Magnetic resonance imaging features for differentiating breast papilloma with high-risk or malignant lesions from benign papilloma: a retrospective study on 158 patients

BACKGROUND: Benign breast papilloma is currently managed with conservative management with close observation. In contrast, papilloma with high-risk or malignant lesions warrants surgical excision. The purpose of our study was to investigate magnetic resonance imaging (MRI) features of breast papilloma and to identify imaging diagnostic indicators for papilloma with high-risk or malignant lesions. METHODS: MRI features of 175 surgically confirmed papillomas on 158 patients were retrospectively reviewed. The 175 cases included 132 cases of benign papilloma and 43 cases of papilloma with high-risk or malignant lesions. The MRI features of these lesions were classified into three types: mass, non-mass enhancement (NME), and occult lesion. The occult lesion was defined as the presence of only ductal dilation without any enhanced lesions on MRI. For a mass lesion, the mixed mass-NME lesion was considered if linear, segmental or regional enhanced lesion was found adjacent to the mass. Clinical and MRI features were compared by univariate and multivariate analysis between the benign papilloma and the papilloma with high-risk or malignant lesions. RESULTS: Multivariate logistic regression analysis demonstrated that clinical characteristics including being or older than 50 years (odds ratio [OR] = 4.506), having bloody nipple discharge (OR = 4.499), and concurrent breast cancer (OR = 5.083) were significant indicators for papilloma with high-risk or malignant lesions. On MRI, most papillomas presented as mass (n = 135, 77.1%), and fewer as NME (n = 37, 21.1%) and occult lesion (n = 3, 1.7%). For the mass lesion, the logistic regression analysis demonstrated that a mass size exceeding 10 mm (OR = 2.956) and mixed mass-NME lesion (OR = 4.143) were independent risk indicators for a papilloma with high-risk or malignant lesions. For the NME lesion, the segmental or regional distribution was more commonly observed in the papilloma with high-risk or malignant lesions (61.5%) than the benign papilloma (12.5%) (P = 0.006). All the cases of occult lesions were benign papillomas. CONCLUSIONS: MRI features including a mass size exceeding 10 mm, mixed mass-NME lesion, and NMEs with segmental or regional distribution indicate a papilloma with high-risk or malignant lesions.