Malignancy of the secretory lobules of the breast that is contained within the basement membrane

Aetiology

• Usually diagnosed before menopause

Pathophysiology

• It is not a cancer but an area of abnormal cell growth that increases a person's risk of developing invasive breast cancer later
• Much rarer than DCIS however individuals with LCIS are at greater risk of developing an invasive breast malignancy

Clinical features

• Usually asymptomatic

Investigations

• LCIS is usually asymptomatic, much like DCIS, however LCIS is not associated with microcalcifications but instead usually diagnosed as an incidental finding during biopsy of the breast

Management

• If L(is)N discovered on core biopsy - proceed to excision or vacuum biopsy to exclude higher grade lesion
• If L(is)N is discovered on vacuum or excision biopsy - followup, clinical trials

Other lobular precursor lesions

• Lobular carcinoma in situ involves >50% of lobule involved; atypical lobular hyperplasia is the term used when <50% of lobule involved