CARCINOMA OF THE BREAST ARISING IN MICROGLANDULAR ADENOSIS

Breast carcinoma arose in or in conjunction with microglandular adenos is (MGA) in 14 of 60 (23%) patients with MGA listed in the authors' fi les. This article describes the clinicopathologic and immunohistochemi cal features and prognosis of these carcinomas. The median patient age was 47 years (range, 26-68 years). All patients had a mass. Six (43%) had a family history of breast carcinoma. Lymph node metastases were found in 3 of 11 axillary dissections. Ten patients treated by mastect omy were recurrence-free, with a median follow-up of 57 months (range, 3-108 months). Two of three patients treated by excisional surgery we re recurrence-free 12 and 105 months later. The third woman had bone m etastases at 51 months and was alive 98 months after treatment. Carcin oma arose in the MGA in 13 patients. In these patients, in situ carcin oma was found in expanded MGA glands composed of cells with vesicular poorly differentiated nuclei. One patient with benign MGA had carcinom a develop in the opposite breast that was not associated with MGA. Whe n it arose in MGA, basement membranes were present in benign MGA and i n situ carcinoma but tended to be disrupted in invasive foci that appe ared to be formed by coalescent MGA glands. Strong immunoreactivity fo r cytokeratin, S-100, and cathepsin D was detected in carcinomas. Two carcinomas had nuclear progesterone receptors, and one of these had es trogen receptors. One carcinoma had positive findings for HER-2neu, an d four had immunoreactivity for p53 protein. The following conclusions were drawn from these observations: (1) carcinomas arising in MGA hav e a distinctive histopathologic pattern; (2) the carcinomas are compos ed of epithelial cells (cytokeratin positive, actin negative) that are strongly immunoreactive for S-100 protein and cathepsin D; and (3) wi th a median followup of nearly 5 years, patients with these carcinomas had a relatively favorable prognosis, despite histopathologic and imm unohistochemical features usually associated with a poor prognosis.