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Breast Imaging

E2343. Apocrine Lesions of the Breast: A Multimodality Pictorial Review

Bhatt A,  Anderson T,  Hunt K,  Fazzio R,  Glazebrook K. Mayo Clinic, Rochester , MN

Address correspondence to A. Bhatt (Bhatt.Asha@mayo.edu)

Background Information: Apocrine changes of the breast can present as a broad array of lesions ranging from benign cysts to the rare invasive apocrine carcinoma. The spectrum of apocrine lesions in the breast has been described pathologically; however, imaging features have not been extensively discussed. The purpose of this presentation is to review the various appearances of apocrine lesions using a multimodality approach including mammography, ultrasound and MRI. Knowledge of benign and malignant imaging features of apocrine lesions will aid a radiologist in recommending the appropriate clinical management.

Educational Goals/Teaching Points: 1. Briefly summarize the pathologic characteristics and risk associations of apocrine proliferations in the breast. 2. Discuss the imaging appearances of the variety of apocrine lesions including: Apocrine metaplasia with fibrocystic change, apocrine adenoma, sclerosing adenosis, atypical apocrine hyperplasia, radial scars, papillomas, fibroadenomatoid lesions, DCIS and invasive carcinoma. 3. Emphasis on key features that will help guide the radiologist to the appropriate BI-RADS assessment and clinical management.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques: A. Benign Lesions: 1. Apocrine Metaplasia (AM)- AM is often associated with fibrocystic change. On mammography, these lesions may present as a hypo or iso-dense lobulated mass with or without associated milk of calcium calcifications. Ultrasound demonstrates a cluster of microcysts. MR will demonstrate a T2 hyperintense microlobulated mass with enhancing internal septations and rim enhancement. If imaging findings are classic in appearance, these lesions can be categorized as benign and annual follow up is recommended. 2. Apocrine Adenoma- this is a rare benign adenoma, which is composed of entirely apocrine cells. Imaging shows a well-defined iso-dense mass with a correlative hypoechoic mass on ultrasound. B. Apocrine change present within lesions of undetermined clinical significance: Imaging appearance of such lesions varies and often require stereotactic or ultrasound guided biopsy. 1. Sclerosing Adenosis- Mammographically, this may present as amorphous calcifications. The nodular sclerosis subtype typically presents as a mass with a correlative round or oval mass with or without calcifications on ultrasound. 2. Atypical Apocrine Hyperplasia- Lesions which demonstrate this pathology have variable appearance but will most commonly present as a new isodense asymmetry or mass on mammography with a correlative irregular hypoechoic mass noted on ultrasound. 3. Radial Scars- Radial sclerosing lesions present a spiculated mass or architectural distortion with central lucency. Ultrasound will demonstrate correlative distortion with or without an associated hypoechoic mass. Treatment of such lesions is controversial and depends on additional pathologic findings. 4. Papillomas- Such lesions present as intra-ductal oval or round masses with or without amorphous calcifications. Treatment of these lesions depends of additional pathologic findings. 5. Fibroadenomatoid lesions – These lesions will present as complex solid and cystic masses which appear suspicious on imaging and warrant biopsy. Cystic spaces noted in these lesions mimic the appearance of a phyllodes lesion. C. Apocrine change within malignant lesions: These lesions present with suspicious imaging characteristic which warrant biopsy. As these lesions are malignant, surgical consultation and oncology evaluation should be recommended. 1. DCIS-This will characteristically presents as new or increasing pleomorphic or amorphous calcifications. 2. Invasive carcinoma- Such lesions will classically presents as an irregular spiculated mass with or without pleomorphic calcifications

Conclusion: Apocrine lesions of the breast vary in clinical presentation, imaging appearance and treatment. Knowledge of the spectrum of apocrine lesions in the breast as well as the correlative imaging appearances is important for the interpreting radiologist to allow for appropriate management of patients.