Diffuse Breast Cancer on Imaging

• There are two main groups of diffuse breast cancers:
  • That present as large areas of architectural distortion on the mammogram:
    • Neoductgenesis
    • Diffusely infiltrating carcinoma:
      • Which makes up approximately 5% of all breast cancers
• When the tumor is e-cadherin negative:
  • It is usually called invasive “lobular” carcinoma
• When it is e-cadherin positive:
  • It is called infiltrating “ductal” carcinoma
• The designation based on e-cadherin staining is arbitrary:
  • Because the behavior of diffusely invasive carcinoma:
    • Is the same regardless of the staining
• Lacking calcifications and a central tumor mass:
  • These cancers are notoriously difficult to perceive on mammogram:
    • Even when they are large and palpable or when they occur in fatty involuted breasts:
      • However, the associated connective tissue response:
        • Makes this type of cancer quite visible with ultrasound
• In contrast to diffusely infiltrating cancers:
  • Circular (Image 1) and spiculated (Image 2):
    • Tumors arising in the terminal ductal lobular units (TDLU) have:
      • Bulging, convex contours protruding into the adipose tissue
• The solid variety of infiltrating lobular carcinoma:
  • Most probably arises within the TDLU:
    • Has a circular / oval shape on breast imaging (Images 3)

Image 1: Lobulated spherical tumor mass

Image 2: Multifocal stellate invasive breast cancer

Image 3: Mammographic, MRI and pathologic images of the solid form of invasive lobular

• There are two other variants of invasive lobular carcinoma that arise in the TDLUs:
  • The tubulolobular variant:
    •  Is either a unifocal or multifocal spiculated lesion on the mammogram (Image 5)

Image 4: Mammogram and large format histology of a multifocal tubulolobular breast

• The alveolar type of invasive lobular carcinoma:
  • Is usually mammographically occult;
    • Or it can be seen as a subtle, asymmetric density (Image 5)

Image 5: Mammogram and large format histology alveolar type invasive lobular carcinoma

• The various forms of invasive lobular carcinoma that develop in the TDLUs and present as localized lesions:
  • Have a significantly better prognosis than the diffusely infiltrating type breast cancer
• Complex sclerosing lesions:
  • Present mammographically as non-palpable architectural distortion with no central tumor mass and lucent radiating structures, the so called “black star”:
    • As opposed to cancers originating from the TDLU:
      • Which have a dense central tumor mass surrounded by radiopaque spiculation, giving the impression of looking at a “white star
• Malignant phyllodes tumors:
  • Present as large, high density masses:
    • The borders may be circumscribed or ill defined
• Fat necrosis:
  • Also presents as a hypoechoic, high-density mass

• References
• Tot T. Diffuse invasive breast carcinoma of no special type. Virchows Arch. 2016;468(2):199-206.
• Tabár L, Dean PB. Teaching Atlas of Mammography. New York, NY: Thieme; 2011.
• sity mass.