OBJECTIVE. The purpose of this article is to characterize the histologic vascular features and distinguishing MR1 features of cystic apocrine metaplasia to better understand im-aging-pathology concordance. MATERIALS AND METHODS. Retrospective review of 261 consecutive MRl-guided biopsy cases was performed. Pathology results were reviewed for all biopsies; cystic apocrine metaplasia was identified as the predominant finding in 19 cases (7%). CD31 immunohisto-chemistry was subsequently performed on the most representative block of cystic apocrine metaplasia, and microvasculature was evaluated using computer-assisted image analysis. The contrast-enhanced MRI examinations correlating with the cystic apocrine metaplasia cases were independently reviewed by two radiologists specializing in breast imaging; lesions were analyzed for morphologic, kinetic, and T2 characteristics. RESULTS. On MRI review, 17 of 19 (89%) lesions were 10 mm or smaller. Washout kinetics were present in 11 of 19 (58%) lesions, and 14 of 19 (74%) lesions were at least partially hyperintense on T2-weighted sequences relative to adjacent glandular tissue. Cystic apocrine metaplasia had a higher percentage area (mean, 4.1%) of CD31-immunostained microvessels compared with background libroglandular tissue (mean, 1.2%). CONCLUSION. Cystic apocrine metaplasia should be considered in the differential diagnosis of a T2-hyperintense enhancing focus or subcenlimeter smoothly marginatcd mass, even if associated with washout kinetics. Cystic apocrine metaplasia contains a statistically significant increase in microvessel area compared with background libroglandular tissue and fat and, therefore, may be considered a concordant result for this set of imaging findings.
- Cystic apocrine metaplasia