mammary duct ectasia is a disorder of the extralobular ducts
  • Is characterized by different degrees of periductal inflammation, periductal fibrosis and duct dilatation
  • Foamy histiocytes are typically present within the luminal secretions and infiltrate the wall of the involved ducts
Essential features
  • Foamy histiocytes within luminal secretions and within wall and epithelium of involved ducts
  • Periductal inflammation, can be plasma cell heavy
  • Periductal fibrosis in late stages
Terminology
  • Also called mastitis obliterans and comedo mastitis, although these terms have not been as widely used as duct ectasia
ICD coding
  • ICD-10: N60.49 - mammary duct ectasia of unspecified breast
Epidemiology
  • Usually women in perimenopausal and postmenopausal age
  • It can occur in neonates
Sites
  • Extralobular ducts; retro areolar, can be bilateral
Etiology
  • Not well known
  • Some authors believe that involution seen in postmenopausal women is the primary pathologic process (gland atrophy → stasis of secretions → leakage of lipid rich material through duct wall → periductal inflammation)
  • Other authors believe that periductal inflammation is the inciting process that is followed by duct sclerosis, obliteration and finally ectasia
  • Stasis caused by duct obstruction is considered by some to be the inciting cause of duct inflammation with further obstruction, stasis and dilatation as observed in cases of squamous metaplasia of lactiferous ducts (SMOLD)
  • Smoking, phenothiazine treatment and hyperprolactinemia have been postulated as possible causes (Hoda: Rosen's Breast Pathology, 4th Edition, 2014)
Clinical features
Case reports
Treatment
  • Circumareolar incision and removal of the affected duct and fistula tract, if present, is the treatment of choice
Gross description
Microscopic (histologic) description
  • Dilation of ducts with foamy histiocytes within the luminal secretions and infiltrating the wall of the involved ducts
  • Periductal inflammation with lymphocytes, plasma cells, neutrophils and histiocytes; these can become multinucleated in cases of duct rupture due to reaction to spilled secretions in the stroma
  • Periductal fibrosis with obliteration of the duct’s lumen can also be seen (garland sign)
Microscopic (histologic) images

Contributed by Carlos C. Diez Freire, M.D.
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Dilated ducts with foamy macrophages


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Dilated ducts with foamy macrophages

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Garland sign

Cytology description
  • Thick cheesy secretion composed of amorphous material and cellular debris that resembles necrosis
  • Amorphous material may have a crack artifact as seen in watery thyroid colloid
  • Small crowded groups or sheets of ductal cells with reactive atypia may be present
  • The inflammatory component has plasma cells (can be abundant), neutrophils and foamy macrophages that can have pigment
  • Giant cells, calcifications and cholesterol clefts can also be present (DeMay: Art and Science of Cytopathology, Volume 2, Superficial Aspiration Cytology, 2nd Edition, 2012)
Positive stains
  • CD68 highlights luminal and subepithelial histiocytes
Sample pathology report
  • Left breast, 2 o’clock, 5 cm from nipple, ultrasound guided core biopsy:
    • Duct ectasia
Differential diagnosis
  • Breast abscess:
    • Presence of severe acute inflammatory infiltrate
    • Often associated with lactation
  • Ductal carcinoma in situ:
    • Neoplastic epithelial cells confined to the mammary ductal lobular unit
    • Can have expansive comedo type necrosis
Board review style question #1

    Which of the following is true about the breast entity depicted above?

  1. Increases the risk of invasive ductal carcinoma
  2. Is always a unilateral process
  3. Most commonly affects the extralobular ducts in the retro areolar region
  4. Most frequently affects men and children
Board review answer #1
C. Extralobular ducts; retro areolar region, can be bilateral. The photo depicts duct ectasia.

Comment Here

Reference: Duct ectasia of breast
Board review style question #2
    Mammary duct ectasia is characterized by which of the following microscopic findings?

  1. Dilation of ducts with foamy histiocytes within the luminal secretions and infiltrating the wall of ducts with periductal inflammation
  2. Epithelial proliferation that fills and distends the terminal duct lobular units
  3. Infiltrating ductal proliferation with desmoplastic stromal response
  4. Proliferation of both stromal and glandular elements
Board review answer #2
A. Dilation of ducts with foamy histiocytes within the luminal secretions and infiltrating the wall of ducts with periductal inflammation

Comment Here

Reference: Duct ectasia of breast
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