Updated: 12/26/2021

Lobular Carcinoma In Situ (LCIS)

Review Topic
  • Snapshot
    • A 62-year-old women presents to her primary care physician with a mass in the right breast, which she believes was the result of trauma. On exam there is a firm, fixed 1 cm mass in the right breast in the upper outer quandrant. There is no axillary lyphadenopathy.
  • Introduction
    • Overview
      • a non-invasive lesion due to proliferative changes within the breast lobule
      • not a premalignant lesion
      • considered a risk factor for breast cancer
        • if untreated LCIS will become invasive in 20-30% of patients over a prolonged period of time (10-15 years)
        • 7-11x higher risk of developing invasive breast cancer in a patient with LCIS
          • contralateral cancer can either be ductal or lobular
          • majority are estrogen and progesterone positive
  • Epidemiology
    • Incidence
      • ~10% of "malignant" lesions on mammogram
      • lifetime risk is 1% per year
    • Risk factors
      • age > 40 years
      • family history of breast cancer
      • hormone replacement therapy
    • Genetics
      • mutations
        • LCIS cells are usually estrogen/progesterone receptor-positive and HER2/neu-negative
  • Presentation
    • Symptoms
      • asymptomatic
      • breast lump
    • Physical exam
      • breast lump may be detected on exam or may not be palpable
  • Imaging
    • Mammography
      • indications
        • screening
          • regular screening for all women ≥ 40-50 years of age
          • screening of contralateral breast in LCIS patients
            • LCIS often bilateral in the same quadrant
            • need to do mammography of the contralateral breast at regular intervals
        • diagnosis of breast lump
      • findings
        • LCIS not readily visible on mammography
    • Core needle biopsy
      • indications
        • diagnosis
          • after lump or lesion detected on mammography
          • diagnosis made via histology
            • proliferation of small cells within the breast lobule with small, uniform, oval-shaped nuclei
  • Differential
    • Ductal carcinoma in situ (DCIS)
      • key distinguishing feature
        • histology
          • DCIS will show proliferation of neoplastic epithelial cells within mammary ductal system with no evidence of invasion into surrounding stroma
            • occasional overlap in LCIS and DCIS features
              • immunohistochemical staining used to differentiate
                • DCIS is positive for e-cadherin while LCIS is negative
  • Treatment
    • Medical
      • tamoxifen
        • indications
          • higher-risk patients to reduce future invasive carcinoma risk
      • close follow-up
        • frequent scheduled exams
        • mammographic screening of both breasts
    • Surgical
      • excisional biopsy
        • indications
          • high-risk patients
      • bilateral mastectomy
        • indications
          • to reduce risk of developing invasive carcinoma in ipsilateral or contralateral breast
            • in patients who have family history of premenopausal breast carcinoma
  • Complications
    • Development of invasive carcinoma
  • Prognosis
    • Very good
      • majority of women with LCIS will not develop invasive breast cancer

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