Noninvasive carcinoma of the breast presenting in adenosis

Although sclerosing adenosis is a common abnormality in the female breast, malignant change presenting in this setting is exceedingly rare, as fewer than 20 cases have been reported. Since sclerosing adenosis is a lesion of the mammary lobule, it is not surprising that the majority of reported cases have been lobular carcinoma in situ (LCIS). Nine patients with noninvasive carcinoma, restricted in the initial biopsy specimen to foci of sclerosing adenosis, are reported. Seven of the patients had LCIS, one had intraductal carcinoma (DCIS), and one had both LCIS and DCIS. In six of the nine patients, the carcinoma was an incidental finding in a breast biopsy performed for fibrocystic changes or for a fibroadenoma, and in three patients, the abnormality presented as a grossly discrete lesion due to confluence of foci of adenosis (tumoral adenosis). It is important to recognize this microscopic pattern of neoplasia to prevent its misdiagnosis as invasive carcinoma. Two patients had no further treatment following initial excisional biopsy. No residual carcinoma was found in the breast or in lymph nodes in the four patients who had mastectomy. Eight of these patients have been followed for an average of 3 yr (range, 2 to 7 yr), and all are alive and well, without recurrence. Because of the possibility of multifocality, the rarity of the lesion, and the relatively brief follow-up interval, it seems prudent to treat these patients in a manner comparable to that of patients with more common presentations of noninvasive carcinoma.