Lesions of Nipple and Axilla

With advances in ultrasound and MRI, breast imagers play an essential role in evaluating nipple pathology. For example, in patients presenting with signs and symptoms of Paget disease of the nipple and a negative mammogram, an MRI is recommended to evaluate the breast for mammographically occult malignancy. A variety of benign and malignant lesions can involve the nipple. Most nipple lesions arise/involve the larger subareolar ducts, for example, mammary duct ectasia, squamous metaplasia of lactiferous ducts (SMOLD), intraductal papilloma, and nipple adenoma. Mammary duct ectasia is the condition where there is ectasia (dilation) of large subareolar ducts. With chronicity, there can be associated periductal inflammation and fibrosis. SMOLD, which can progress to chronic abscesses with fistula formation in the periareolar region, sometimes referred to as Zuska disease, can occur in patients of any age, and both males and females may be affected. Nipple adenoma is a rare benign epithelial lesion that can clinically mimic a malignancy. Syringomatous adenoma of the nipple resembles cutaneous syringoma. This tumor is locally infiltrative and does not cause destructive invasion into the ducts or epidermis. Surgical excision with negative margins is the treatment of choice, as there is a high risk of recurrence (30%) in case of incomplete excisions. The most common malignant lesion of the nipple is Paget disease, which usually presents as a nipple rash. It resembles chronic eczema due to scaling crust, erythema, and exudate. Large breast carcinomas can directly extend into the nipple, and rarely invasive carcinoma can arise in the subareolar tissue. Nipple and subareolar tissue is also a common site for intraductal papilloma, a benign intraductal epithelial proliferation. However, papilloma can have coexistent atypia ranging from ADH to DCIS.