ATYPICAL APOCRINE ADENOSIS OF THE BREAST - A CLINICOPATHOLOGICAL STUDY OF 37 PATIENTS WITH 8.7-YEAR FOLLOW-UP

BACKGROUND, Apocrine metaplasia is occasionally superimposed on sclero sing adenosis (apocrine adenosis) in breast biopsies, and cytologic at ypia is sometimes present (atypical apocrine adenosis). The long term risk of patients developing breast carcinoma subsequent to the diagnos is of this lesion is unknown. METHODS. Atypical apocrine adenosis was defined as apocrine adenosis with enlarged nucleoli and a greater than threefold variation in nuclear area. Lesions with recognizable cytoar chitectural patterns of intraductal carcinoma were excluded. Surveilla nce, Epidemiology and End Results (SEER) data were used as the referen ce population for calculations of relative risk. RESULTS, Thirty-seven women with atypical apocrine adenosis had a mean followup of 8.7 pear s. Four patients developed invasive ductal carcinoma of the breast (3 ipsilateral, 1 contralateral) after a mean of 5.6 years. The relative risk of developing carcinoma was 5.5 (95% confidence interval [CI], 1. 9-16). All patients who developed carcinoma were older than age 60 at the time of breast biopsy showing atypical apocrine adenosis, and carc inoma developed at a mean age of 70 years. In the older than 60 years age group (11 patients), the relative risk of developing carcinoma was 14 (95% CI, 4.1-48). CONCLUSIONS, Atypical apocrine adenosis confers an increased risk of developing breast carcinoma in women older than a ge 60, and the risk in younger women is probably low. Some cases of at ypical apocrine adenosis may represent in situ apocrine carcinomas tha t are difficult to diagnose because of the absence of the usual archit ectural features of intraductal carcinoma. (C) 1996 American Cancer So ciety.