Cystic hypersecretory hyperplasia and cystic hypersecretory duct carcinoma of the breast. Pathology, therapy, and follow-up of 39 patients.

The study documented in this article was performed to define the clinical and morphologic features of cystic hypersecretory carcinoma (CHC) and cystic hypersecretory hyperplasia (CHH) of the breast. Both lesions are characterized by the formation of cystically dilated ducts containing a homogeneous eosinophilic secretion that resembles thyroid colloid. In most cases CHC features micropapillary intraductal carcinoma, occasionally giving rise to a high-grade, invasive carcinoma that is absent from CHH. Electron microscopy of the cystic component in one case of CHC showed ultrastructural characteristics of metabolically active cells, but few secretory granules. Twenty-nine patients with CHC were observed for up to 23 years. Twenty-five women who had intraductal carcinoma were well or died of other causes. Of the four patients who had invasive carcinoma, one died 9 months after being diagnosed as having systemic metastases, and the other three remained disease-free. Ten cases of CHH were reviewed; follow-up information was available for eight patients for up to 5 years. Six women were alive and well. One woman died of contralateral invasive carcinoma, and a second was well having had a modified radical mastectomy for a separate, coexisting intraductal carcinoma in the same breast. These findings indicate that intraductal CHC has the same low-grade clinical course as other forms of intraductal carcinoma. Because invasive carcinoma arising in this setting appears to be histologically high-grade, it is important to recognize and promptly treat the lesion while still in its in situ phase. Foci with the appearance of CHH may be found in CHC, but in this study progression from CHH to CHC was not observed. A thorough histological examination is needed to distinguish between CHC and CHH. Lesions judged to be CHH are adequately treated by wide excision. Additional long-term, follow-up studies will be necessary to define the precancerous potential of CHH.