Breast masses

Invasive Lobular Carcinoma (ILC)

• Infiltrated breast like spiderweb causing thickening without central mass
• More difficult to detect
• 6-9% of breast cancer
• Shrinking breast appearance on mammogram due to loss of elasticity
• Differential includes radial sclerosis (radial scar)
• Ultimately need surgical excision, but core biopsy may aid in sugical planning

Invasive ductal carcinoma Not Otherwise Specified (IDC NOS)

• IDC NOS and Ductal carcinoma in situ (DCIS) account for 85% of breast cancers
• IDC NOS presents as a spiculated or irregular mass or as a new focal asymmetry

Well Differentiated Subtypes of IDC

• Overall better prognosis than IDC NOS
• Mucinous
  • Low density oval, circumscribed mass containing mucin
  • High T2 signal on MRI
• Medullary
  • Round mass with ill defined boarders
  • Well circumscribed carcinoma composed of poorly differentiated cells with scant stroma and prominent lymphoid infiltration
• Tubular
  • Appears spiculated
  • Excellent prognosis (tubular = cool)
  • Can be slow growing
• Papillary
  • Round intraductal or intracystic mass
  • Often present with nipple discharge
  • Cannot differentiate papilloma from papillary carcinoma on imaging alone

Peanut M&Ms - Papillary, Medullary and Mucinous are all round on Mammo/US

Cancers of Stromal Origin

• Phyllodes
  • Mimics fibroadenoma, except on US with ill defined margins
  • Large in size (>3cm)
  • Middle-aged and older women

• Angiosarcoma
  • Ill defined vascular mass
  • Can be secondary to radiation therapy

• Osteosarcoma - calcified mass
• Adenoid Cystic Carcinoma - arises from secretory glands

Metastasis

• Most common are: lymphoma, melanoma, rhabdomyosarcoma, lung, ovarian, renal cell, cervical

Unusual Breast Cancers: Useful Clues to Expanding the Differential Diagnosis