High risk lesions:

• Atypical ductal hyperplasia (ADH)

• Atypical lobular hyperplasia (ALH)

• Lobular carcinoma in-situ (LCIS)

• Flat epithelial atypia (FEA)

• Proliferation of uniform epithelial cells w/ monomorphic round nuclei filling part of the involved duct or the entire duct but measuring <2 mm or involving <2 ducts

• Shares cytologic and architectural features w/ low-grade DCIS but is limited in extent. 

• After core bx recommend surgical excision

  • Ugraded to DCIS or IDC 10-20% of the time

  • Increased risk at site for DCIS/IDC (want clean margins)

• Marker of elevated risk for breast CA at site and in contralateral breast

  • One study showed only 60% of subsequent cancers occurred in the ipsilateral breast

• Just fills lobule. 

• Shares features with LCIS but lesser in extent. 

  • Similar to relationships of ADH and DCIS in that it is an atypical precursor to the in situ disease but differs in extent of involvement. 

• Proliferation of monomorphic, evenly spaced, dyshesive cells filling, but not expanding, the involved lobule.

• Usually found on core bx performed for other reason

• Upgrade rate on excision is very low (<3%)

• Incidental ALH does not require excision

• Confers a relative risk  of approx 4x that of a patient w/o atypia

  • Some studies show increased risk compared to patient w/ ADH

• Risk is generalized and not just at the site of atypia (can occur in the ipsilateral breast)

• Noninvasive lesion arising from the lobules and terminal ducts of the breast.

• Magnitude of association of LCIS w/ invasive breast CA is significantly greater than w/ ALH

• 2 forms

  • Classic: 

    • Solid proliferation of small cells w/ small, uniform, round to oval nuclei and distinct borders

    • Cells demonstrate cytologic dyshesion 

  • Nonclassic

    • Pleomorphic LCIS: larger cells demonstrating marked nuclear pleomorphism but otherwise same characteristics as classic LCIS. More often demonstrates central necrosis and calcs.

    • Florid LCIS: marked distension of the involved ducts and lobules by the cells of classic LCIS and the lesion becomes mass forming. Often demonstrates comedo-pattern necrosis.

• Management:

  • After core bx, surgical excision is recommended for any nonclassic LCIS or LCIS w/ imaging pathologic discordance. Incidental classic LCIS does not require excision.

  • If nonclassic LCIS is diagnosed on excision

    • Evaluation of margins for LCIS is recommended

    • If nonclassic LCIS seen at margins -> reexcision is recommended

• LCIS and future CA risk

  • Relative risk of developing invasive cancer in women w/ LCIS is approx 7 to 11-fold higher than those without it.

  • Risk assessment and close surveillance is recommended. Prophylactic b/l mastectomy is rarely considered.

• Columnar cells change w/ atypia

• Neoplastic alteration of the DLU characterized by replaceent of the native epithelial cells by 1 to several layers of a single epithelial cell type showing low-grade cytologic atypia. 

• Upgrade rate after core bx is 0-5%

  • Most studies show if no residual calcification post bx, excision is not necessary.