Clinicodiagnostic management and bacteriological etiology of non-puerperal mastitis in the population of Southern China

This study aimed to describe the clinicopathologic characteristics of non-puerperal mastitis and to investigate spectrum of organisms causing it in the population of Southern China. We retrospectively registered 364 female patients with histological confirmation of inflammatory disease of the breast in the non-lactational phase, who were admitted to our institution over an 11-year period (2005-2016). Clinical, laboratory, and radiographic imaging features, as well as their bacteriological etiology, were analyzed in detail. In this study, 117 patients were diagnosed with periductal mastitis (PDM)/mammary duct ectasia (MDE) and 247 patients were diagnosed with idiopathic granulomatous mastitis (IGM). There were significant differences in terms of mean age of onset, menstruation period, and menstruation history. Nipple discharge, inverted nipple, and the ratio of abscess and fistula were more spontaneous in women with PDM/MDE compared to IGM. The inflammatory biomarkers including leukocyte count, neutrophil percentage, and high-sensitivity C-reactive protein in PDM/MDE group were significantly higher than IGM group. For bacteriological etiology, the most commonly isolated organism was Corynebacterium kroppenstedtii (C kroppenstedtii) in the IGM group and Staphylococcus in the PDM/MDE group. The study shows that the combination of demographic characteristics and clinicopathological characteristics was helpful in differential diagnosis of PDM/MDE and IGM. IGM can be associated with C kroppenstedtii, providing a possible effective therapeutic and preventive method by targeting this kind of bacilli. Key words: bacteriological etiology; breast disease; idiopathic granulomatous mastitis; mammary ductectasia; periductal mastitis