Incidental atypical proliferative lesions in reduction mammoplasty specimens: analysis of 2498 cases from 2 tertiary women's health centers.

Atypical proliferative lesions (APLs) are occasionally found in breast reduction specimens. The aim of the study was to investigate the prevalence of APL in reduction mammoplasty specimens from patients who were treated mainly for macromastia. A retrospective medical record review of pathology records on patients who underwent reduction mammoplasty from 2006 to 2012 generated 2498 cases. The sole exclusion criterion was a history of invasive and/or ductal carcinoma in situ (DCIS). Laterality, specimen weight, number of blocks submitted, and presence of APL were recorded and analyzed. We defined APL as invasive carcinoma, DCIS or lobular carcinoma in situ, atypical ductal (ADH) or lobular hyperplasia, and flat epithelial atypia (FEA). The presence of papillomas, radial scars, and fibroadenomas was also recorded. At least 1 APL was identified in 107 (4.3%) of 2498 reduction mammoplasty specimens including invasive duct carcinoma (n = 2), DCIS (n = 4), ADH/FEA (n = 47), and lobular carcinoma in situ/atypical lobular hyperplasia (n = 54). One hundred four (97%) of the 107 patients underwent bilateral, and 3 (3%) underwent unilateral reductions. In conclusion, the frequency of detection of APLs in patients with no history of breast cancer is low (4.3%). Detection of invasive and DCIS lesions is extraordinarily low at 0.2%. The most common APL is lobular neoplasia (2.2%), whereas ADH and FEA are seen in 1.9%. Our findings provide data on the distribution of these lesions in this setting, as well as some insight into their prevalence in the general population. A protocol for submitting tissues from these specimens is also proposed.