Microinvasive breast carcinoma is defined as invasive carcinoma of the breast with no invasive focus measuring more than 1 mm . It is almost always encountered in the setting of ductal carcinoma in situ (DCIS); thus, it is commonly referred to as ductal carcinoma in situ with microinvasion. It is less commonly seen in association with lobular carcinoma in situ (LCIS) or in the absence of noninvasive disease.
The epidemiology, clinical presentation, pathology, and treatment of microinvasive breast carcinoma will be reviewed here. DCIS and LCIS are presented separately.
Data about the epidemiology and clinical significance of microinvasive breast carcinoma has been limited by its uncommon incidence and the historical lack of a standardized definition.
Epidemiology — The incidence of microinvasive breast carcinoma appears to have increased in parallel with the rising incidence of ductal carcinoma in situ (DCIS), which has been attributed primarily to the introduction of breast cancer screening programs as well as more thorough sampling of breast tissue specimens. In a retrospective cohort review of 205 consecutive patients with DCIS, 51 (24.9 percent) patients had microinvasion identified upon histologic examination .