adenosis is a rare proliferative lesion of the breast that may mimic carcinoma grossly and histologically. Although the lesion in its simplest form is benign, it can give rise to carcinoma, which may be found at the time of diagnosis in a minority of cases. Limited follow-up data have indicated no predisposition to develop subsequent carcinoma in patients treated with excisional biopsy for microglandular adenosis when carcinoma was not initially present. Breast conservation has rarely been used in patients with carcinoma arising in microglandular adenosis. We report here the unique 10-year follow-up of a woman who underwent breast conservation treatment for carcinoma that arose in microglandular adenosis.