Editing LCIS

A non-invasive lesion that arises from the lobules and terminal ducts of the breast.

== Pathophysiology ==

* Recognised by its conformity to the outline of the normal lobule, with expanded and filled acini
* Variant - pleomorphic LCIS - a distinct, more aggressive subtype
** Shows nuclear pleomorphism compared with classic LCIS
** One or more lobules are distended by discohesive cells with irregularly-shaped, high-grade nuclei
** May or may not be associated with comedonecrosis and calcifications
** Controversial, but some suggest it should be excised and treated like DCIS
* Florid LCIS is another more aggressive variant

== Presentation ==

* Uncommon condition, predominantly seen in younger pre-menopausal women
* Often found incidentally on biopsy 
* Does not manifest as palpable mass or microcalcifications on mammography

== Treatment ==

* If found incidentally:
** If core biopsy only shows classic LCIS, and radiology is concordant, observe with clinical and imaging follow-up. Very low upgrade rates (<3%).
** Pleomorphic or florid LCIS should be excised to negative margins.
* Treatment options
** Close surveillance
*** Annual mammography and consider annual MRI (ideally, alternate these every 6 months)
** Chemoprevention
*** Significant risk reduction with SERMs or Ais (reduces 5-year risk of invasive cancer by about 50%)
** Bilateral mastectomy
*** 90-95% risk reduction
*** Consider for women with additional risk factors 

== Prognosis ==

* Typically thought of as a marker of increased risk of developing breast cancer in the future, however this is controversial
* Not currently considered to be a preinvasive breast cancer
* Estimated lifetime risk of developing breast cancer is 30-40% (applies to both breasts, but higher risk in ipsilateral breast). Sabiston quotes actuarial risk of getting cancer within 35 years of 21.4%.
* RR of 7 for breast cancer
* 40% of cancers subsequently developing in patients with LCIS were in situ lesions. The invasive cancers that DID develop were predominantly ductal and not lobular, and 50% occurred in the contralateral breast.

[[Category:Breast]]