The histologic spectrum of apocrine breast proliferations: a comparative study of morphology and DNA content by image analysis.

Apocrine features occurring in sclerosing adenosis (apocrine adenosis), atypical ductal hyperplasia (ADH), and non-comedo ductal carcinoma in situ (DCIS) often add to diagnostic difficulty. We have evaluated the usefulness of DNA content determined by image analysis in apocrine metaplasia and hyperplasia, apocrine adenosis, ADH, DCIS, lobular carcinoma in situ, invasive ductal carcinoma, and infiltrating lobular carcinoma as a potential diagnostic aid in some of these problematic breast lesions with apocrine features. Infiltrating ductal carcinoma and DCIS were further subdivided into high- or low-grade category based on nuclear features. Microscopic fields containing 63 lesions were identified in slides from breast excisions. From each selected area 100 cells in corresponding fields in paired Feulgen-stained sections were digitized for computerized ploidy analysis with lymphocyte nuclei in the same slides serving as internal diploid controls. Aneuploidy was assessed using combined DNA index and modified Auer histogram criteria for DNA content abnormalities. There was strong association between the assessment of nuclear grade and ploidy (Fisher's exact test, P < .00001). All but one of the benign and low-grade malignant lesions (97%) were in the diploid range (six of seven apocrine metaplasia cases, three of three apocrine adenosis cases, 14 of 14 ADH cases, 10 of 10 low-grade DCIS cases, two of two lobular carcinoma in situ cases, and two of two infiltrating lobular carcinoma cases). In contrast, 24 of 25 (96%) of the high-grade malignant lesions were aneuploid (10 of 10 DCIS cases and 14 of 15 infiltrating ductal carcinoma cases). We conclude that DNA ploidy status does not offer additional diagnostic information to light microscopy in distinguishing among benign apocrine proliferations, ADH, and low-grade DCIS since these proliferations share a diploid range DNA content.