BENIGN PROLIFERATIVE BREAST DISEASE

• This is a benign breast tumour composed of new fibrous + glandular tissue. It affects young people (20-35)
• Macroscopy: firm mass, cut surface: sharply demarcated, gray-white.
• Microscopy: glands present lined by cuboidal/low columnar cells & are surrounded by stroma (fibrous tissue). Glands appear distorted as stroma compresses them.
• Risk of breast Ca: 0.1% cases progress to malignancy.
  

• Papillomas are tumours that extend into the lumen of ducts. Two types: 1) small duct, 2) large duct (bloody nipple discharge).
• Macroscopy: palpable mass in some cases only
• Microscopy: central core of fibrovascular tissue surrounded by 2 cell epithelial layer.
• Risk of breast Ca: depends on the microscopic appearance. If: presence of 2 cell layer, lack of cribiform/trabecular pattern, low mitotic activity etc --> benign.
  

• This is a disease where the stroma becomes increasingly fibrotic and there are cysts within the breast. The pathogenesis is related to hormonal imbalances.

• Macroscopy: numerous microcysts + large cysts

• Microscopy: Components are:
  
• 1) Cysts: cystic dilatation of lobules and ducts produces numerous cysts,
  
• 2) apocrine metaplasia: cysts are lined by cells that look like those in apocrine sweat glands: polygonal cells, abundant granular cytoplasm, central nucleus,
  
• 3) Fibrosis: cysts rupture and release their contents --> result in chronic inflammation --> scarring/fibrosis of stroma,
  
• 4) epithelial hyperplasia: papillary projections of epithelium are common,
  
• 5) sclerosing adenosis: number of acini per lobule is increased 2 fold and the stroma compresses the glands distorting them --> mimicks Ca --> but staining for myoepithelial cells is reassuring.

• Usually the epithelium of ducts are 2 layers (columnar + myoepithelial cells). In this disease there is hyperplasia of epithelium --> more than 2 layers present. > 4 layers = increased risk of Ca but most often not.
• Microscopy: The lumen is filled with populations of epithelial cells, leaving uneven fenestrations. If fenestrations are more regular/even --> more chance that is atypical.
  
• In addition: look for signs of atypicalness: hyperchromatic nuclei, loss of polarity, regular spaces, absence of myoepithelial cells etc.
  

Category: Pathology Notes