Lobular carcinoma in situ

Section: Breast Curriculum: Curriculum, page 9

Definition

Non-invasive monomorphic proliferation of cells in one or more terminal lobules with characteristic features of cellular discohesion due to loss of expression of e-cadherin, eccentric nuclei and intra-cytoplasmic vacuoles

• LCIS
  • More than half the acini in a terminal duct lobular unit are filled
• ALH
  • Less than half the acini in a terminal duct lobular unit are filled

Considered to be an index of risk for invasive cancer rather than a premalignant lesion

Incidence

• Unknown
• Almost always found incidentally

Histology

• Lobular neoplasia encompasses a spectrum of lesions including Atypical lobular hyperplasia (ALH) and Lobular carcinoma in situ (LCIS)
  • Both comprise the characteristic features
    • Neoplastic monomorphic cells with
      • Cellular discohesion
        • Due to loss of e-cadherin protein
      • Eccentric nuclei
      • Intra-cytoplasmic vacuoles
    • Pagetoid pattern of proliferation
    • Signet ring cells
• Three types of LCIS
  • Classical
  • Non-classical
    • Pleomorphic
      • Larger cells with marked nuclear pleomorphism
      • Often have central necrosis
    • Florid
      • Marked duct distension
      • Can become mass forming
      • Often with central necrosis

Management

• Classical
  • Observe
• Non-classical
  • Treat like DCIS
  • Surgical excision with re-excision to negative margins

Future risk

• 7-11x
  • Overall risk: 1% / year
• Risk reduction
  • Stop oral contraceptive, avoid HRT, life style and diet choices
  • Active surveillance
    • Lifetime
    • Yearly mammogram
  • Chemoprevention
    • Tamoxifen or Aromatase inhibitors
  • Bilateral prophylactic mastectomy is an infrequently taken option, but could be suggested if pt has high risk circumstances (BRCA 1 or 2, strong FHx)